Constraints on the chiral magnetic effect using charge-dependent azimuthal correlations in pPb and PbPb collisions at the LHC
EEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-EP-2017-1932018/04/26
CMS-HIN-17-001
Constraints on the chiral magnetic effect usingcharge-dependent azimuthal correlations in pPb and PbPbcollisions at the LHC
The CMS Collaboration ∗ Abstract
Charge-dependent azimuthal correlations of same- and opposite-sign pairs with re-spect to the second- and third-order event planes have been measured in pPb colli-sions at √ s NN = p T ) difference, and the p T averageof same- and opposite-charge pairs in various event multiplicity ranges. The data sug-gest that the charge-dependent three-particle correlators with respect to the second-and third-order event planes share a common origin, predominantly arising fromcharge-dependent two-particle azimuthal correlations coupled with an anisotropicflow. The CME is expected to lead to a v -independent three-particle correlation whenthe magnetic field is fixed. Using an event shape engineering technique, upper limitson the v -independent fraction of the three-particle correlator are estimated to be 13%for pPb and 7% for PbPb collisions at 95% confidence level. The results of this anal-ysis, both the dominance of two-particle correlations as a source of the three-particleresults and the similarities seen between PbPb and pPb, provide stringent constraintson the origin of charge-dependent three-particle azimuthal correlations and challengetheir interpretation as arising from a chiral magnetic effect in heavy ion collisions. Published in Physical Review C as doi:10.1103/PhysRevC.97.044912. c (cid:13) ∗ See Appendix D for the list of collaboration members a r X i v : . [ nu c l - e x ] A p r It has been suggested that in high-energy nucleus-nucleus (AA) collisions, metastable domainsof gluon fields with nontrivial topological configurations may form [1–4]. These domains cancarry an imbalance between left- and right-handed quarks arising from interactions of chiralquarks with topological gluon fields, leading to a local parity ( P ) violation [3, 4]. This chiralityimbalance, in the presence of the extremely strong magnetic field, which can be produced in anoncentral AA collision, is expected to lead to an electric current perpendicular to the reactionplane, resulting in a final-state charge separation phenomenon known as the chiral magnetic ef-fect (CME) [5–7]. Such macroscopic phenomena arising from quantum anomalies are a subjectof interest for a wide range of physics communities. The chiral-anomaly-induced phenomenahave been observed in magnetized relativistic matter in three-dimensional Dirac and Weyl ma-terials [8–10]. The search for the charge separation from the CME in AA collisions was firstcarried out at RHIC at BNL [11–15] and later at the CERN LHC [16] at various center-of-massenergies. In these measurements, a charge-dependent azimuthal correlation with respect to thereaction plane was observed, which is qualitatively consistent with the expectation of chargeseparation from the CME. No strong collision energy dependence of the signal is observedgoing from RHIC to LHC energies, although some theoretical predictions suggested that thepossible CME signal could be much smaller at the LHC than at RHIC because of a shorter life-time of the magnetic field [17]. Nevertheless, theoretical estimates of the time evolution of themagnetic field have large uncertainties [17].The experimental evidence for the CME in heavy ion collisions remains inconclusive becauseof several identified sources of background correlations that can account for part or all of theobserved charge-dependent azimuthal correlations [18–20]. Moreover, the charge-dependentazimuthal correlation in high-multiplicity pPb collisions has been recently found to have anearly identical value to that observed in PbPb collisions [21]. This is a strong indication thatthe observed effect in heavy ion collisions might predominantly result from background con-tributions. The CME-induced charge separation effect is predicted to be negligible in pPb col-lisions, as the angle between the magnetic field direction and the event plane is expected to berandomly distributed [21, 22].The charge separation can be characterized by the first P -odd sine term ( a ) in a Fourier de-composition of the charged-particle azimuthal distribution [23]:d N d φ ∝ + ∑ n (cid:8) v n cos [ n ( φ − Ψ RP )] + a n sin [ n ( φ − Ψ RP )] (cid:9) , (1)where φ − Ψ RP represents the particle azimuthal angle with respect to the reaction plane angle Ψ RP in heavy ion collisions (determined by the impact parameter and beam axis), and v n and a n denote the coefficients of P -even and P -odd Fourier terms, respectively. Although the reactionplane is not an experimental observable, it can be approximated in heavy ion collisions by thesecond-order event plane, Ψ , determined by the direction of the beam and the maximal par-ticle density in the elliptic azimuthal anisotropy. The P -odd terms will vanish after averagingover events, because the sign of the chirality imbalance changes event by event. Therefore, theobservation of such an effect is only possible through the measurement of particle azimuthalcorrelations. An azimuthal three-particle correlator, γ , proposed to explore the first coeffi-cient, a , of the P -odd Fourier terms characterizing the charge separation [23] is: γ ≡ (cid:10) cos ( φ α + φ β − Ψ ) (cid:11) = (cid:10) cos ( φ α − Ψ ) cos ( φ β − Ψ ) (cid:11) − (cid:10) sin ( φ α − Ψ ) sin ( φ β − Ψ ) (cid:11) .(2) Here, α and β denote particles with the same or opposite electric charge sign and the anglebrackets reflect an averaging over particles and events. Assuming particles α and β are uncor-related, except for their individual correlations with respect to the event plane, the first term onthe right-hand side of Eq. (2) becomes (cid:10) v α v β (cid:11) , which is generally small and independent ofthe charge [12], while the second term is sensitive to the charge separation and can be expressedas (cid:10) a α a β (cid:11) .While the similarity of the pPb and PbPb data at 5.02 TeV analyzed by the CMS experimentpose a considerable challenge to the CME interpretation of the charge-dependent azimuthalcorrelations observed in AA collisions [21], important questions still remain to be addressed: isthe correlation signal observed in pPb collisions entirely a consequence of background corre-lations? What is the underlying mechanism for those background correlations that are almostidentical in pPb and PbPb collisions? Can the background contribution be quantitatively con-strained with data and, if so, is there still evidence for a statistically significant CME signal?In particular, among the proposed mechanisms for background correlations, one source is re-lated to the charge-dependent two-particle correlation from local charge conservation in decaysof resonances or clusters (e.g., jets) [20]. By coupling with the anisotropic particle emission, aneffect resembling charge separation with respect to the reaction plane can be generated. Theobserved characteristic range of the two-particle correlation in data is around one unit of rapid-ity, consistent with short-range cluster decays. In this mechanism of local charge conservationcoupled with the elliptic flow, a background contribution to the three-particle correlator, γ ,is expected to be [24]: γ bkg112 = κ (cid:10) cos ( φ α − φ β ) (cid:11) (cid:10) cos 2 ( φ β − Ψ RP ) (cid:11) = κ δ v . (3)Here, δ ≡ (cid:10) cos ( φ α − φ β ) (cid:11) represents the charge-dependent two-particle azimuthal correlatorand κ is a constant parameter, independent of v , but mainly determined by the kinematicsand acceptance of particle detection [24]. As both the charge conservation effect and anisotropicflow are known to be present in heavy ion collisions, the primary goal of this paper is to conducta systematic investigation of how much of the observed charge-dependent correlations in thedata can be accounted for by this mechanism.Although the background contribution from local charge conservation is well defined in Eq. (3)and has been long recognized [17, 20, 24], it is still not known to what extent background con-tributions account for the observed γ correlator. The main difficulty lies in determining theunknown value of κ in a model-independent way. The other difficulty is to demonstrate di-rectly the linear dependence on v of γ bkg112 , which is nontrivial as one has to ensure the magneticfield, and thus the CME, does not change when selecting events with different v values. There-fore, selecting events with a quantity that directly relates to the magnitude of v is essential.This paper aims to overcome the difficulties mentioned above and achieve a better understand-ing as to the contribution of the local charge conservation background to the charge-dependentazimuthal correlation data. The results should serve as a new baseline for the search for theCME in heavy ion collisions. Two approaches are employed as outlined below.1. Higher-order harmonic three-particle correlator: in heavy ion collisions, the charge sepa-ration effect from the CME is only expected along the direction of the induced magneticfield normal to the reaction plane, approximated by the second-order event plane, Ψ . Asthe symmetry plane of the third-order Fourier term (“triangular flow” [25]), Ψ , is ex-pected to have a weak correlation with Ψ [26], the charge separation effect with respect to Ψ is expected to be negligible. By constructing a charge-dependent correlator withrespect to the third-order event plane, γ ≡ (cid:10) cos ( φ α + φ β − Ψ ) (cid:11) , (4)charge-dependent background effects unrelated to the CME can be explored. In particu-lar, in the context of the local charge conservation mechanism, the γ correlator is alsoexpected to have a background contribution, with γ bkg123 = κ (cid:10) cos ( φ α − φ β ) (cid:11) (cid:10) cos 3 ( φ β − Ψ ) (cid:11) = κ δ v , (5)similar to that for the γ correlator as given in Eq. (3). As the κ and κ parametersmainly depend on particle kinematics and detector acceptance effects, they are expectedto be similar, largely independent of harmonic event plane orders. The relation in Eq. (5)can be generalized for all “higher-order harmonic” three-particle correlators, γ n − n = κ n δ v n . Derivation of Eq. (5) as well as generalization to all higher-order harmonics can befound in Appendix A, which follows similar steps as for that of Eq. (3) given in Ref. [24].One caveat here is that when averaging over a wide η and p T range, the κ n value may alsodepend on the η and p T dependence of the v n harmonic, which is similar, but not exactlyidentical between the v and v coefficients [27, 28].By taking the difference of correlators between same- and opposite-sign pairs (denotedas ∆ γ and ∆ γ among three particles, and ∆ δ between two particles) to eliminate allcharge-independent background sources, the following relation is expected to hold if thecharge dependence of three-particle correlators is dominated by the effect of local chargeconservation coupled with the anisotropic flow: ∆ γ ∆ δ v ≈ ∆ γ ∆ δ v . (6)Therefore, an examination of Eq. (6) will quantify to what extent the proposed back-ground from charge conservation contributes to the γ correlator, and will be a criticaltest of the CME interpretation in heavy ion collisions.2. Event shape engineering (ESE): to establish directly a linear relationship between the γ correlators and v n coefficients, the ESE technique [29] is employed. In a narrow centralityor multiplicity range (so that the magnetic field does not change significantly), events arefurther classified based on the magnitude of the event-by-event Fourier harmonic relatedto the anisotropy measured in the forward rapidity region. Within each event class, the γ correlators and v n values are measured and compared to test the linear relationship. Anonzero intercept value of the γ correlators with a linear fit would reflect the strength ofthe CME.With a higher luminosity pPb run at √ s NN = γ and γ , and the two-particle correlator, δ , are presented in different charge combinationsas functions of the pseudorapidity ( η ) difference ( | ∆ η | ), the transverse momentum ( p T ) dif-ference ( | ∆ p T | ), and the average p T of correlated particles ( p T ). Integrated over η and p T , theevent multiplicity dependence of three- and two-particle correlations is also presented in pPband PbPb collisions. In pPb collisions, the particle correlations are explored separately with respect to the event planes that are obtained using particles with 4.4 < | η | < γ as a function of v inboth pPb and PbPb collisions.This paper is organized as follows. After a brief description of the detector and data samples inSection 2, the event and track selections are discussed in Section 3, followed by the discussionof the analysis technique in Section 4. The results are presented in Section 5, and the paper issummarized in Section 6. The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diam-eter, providing a magnetic field of 3.8 T. Within the solenoid volume, there are four primarysubdetectors, including a silicon pixel and strip tracker detector, a lead tungstate crystal elec-tromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter (HCAL), eachcomposed of a barrel and two endcap sections. The silicon tracker measures charged particleswithin the range | η | < < | η | < η and 0.349 radians in φ . Forcharged particles with 1 < p T <
10 GeV and | η | < p T and 25–90 (45–150) µ m in the transverse (longitudinal) impact parameter [30]. A detaileddescription of the CMS detector, together with a definition of the coordinate system used andthe relevant kinematic variables, can be found in Ref. [31].The pPb data at √ s NN = − . The beam energies are 6.5 TeV for the protons and2.56 TeV per nucleon for the lead nuclei. The data were collected in two different run periods:one with the protons circulating in the clockwise direction in the LHC ring, and one with themcirculating in the counterclockwise direction. By convention, the proton beam rapidity is takento be positive when combining the data from the two run periods. A subset of PbPb dataat √ s NN = γ , data for pPb collisions at √ s NN = 8.16 TeV are compared tothose previously published at √ s NN = 5.02 TeV [21] to examine any possible collision energydependence. Because of statistical limitations, new analyses of higher-order harmonic three-particle correlator and event shape engineering introduced in this paper cannot be performedwith the 5.02 TeV pPb data. The event reconstruction, event selections, and the triggers, including the dedicated triggersto collect a large sample of high-multiplicity pPb events at √ s NN = p T > high-multiplicity pPb collisions, a dedicated trigger was implemented using the CMS level-1(L1) and high-level trigger (HLT) systems. At L1, the total number of towers of ECAL+HCALabove a threshold of 0.5 GeV in transverse energy ( E T ) was required to be greater than a giventhreshold (120 and 150 towers), where a tower is defined by ∆ η × ∆ φ = × | η | < p T > d z / σ ( d z ) and d T / σ ( d T ) ,are required to be less than 3. The relative uncertainty in p T , σ ( p T ) / p T , must be less than 10%.Primary tracks, i.e., tracks that originate at the primary vertex and satisfy the high-purity crite-ria of Ref. [30], are used to define the event charged-particle multiplicity ( N offlinetrk ). To performcorrelation measurements, each track is also required to leave at least one hit in one of the threelayers of the pixel tracker. Only tracks with | η | < p T > N offlinetrk , where primary tracks with | η | < p T > The analysis technique of three-particle correlations employed in this paper is based on that es-tablished in Ref. [21], with the extension of charge-dependent two-particle correlations, higher-order harmonic three-particle correlations, and correlation studies in different event shapeclasses (i.e., ESE analysis). The details are outlined below.
Without directly reconstructing the event plane, the expression given in Eq. (2) can be alter-natively evaluated using a three-particle correlator with respect to a third particle [11, 12], (cid:10) cos ( φ α + φ β − φ c ) (cid:11) / v c , where v c is the elliptic flow anisotropy of particle c with inclu-sive charge sign. The three-particle correlator is measured via the scalar-product method of Q vectors. A complex Q vector for each event is defined as Q n ≡ ∑ Mi = w i e in φ i / W , where φ i is theazimuthal angle of particle i , n is the Fourier harmonic order, M is the number of particles in the Q n calculation in each event, w i is a weight assigned to each particle for efficiency correction,which is derived from a simulation using the HIJING event generator [35]. The W = ∑ Mi = w i represents the weight of the Q vector. In this way, the three-particle correlator can be expressed in terms of the product of Q vectors, i.e., Q α and Q β , when particles α and β are chosen fromdifferent detector phase-space regions or carry different charge signs, γ = (cid:10) cos ( φ α + φ β − φ c ) (cid:11) v c = (cid:68) Q α Q β Q ∗ ± (cid:69)(cid:114) (cid:104) Q ± Q ∗ ∓ (cid:105)(cid:104) Q ± Q ∗ (cid:105)(cid:104) Q ∓ Q ∗ (cid:105) , (7)where the angle brackets on the right-hand side denote an event average of the Q -vector prod-ucts, weighted by the product of their respective total weights W . Here Q is the chargeinclusive Q vector of all particles in the tracker region, and Q ± denotes the Q -vector forparticles c detected in the HF towers. When particles α and β are of the same sign and sharethe same phase space region (denoted as α = β ), an extra term is needed to remove the contri-bution of a particle pairing with itself, so evaluation of the three-particle correlator is modifiedas γ = (cid:10) cos ( φ α + φ β − φ c ) (cid:11) v c = (cid:68) Q Q ∗ ± (cid:69)(cid:114) (cid:104) Q ± Q ∗ ∓ (cid:105)(cid:104) Q ± Q ∗ (cid:105)(cid:104) Q ∓ Q ∗ (cid:105) , (8)where the Q is defined as, Q ≡ (cid:18) ∑ i = w i e i φ i (cid:19) − ∑ i = w i e i φ i (cid:18) ∑ i = w i (cid:19) − ∑ i = w i , (9)and the denominator of Eq. (9) is the respective event weight associated with Q .In the numerators of Eqs. (7) and (8), the particles α and β are identified in the tracker, with | η | < < p T < w i to correct for trackinginefficiency. The particle c is selected by using the tower energies and positions in the HFcalorimeters with 4.4 < | η | < η range for the HF towers imposes an η gapof at least 2 units with respect to particles α and β from the tracker, to minimize possible short-range correlations. To account for any occupancy effect of the HF detectors resulting from thelarge granularities in η and φ , each tower is assigned a weight factor w i corresponding to its E T value when calculating the Q vector. The denominator of the right-hand side of Eqs. (7)and (8) corresponds to the v c using the scalar-product method [11, 12], with Q and Q ± denoting Q vectors obtained from the tracker and the two HF detectors (positive and negative η side) with the same kinematic requirements as for the numerator. The three-particle correlatoris evaluated for particles α and β carrying the same sign (SS) and opposite sign (OS). The SScombinations, ( + , + ) and ( − , − ), give consistent results and are therefore combined. For pPbcollisions, the three-particle correlator is also measured with particle c from HF + and HF − ,corresponding to the p- and Pb-going direction, respectively. For symmetric PbPb collisions,the results from HF + and HF − are consistent with each other and thus combined.The higher-order harmonic three-particle correlator, γ , defined in Eq. (4), is evaluated inexactly the same way as the γ correlator as follows when particles α and β do not overlap, γ = (cid:10) cos ( φ α + φ β − φ c ) (cid:11) v c = (cid:68) Q α Q β Q ∗ ± (cid:69)(cid:114) (cid:104) Q ± Q ∗ ∓ (cid:105)(cid:104) Q ± Q ∗ (cid:105)(cid:104) Q ∓ Q ∗ (cid:105) , (10) .2 Event shape engineering with higher-order Q vectors for particles α and β of SS and OS. Similarly to Eq. (8) when parti-cles α and β can overlap, the γ can be evaluated via γ = (cid:10) cos ( φ α + φ β − φ c ) (cid:11) v c = (cid:68) Q Q ∗ ± (cid:69)(cid:114) (cid:104) Q ± Q ∗ ∓ (cid:105)(cid:104) Q ± Q ∗ (cid:105)(cid:104) Q ∓ Q ∗ (cid:105) , (11)where Q is defined as Q ≡ (cid:18) ∑ i = w i e i φ i ∑ i = w i e i φ i (cid:19) − ∑ i = w i e i φ i (cid:18) ∑ i = w i (cid:19) − ∑ i = w i , (12)and the respective event weight associated with Q is the denominator of Eq. (12).Similarly, the charge-dependent two-particle correlator, δ ≡ (cid:10) cos ( φ α − φ β ) (cid:11) , is also evaluatedwith Q vectors as δ = (cid:68) Q α Q ∗ β (cid:69) when particles α and β are chosen from different detectorphase-space regions or have opposite signs, or otherwise, δ = (cid:42) (cid:18) ∑ i = w i e i φ i ∑ i = w i e − i φ i (cid:19) − ∑ i = w i (cid:18) ∑ i = w i (cid:19) − ∑ i = w i (cid:43) , (13)and the respective event weight is the denominator of Eq. (13).The effect of the nonuniform detector acceptance is corrected by evaluating the cumulants of Q -vector products [36]. While the correction is found to be negligible for the γ and δ correlators,there is a sizable effect of 5–10% correction to the γ correlator. In the ESE analysis, within each multiplicity range of pPb or centrality range of PbPb data,events are divided into different q classes, where q is defined as the magnitude of the Q vector. In this analysis, the q value is calculated from one side of the HF region within therange 3 < η < E T ), where in pPbcollisions only the Pb-going side of HF is used because of the poor resolution from a relativelylow charged-particle multiplicity on the proton-going side. In each q class, the v harmonic ismeasured with the scalar product method using a common resolution term ( v c ) as in the γ correlator. Therefore, the v from the tracker region can be expressed in terms of the Q-vectorsas v = (cid:68) Q α Q ∗ ± (cid:69)(cid:114) (cid:104) Q ± Q ∗ ∓ (cid:105)(cid:104) Q ± Q ∗ (cid:105)(cid:104) Q ∓ Q ∗ (cid:105) , (14)where particles from the HF are selected from the same region as particle c in the γ correlator.In PbPb collisions, the particle c in the γ correlator is taken from the HF detector that is at theopposite η side to the one used to calculate q . However, the results are in good agreement withthose where the particle c for γ and q is measured from the same side of the HF detector, < 5.0) h (3.0 < q N u m be r o f e v en t s - ESE classes: q11
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CMS pPb 8.16 TeV < 250 trkoffline N £ Figure 1: The q classes are shown in different fractions with respect to the total number ofevents in multiplicity range 185 ≤ N offlinetrk <
250 in PbPb (left) and pPb (right) collisions at √ s NN = c in the γ correlator withrespect to the Pb- and p-going sides is studied, when q is measured only in the Pb-going side.The results are found to be independent of the side in which the particle c is detected.In Fig. 1, the HF q distributions are shown for PbPb and pPb collisions in the multiplicityrange 185 ≤ N offlinetrk < q class. For each q class, the three-particle γ is calculated with the default kinematic regions for particles α , β , and c , and the v harmonicsfrom the tracker ( | η | < v values for tracker particles as a function of the average q in each HF q classare shown. A proportionality close to linear is seen, indicating the two quantities are stronglycorrelated because of the initial-state geometry [38]. The absolute systematic uncertainties of the two-particle correlator δ , and three-particle cor-relators γ and γ , have been studied. Varying the d z / σ ( d z ) and d T / σ ( d T ) from less than3 (default) to less than 2 and 5, and the σ ( p T ) / p T <
10% (default) to σ ( p T ) / p T < ± × − for the γ , ± × − for the γ ,and ± × − for the δ correlator. The longitudinal primary vertex position ( V z ) has beenvaried, using ranges | V z | < < | V z | <
15 cm, where the differences with respectto the default range | V z | <
15 cm are ± × − for the γ , ± × − for the γ , and ± × − for the δ correlator, taken as the systematic uncertainty. In the pPb collisions only,using the lower-threshold of the high-multiplicity trigger with respect to the default trigger,yields a systematic uncertainty of ± × − for all three correlators, which accounts for thepossible trigger bias from the inefficiency of the default trigger around the threshold. In the .3 Systematic uncertainties < 5.0) h (3.0 < q | < . ) h ( | v CMS < 250 trkoffline N £ PbPb 5.02 TeVpPb 8.16 TeV
Figure 2: The correlation between the tracker v and the HF q is shown for pPb and PbPbcollisions at collisions at √ s NN = γ and δ have been found to be ± × − , and for γ is to be ± × − .A final test of the analysis procedures is done by comparing “known” charge-dependent sig-nals based on the EPOS event generator [39] to those found after events are passed through aG
EANT ± × − is assigned for the γ , ± × − for the γ , and ± × − forthe δ correlators, by taking the difference in the correlators between the reconstructed and thegenerated level. Note that this uncertainty for the δ correlator is based on differential variables,where the uncertainty covers the maximum deviation from the closure test. For results thataveraged over | ∆ η | < ± × − when directlyevaluating the average. The tracking efficiency and acceptance of positively and negativelycharged particles have been evaluated separately, and the difference has been found to be negli-gible. All sources of systematic uncertainty are uncorrelated and added in quadrature to obtainthe total absolute systematic uncertainty. No dependence of the systematic uncertainties on thesign combination, multiplicity, ∆ η , ∆ p T , or average- p T is found. The systematic uncertaintiesin our results are point-to-point correlated. In pPb collisions, the systematic uncertainty is alsoobserved to be independent of particle c pointing to the Pb- or p-going direction, and thus it isquoted to be the same for these two situations. The systematic uncertainties are summarizedin Table 1. Table 1: Summary of systematic uncertainties in SS and OS three-particle correlators γ and γ , and two-particle correlator δ in pPb collisions at √ s NN = γ ( × − ) γ ( × − ) δ ( × − )Track selections 1.0 4.0 1.0Vertex Z position 1.0 3.0 1.0Pileup (pPb only) 1.0 3.0 0.1High multiplicity trigger bias (pPb only) 3.0 3.0 0.3MC closure 2.5 4.0 5.0Total in pPb 4.3 7.7 5.2Total in PbPb 2.9 6.4 5.2 Measurements of the charge-dependent three-particle ( γ , γ ) and two-particle ( δ ) correla-tors are shown in Fig. 3 as functions of the pseudorapidity difference ( | ∆ η | ≡ | η α − η β | ) betweenSS and OS particles α and β , in the multiplicity range 185 ≤ N offlinetrk <
250 for pPb collisionsat √ s NN = δ correlators are shownwith different markers to differentiate the two-particle correlation from the three-particle cor-relation with a particle c in the forward rapidity. The pPb data are obtained with particle c inthe Pb- and p-going sides separately. The multiplicity range 185 ≤ N offlinetrk <
250 for PbPb dataroughly corresponds to the centrality range 60–65%.Similar to the observation reported in Ref. [21], the three-particle γ (Figs. 3a and 3b) and γ (Figs. 3c and 3d) correlators show a charge dependence for | ∆ η | up to about 1.6, in both pPb(5.02 [21] and 8.16 TeV) and PbPb (5.02 TeV) systems. Little collision energy dependence of the γ data for pPb collisions is found from √ s NN = | ∆ η | > | ∆ η | out toabout 4.8 units. In pPb collisions, the γ correlator obtained with particle c from the p-goingside is shifted toward more positive values than that from the Pb-going side by approximatelythe same amount for both the SS and OS pairs. This trend is reversed for the higher-orderharmonic γ correlator, where the Pb-going side data are more positive than the p-goingside data. The Pb-going side results for the γ correlator for the pPb collisions are of similarmagnitude as the results for PbPb collisions, although a more pronounced peak structure atsmall | ∆ η | is observed in pPb collisions. The common shift of SS and OS correlators betweenthe p- and Pb-going side reference ( c ) particle may be related to sources of correlation that arecharge independent, such as directed flow (the first-order azimuthal anisotropy in Eq. (1)) andthe momentum conservation effect, the latter being sensitive to the difference in multiplicitybetween p- and Pb-going directions. The two-particle δ correlators (Figs. 3e and 3f) for both SSand OS pairs also show a decreasing trend as | ∆ η | increases and converge to the same valuesat | ∆ η | ≈ δ correlators are found to be larger in pPb than in PbPb collisions at similar multiplicities. Asthe δ correlator is sensitive to short-range jet-like correlations, reflected by the low- | ∆ η | region,this effect may be related to the higher- p T jets or clusters in pPb compared to PbPb collisionsat similar multiplicities, as suggested in Ref. [28], because of short-range two-particle ∆ η – ∆ φ correlations.To provide more detailed information on the particle p T dependence of the correlations, the .1 Charge-dependent two- and three-particle correlators | hD | g - - · pPb 8.16 TeV < 250 trkoffline N £
185 (a) | hD | g - - · PbPb 5.02 TeV
CMS < 250 trkoffline N £
185 (b) | hD | g - - - · (c) (Pb-going) c f (p-going) c f SS OS | hD | g - - - · (d) | hD | d - · (e) SS OS | hD | d - · (f) Figure 3: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ η | for 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = c in Pb-going (solid markers) and p-going (open markers) sides are shown separately.The SS and OS two-particle correlators are denoted by different markers for both pPb and PbPbcollisions. Statistical and systematic uncertainties are indicated by the error bars and shadedregions, respectively. γ , γ , and δ correlators are measured as functions of the p T difference ( | ∆ p T | ≡ | p T, α − p T, β | )and average ( p T ≡ ( p T, α + p T, β ) /2) of the SS and OS pairs in pPb and PbPb collisions, andshown in Figs. 4 and 5. The | ∆ p T | - and p T -dependent results are averaged over the full | η | < p T region [6].For all correlators, similar behaviors between pPb and PbPb data are again observed. Thetrends in | ∆ p T | for γ and γ correlators seem to be opposite. The γ correlator increasesas a function of | ∆ p T | , while a decreasing trend is seen for the γ correlator up to | ∆ p T | ≈ γ becomes constant in | ∆ p T | . The opposite behavior observed between the γ and γ correlators is related to back-to-back jet-like correlations, which give a positive(negative) contribution to even- (odd-) order Fourier harmonics [42]. The δ correlators decreasemonotonically as functions of | ∆ p T | for both SS and OS pairs in pPb and PbPb collisions. Thistrend of decreasing for δ is consistent with the expectation from either transverse momentumconservation or back-to-back jet correlations [19].In terms of the p T dependence in Fig. 5, all three correlators for both SS and OS pairs showvery similar behaviors in the low- p T region, which is likely a consequence of the same physical | (GeV) T p D | g - · pPb 8.16 TeV < 250 trkoffline N £
185 (a) | (GeV) T p D | g - · PbPb 5.02 TeV
CMS < 250 trkoffline N £
185 (b) | (GeV) T p D | g - - - - · (c) (Pb-going) c f (p-going) c f SS OS | (GeV) T p D | g - - - - · (d) | (GeV) T p D | d - - · (e) SS OS | (GeV) T p D | d - - · (f) Figure 4: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ p T | for 185 ≤ N offlinetrk <
250 in pPb collisionsat √ s NN = c in Pb-going (solid markers) and p-going (open markers) sides are shownseparately. The SS and OS two-particle correlators are denoted by different markers for bothpPb and PbPb collisions. Statistical and systematic uncertainties are indicated by the error barsand shaded regions, respectively.origin. However, an opposite trend starts emerging at p T ≈ γ and δ . Within the 0.3 < p T < p T increases toward 3 GeV, both particles of apair tend to be selected with a high- p T value, while for low- p T or any | ∆ p T | values, the pairusually consists of at least one low- p T particle. This may be the reason for a different trendseen at high p T . The qualitative behavior of the data is captured by the A Multi-Phase Transportmodel [43, 44]. In Appendix C, all three correlators as functions of | ∆ η | , ∆ p T , and p T in differentmultiplicity and centrality ranges in pPb and PbPb collisions, can be found.To explore the multiplicity or centrality dependence of the three- and two-particle correlators,an average of the data is taken over | ∆ η | < | ∆ η | < | ∆ η | , and all further plots averaged over | ∆ η | < | ∆ η | -averaged data of γ , γ and δ are shown in Fig. 6 for both OS and SS pairs, asfunctions of N offlinetrk for pPb collisions at √ s NN = c from the Pb-going side) andPbPb collisions at 5.02 TeV. Previously published pPb data at 5.02 TeV are also shown for com-parison [21]. The centrality scale on the top of Fig. 6 relates to the PbPb experimental results.Up to N offlinetrk = N offlinetrk ranges. The .1 Charge-dependent two- and three-particle correlators (GeV) T p g - - · pPb 8.16 TeV < 250 trkoffline N £
185 (a) (GeV) T p g - - · PbPb 5.02 TeV
CMS < 250 trkoffline N £
185 (b) (GeV) T p g - - · (c) (Pb-going) c f (p-going) c f SS OS (GeV) T p g - - · (d) (GeV) T p d - · (e) SS OS (GeV) T p d - · (f) Figure 5: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of p T for 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = c in Pb-going (solid markers) and p-going (open markers) sides are shown separately.The SS and OS two-particle correlators are denoted by different markers for both pPb and PbPbcollisions. Statistical and systematic uncertainties are indicated by the error bars and shadedregions, respectively.new pPb data at 8.16 TeV extend the multiplicity reach further than the previously publishedpPb data at 5.02 TeV (which stopped at N offlinetrk ≈ γ correlators in pPb and PbPb collisions exhibit thesame magnitude and trend as functions of event multiplicity. The pPb data are independentof collision energy from 5.02 to 8.16 TeV at similar multiplicities. This justifies the comparisonof new pPb data and PbPb data at somewhat different energies. For both pPb and PbPb colli-sions, the OS correlator reaches a value close to zero for N offlinetrk > N offlinetrk increases. Part of the ob-served multiplicity (or centrality) dependence is understood as a dilution effect that falls withthe inverse of event multiplicity [12]. The notably similar magnitude and multiplicity depen-dence of the three-particle correlator, γ , observed in pPb collisions relative to that in PbPbcollisions again indicates that the dominant contribution of the signal is not related to the CME.The results of SS and OS three-particle correlators as functions of centrality in PbPb collisionsat √ s NN = γ correlators between pPb and PbPb are observed to bedifferent, unlike those for γ correlators. As the CME contribution to γ is not expected, the trkoffline N d - · pPb 8.16 TeV SS OS trkoffline N g - - · (Pb-going) c f pPb 8.16 TeV, PbPb 5.02 TeV SS OS trkoffline N g - - · (CMS 2017)SS OS | < 1.6 hD | (Pb-going) c f pPb 5.02 TeV, PbPb centrality(%)55 45 3565
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Figure 6: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), averaged over | ∆ η | < N offlinetrk in pPb collisionsat √ s NN = γ for pPb collisions at5.02 TeV from CMS Collaboration (CMS 2017: [21]), are also shown for comparison. Statisticaland systematic uncertainties are indicated by the error bars and shaded regions, respectively. .1 Charge-dependent two- and three-particle correlators | hD | gD - · < 250 trkoffline N £ | (GeV) T p D | gD - · (Pb-going) c f pPb 8.16 TeV, (p-going) c f pPb 8.16 TeV, PbPb 5.02 TeV (GeV) T p gD - · CMS | hD | gD - · | T p D | gD - · T p gD - · | hD | dD - · | (GeV) T p D | dD - · pPb 8.16 TeV PbPb 5.02 TeV (GeV) T p dD - · Figure 7: The difference of the OS and SS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower) as functions of ∆ η (left), ∆ p T (middle), and p T (right) for 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = ∆ δ correlator is denoted by a different marker for pPb collisions. The pPb resultsare obtained with particle c from Pb- and p-going sides separately. Statistical and systematicuncertainties are indicated by the error bars and shaded regions, respectively.data suggest different properties of backgrounds in pPb and PbPb systems. If the γ correla-tor in pPb data is expected to be background dominated, as argued earlier, the similarity foundto the PbPb data in γ requires further understanding. The two-particle δ correlators show asimilar trend in multiplicity between pPb and PbPb systems, but a larger splitting between OSand SS pairs is observed in pPb than in PbPb data.To eliminate sources of correlations that are charge independent (e.g., directed flow, v ) and toexplore a possible charge separation effect generated by the CME or charge-dependent back-ground correlations, the differences of three-particle correlators, ∆ γ and ∆ γ , and two-particle correlator, ∆ δ , between OS and SS are shown in Fig. 7 as functions of | ∆ η | , | ∆ p T | , and p T in the multiplicity range 185 ≤ N offlinetrk <
250 for pPb collisions at √ s NN = ∆ γ and ∆ γ , in pPb collisionswith particle c from either the p- or Pb-going side, and in PbPb collisions, show nearly iden-tical values, except in the high p T region. Note that for OS and SS correlators separately, thissimilarity between pPb and PbPb is only observed for the γ correlator. As a function of | ∆ η | ,the charge-dependent difference is largest at | ∆ η | ≈ | ∆ η | > | ∆ η | , | ∆ p T | and p T strongly suggests a common physical trkoffline N dD - · pPb 8.16 TeVPbPb 5.02 TeV trkoffline N gD - · (Pb-going) c f pPb 8.16 TeV, (p-going) c f pPb 8.16 TeV, PbPb 5.02 TeV trkoffline N gD - · (Pb-going) c f pPb 5.02 TeV, (p-going) c f pPb 5.02 TeV, CMS 2017:
CMS | < 1.6 hD | PbPb centrality(%)55 45 3565
Figure 8: The difference of the OS and SS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), averaged over | ∆ η | < N offlinetrk in pPb collisions at √ s NN = c from Pb- and p-going sides separately. The ∆ δ correlator is denotedby a different marker for pPb collisions. The results of γ for pPb collisions at 5.02 TeV fromCMS Collaboration (CMS 2017: [21]), are also shown for comparison. Statistical and systematicuncertainties are indicated by the error bars and shaded regions, respectively. .1 Charge-dependent two- and three-particle correlators origin. As argued in Ref. [21], a strong charge separation signal from the CME is not expectedin a very high-multiplicity pPb collisions, and not with respect to Ψ (for the γ correlator) ineither the pPb or PbPb system. The similarity seen between high-multiplicity pPb and periph-eral PbPb collisions for both ∆ γ and ∆ γ further challenges the attribution of the observedcharge-dependent correlations to the CME. The two-particle correlator, ∆ δ , on the other hand,is found to show a larger value in pPb than in PbPb collisions. trkoffline N dD n / v , n - ; n gD (Pb-going) c f n = 2, (Pb-going) c f n = 3, CMS | < 1.6 hD |pPb 8.16 TeV PbPb centrality(%)55 45 3565 trkoffline N dD n / v , n - ; n gD n = 2n = 3 PbPb 5.02 TeV| < 1.6 hD | Figure 9: The ratio of ∆ γ and ∆ γ to the product of v n and δ , averaged over | ∆ η | < √ s NN = ∆ γ and ∆ γ , and two-particle correlator, ∆ δ ,between OS and SS are shown in Fig. 8 as functions of N offlinetrk averaged over | ∆ η | < √ s NN = ∆ γ and ∆ γ is strikingly similar in pPb and PbPbcollisions over the entire overlapping multiplicity range (and also independent of collision en-ergy for ∆ γ in pPb), while higher values of an OS-SS difference in ∆ δ are found for the pPbsystem.8
Figure 8: The difference of the OS and SS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), averaged over | ∆ η | < N offlinetrk in pPb collisions at √ s NN = c from Pb- and p-going sides separately. The ∆ δ correlator is denotedby a different marker for pPb collisions. The results of γ for pPb collisions at 5.02 TeV fromCMS Collaboration (CMS 2017: [21]), are also shown for comparison. Statistical and systematicuncertainties are indicated by the error bars and shaded regions, respectively. .1 Charge-dependent two- and three-particle correlators origin. As argued in Ref. [21], a strong charge separation signal from the CME is not expectedin a very high-multiplicity pPb collisions, and not with respect to Ψ (for the γ correlator) ineither the pPb or PbPb system. The similarity seen between high-multiplicity pPb and periph-eral PbPb collisions for both ∆ γ and ∆ γ further challenges the attribution of the observedcharge-dependent correlations to the CME. The two-particle correlator, ∆ δ , on the other hand,is found to show a larger value in pPb than in PbPb collisions. trkoffline N dD n / v , n - ; n gD (Pb-going) c f n = 2, (Pb-going) c f n = 3, CMS | < 1.6 hD |pPb 8.16 TeV PbPb centrality(%)55 45 3565 trkoffline N dD n / v , n - ; n gD n = 2n = 3 PbPb 5.02 TeV| < 1.6 hD | Figure 9: The ratio of ∆ γ and ∆ γ to the product of v n and δ , averaged over | ∆ η | < √ s NN = ∆ γ and ∆ γ , and two-particle correlator, ∆ δ ,between OS and SS are shown in Fig. 8 as functions of N offlinetrk averaged over | ∆ η | < √ s NN = ∆ γ and ∆ γ is strikingly similar in pPb and PbPbcollisions over the entire overlapping multiplicity range (and also independent of collision en-ergy for ∆ γ in pPb), while higher values of an OS-SS difference in ∆ δ are found for the pPbsystem.8 | hD |0 1 2 dD n / v , n - ; n gD pPb 8.16 TeV < 250 trkoffline N £ | (GeV) T p D |0 1 2 dD n / v n gD (Pb-going) c f n = 2, (p-going) c f n = 2, (Pb-going) c f n = 3, (GeV) T p0 1 2 dD n / v n gD CMS | hD |0 1 2 dD n / v , n - ; n gD PbPb 5.02 TeV < 250 trkoffline N £ | (GeV) T p D |0 1 2 dD n / v n gD n = 2n = 3 (GeV) T p0 1 2 dD n / v n gD Figure 10: The ratio of ∆ γ and ∆ γ to the product of v n and δ , as functions of ∆ η (left), ∆ p T (middle), and p T (right) for 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = ∆ γ and ∆ γ correlators, the relation in Eq. (6)is used. The ratios of ∆ γ and ∆ γ to the product of ∆ δ and v n are shown in Fig. 9, averagedover | ∆ η | < v and v values for particles α or β are calculated with the scalar-product method with respect to the par-ticle c . In pPb collisions, only results with the Pb-going direction are shown because the p-goingdirection data lack statistical precision, except for the multiplicity range 185 ≤ N offlinetrk < n =2 and n =3, onaverage with values slightly less than 2. This observation indicates that the measured chargedependence of three-particle correlators is consistent with mostly being dominated by charge-dependent two-particle correlations (e.g., from local charge conservation) coupled with theanisotropic flow v n . For a given n value, the ratios are also similar between pPb and PbPbcollisions (and may reflect similar particle kinematics and acceptances), and approximatelyconstant as functions of event multiplicity. Notably, the ∆ δ in Fig. 8 are different betweenthe pPb and PbPb systems. However, the anisotropic flow harmonics v n are larger for PbPbcollisions than for pPb collisions [28]. As a result, the product of ∆ δ and v n leads to similarvalues of ∆ γ and ∆ γ correlators between the pPb and PbPb systems, implying the κ issimilar to κ .The ratios of ∆ γ and ∆ γ to the product of ∆ δ and v n can also be studied as functions of | ∆ η | , ∆ p T , and p T in pPb and PbPb collisions, as shown in Fig. 10 for the multiplicity rangeof 185 ≤ N offlinetrk < v n are calculated as the average v n of particles α and β , v n = ( v n , α + v n , β ) /2 (based on the relation derived in Eq. (21) in Appendix A), and are weightedby the number of pairs of particles α and β in the given kinematic ranges when averaged over η or p T . The ratios involving ∆ γ and ∆ γ are again found to be similar differentially for all .2 Event shape engineering three variables in both pPb and PbPb collisions. This observation further supports a commonorigin of ∆ γ and ∆ γ from charge-dependent two-particle correlations coupled with theanisotropic flow. To explore directly the background scenario in Eq. (3) in terms of a linear dependence on v forthe γ correlator, results based on the ESE analysis are presented in this section. | < 2.4) h (| v g - - · CMS (Pb-going) c f (p-going) c f SS OS pPb 8.16 TeV < 250 trkoffline N £
185 | < 1.6 hD | | < 2.4) h (| v g - - · PbPb 5.02 TeV < 250 trkoffline N £
185 | < 1.6 hD | Figure 11: The SS and OS three-particle correlators, γ , averaged over | ∆ η | < v (evaluated as the average v value for each corresponding q event class), for themultiplicity range 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = c from Pb- and p-goingsides separately. Statistical and systematic uncertainties are indicated by the error bars andshaded regions, respectively.The SS and OS three-particle correlators, γ , averaged over | ∆ η | < v (evaluated as the average v value for each corresponding q event class in Fig. 11),for the multiplicity range 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = c from the Pb-and p-going sides separately. | < 2.4) h (| v gD - · | < 1.6 hD | CMS < 250 trkoffline N £ (Pb-going) c f pPb 8.16 TeV, (p-going) c f pPb 8.16 TeV, PbPb 5.02 TeV | < 2.4) h (| v gD - · | < 1.6 hD | CMS
PbPb 5.02 TeV
Cent. 60-70%Cent. 50-60%Cent. 45-50%Cent. 40-45%Cent. 35-40%Cent. 30-35%
Figure 12: The difference of the OS and SS three-particle correlators, γ , averaged over | ∆ η | < v evaluated in each q class, for the multiplicity range 185 ≤ N offlinetrk < √ s NN = .2 Event shape engineering Both SS and OS γ correlators in both pPb (both beam directions for particle c ) and PbPbcollisions show a dependence on v . A clear linear dependence on the v value is not seen forany of the SS and OS correlators studied.Similar to the analysis in Section 5.1, the difference between OS and SS correlators is takenin order to eliminate the charge-independent sources of the correlators. The results, averagedover | ∆ η | < v evaluated in each q class,for the multiplicity range 185 ≤ N offlinetrk <
250 in pPb collisions at √ s NN = ∆ γ = a v + b , (15)where the first term corresponds to the v -dependent background contribution with the slopeparameter a equal to κ ∆ δ (from Eq. (3)), which is assumed to be v independent. The interceptparameter b denotes the v -independent contribution (when linearly extrapolating to v =
0) inthe γ correlator. In particular, as the CME contribution to the ∆ γ is expected to be largely v -independent within narrow multiplicity (centrality) ranges, the b parameter may provide anindication to a possible observation of the CME, or set an upper limit on the CME contribution.As shown in Fig. 12, for both pPb and PbPb collisions in each multiplicity or centrality range, aclear linear dependence of the ∆ γ correlator as a function of v is observed. Fitted by a linearfunction, the intercept parameter, b , can be extracted. A one standard deviation uncertaintyband is also shown for the linear fit. Taking the statistical uncertainties into account, the valuesof b are found to be nonzero for multiplicity range 185 ≤ N offlinetrk <
250 in pPb and 60–70%centrality in PbPb collisions.Observing a nonzero intercept b from Fig. 12 may or may not lead to a conclusion of a finiteCME signal, as an assumption is made for the background contribution term, namely that ∆ δ isindependent of v . To check this assumption explicitly, the ∆ δ correlator is shown in Fig. 13 asa function of v in different multiplicity and centrality ranges in pPb (upper) and PbPb (lower)collisions. It is observed that the value of ∆ δ remains largely constant as a function of v inlow- or intermediate- q classes, but starts rising as v increases in high- q classes. The multi-plicity, within a centrality or multiplicity range, decreases slightly with increasing q , whichqualitatively could contribute to the rising ∆ δ due to a multiplicity dilution effect. However,this is only found to be true for PbPb collisions, but not for pPb collisions. The other reasonmay be related to larger jet-like correlations selected by requiring large q values. Events withhigher multiplicities show a weaker dependence on v than those with lower multiplicities,which is consistent with the expectation that short-range jet-like correlations are stronger inperipheral events. Because of the possible bias towards larger jet-like correlations at higher q from the ESE technique, the v dependence of ∆ δ is hard to completely eliminate. This presentsa challenge to the interpretation of the intercept values from the linear fits in Fig. 12.In order to avoid the issue of ∆ δ being dependent on v , the ratio ∆ γ / ∆ δ as function of v isshown in Fig. 14 for different multiplicity ranges in pPb collisions at √ s NN = v -dependent background, the ratio ∆ γ / ∆ δ is expected to be proportionalto v . A linear function is fitted again using ∆ γ ∆ δ = a norm v + b norm . (16)Here, comparing to the intercept parameter b in Eq. (15), the b norm parameter is equivalent to b scaled by the ∆ δ factor. The fitted linear slope and intercept parameters, a norm and b norm , are | < 2.4) h (| v dD - · CMS | < 1.6 hD |pPb 8.16 TeV < 150 trkoffline N £
120 < 185 trkoffline N £
150 < 250 trkoffline N £
185 < 300 trkoffline N £
250 < 400 trkoffline N £ | < 2.4) h (| v dD - · CMS
PbPb 5.02 TeV
Cent. 60-70%Cent. 50-60%Cent. 45-50%Cent. 40-45%Cent. 35-40%Cent. 30-35% | < 1.6 hD | Figure 13: The difference of the OS and SS two-particle correlators, δ , averaged over | ∆ η | < v evaluated in each q class, for different multiplicity ranges in pPb collisionsat √ s NN = .2 Event shape engineering | < 2.4) h (| v dD / gD < 150 trkoffline N £ pPb 8.16 TeV(Pb-going) c f | < 1.6 hD | | < 2.4) h (| v dD / gD < 185 trkoffline N £ CMS | < 2.4) h (| v dD / gD < 250 trkoffline N £ | < 2.4) h (| v dD / gD < 300 trkoffline N £ | < 2.4) h (| v dD / gD Cent. 30-35%PbPb 5.02 TeV| < 1.6 hD | | < 2.4) h (| v dD / gD Cent. 35-40%
CMS | < 2.4) h (| v dD / gD Cent. 40-45% | < 2.4) h (| v dD / gD Cent. 45-50% | < 2.4) h (| v dD / gD Cent. 50-60% | < 2.4) h (| v dD / gD Cent. 60-70%
Figure 14: The ratio between the difference of the OS and SS three-particle correlators and thedifference of OS and SS in δ correlators, ∆ γ / ∆ δ , averaged over | ∆ η | < v evaluated in each q class, for different multiplicity ranges in pPb collisions at √ s NN = Table 2: The summary of slope and intercept parameter a norm and b norm for different N offlinetrk classes in pPb collisions, and the goodness of fit χ per degree of freedom (ndf). The statisticaland systematic uncertainties are shown after the central values, respectively. N offlinetrk a norm b norm χ /ndf120–150 1.13 ± ± ± ± ± ± ± ± ± ± − ± ± ± ± − ± ± a norm and b norm for different centralityclasses in PbPb collisions, and the goodness of fit χ per degree of freedom (ndf). The statisticaland systematic uncertainties are shown after the central values, respectively.Centrality a norm b norm χ /ndf60–70% 1.85 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± − ± ± ± ± − ± ± N offlinetrk and centrality classes for pPb and PbPb collisions,respectively.The values of the intercept parameter b norm are shown as a function of event multiplicity inFig. 15 (upper) , for both pPb and PbPb collisions. The ± σ and ± σ systematic uncertainty isshown, which correspond to a 68% and 95% confidence level (CL), respectively. Within statis-tical and systematic uncertainties, no significant positive value for b norm is observed for mostmultiplicities in pPb or centralities in PbPb collisions. For multiplicity ranges 120 ≤ N offlinetrk <
150 and 150 ≤ N offlinetrk <
185 in pPb collisions, an indication of positive values with signif-icances of more than two standard deviations is seen. However, results in these multiplicityranges are likely to be highly sensitive to the very limited v coverage using the ESE technique,as shown in the upper panel of Fig. 14. Overall, the result suggests that the v -independentcontribution to the ∆ γ correlator is consistent with zero, and correlation data are consis-tent with the background-only scenario of charge-dependent two-particle correlations plus ananisotropic flow, v n . This conclusion is consistent with that drawn from the study of higher-order harmonic three-particle correlators discussed earlier.Based on the assumption of a nonnegative CME signal, the upper limit of the v -independentfraction in the ∆ γ correlator is obtained from the Feldman–Cousins approach [45] with themeasured statistical and systematic uncertainties. In Fig. 15 (lower), the upper limit of thefraction f norm , where f norm is the ratio of the b norm value to the value of (cid:104) ∆ γ (cid:105) / (cid:104) ∆ δ (cid:105) , is pre-sented at 95% CL as a function of event multiplicity. The v -independent component of the ∆ γ correlator is less than 8–15% for most of the multiplicity or centrality range. The com-bined limits from all presented multiplicities and centralities are also shown in pPb and PbPbcollisions. An upper limit on the v -independent fraction of the three-particle correlator, orpossibly the CME signal contribution, is estimated to be 13% in pPb and 7% in PbPb collisions,at 95% CL. Note that the conclusion here is based on the assumption of a CME signal inde-pendent of v in a narrow multiplicity or centrality range. As pointed out in a study by theALICE collaboration after this manuscript was submitted [46], the observed CME signal may be reduced as v decreases for small v values (e.g., < v values in this analysis (6–15%), the v dependence of the observedCME signal is minimized to the largest extent, especially for more central events. The data alsorule out any significant nonlinear v dependence of the observed CME signal, as suggested byRef. [46]. Therefore, the high-precision data presented in this paper indicate that the charge-dependent three-particle azimuthal correlations in pPb and PbPb collisions are consistent witha v -dependent background-only scenario, posing a significant challenge to the search for theCME in heavy ion collisions using three-particle azimuthal correlations. Charge-dependent azimuthal correlations of same- and opposite-sign (SS and OS) pairs withrespect to the second- and third-order event planes have been studied in pPb collisions at √ s NN = 8.16 TeV and PbPb collisions at 5.02 TeV by the CMS experiment at the LHC. The cor-relations are extracted via three-particle correlators as functions of pseudorapidity difference,transverse momentum difference, and p T average of SS and OS particle pairs, in various mul-tiplicity or centrality ranges of the collisions. The differences in correlations between OS andSS particles with respect to both second- and third-order event planes as functions of ∆ η andmultiplicity are found to agree for pPb and PbPb collisions, indicating a common underlyingmechanism for the two systems. Dividing the OS and SS difference of the three-particle cor-relator by the product of the v n harmonic of the corresponding order and the difference of thetwo-particle correlator, the ratios are found to be similar for the second- and third-order eventplanes, and show a weak dependence on event multiplicity. These observations support a sce-nario in which the charge-dependent three-particle correlator is predominantly a consequenceof charge-dependent two-particle correlations coupled to an anisotropic flow signal.To establish the relation between the three-particle correlator and anisotropic flow harmonic indetail, an event shape engineering technique is applied. A linear relation for the ratio of three-to two-particle correlator difference as a function of v is observed, which extrapolates to anintercept that is consistent with zero within uncertainties for most of multiplicities. An upperlimit on the v -independent fraction of the three-particle correlator, or the possible CME signalcontribution (assumed independent of v within the same narrow multiplicity or centralityrange), is estimated to be 13% for pPb data and 7% for PbPb data at a 95% confidence level. Thedata presented in this paper provide new stringent constraints on the nature of the backgroundcontribution to the charge-dependent azimuthal correlations, and establish a new baseline forthe search for the chiral magnetic effect in heavy ion collisions. trkoffline N no r m b - (Pb-going) c f pPb 8.16 TeV, PbPb 5.02 TeV Syst. uncer. s – s – CMS
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PbPb centrality(%)55 45 3565 | < 1.6 hD | Combinedlimits pPb PbPb
Figure 15: Extracted intercept parameter b norm (upper) and corresponding upper limit of thefraction of v -independent γ correlator component (lower), averaged over | ∆ η | < N offlinetrk in pPb collisions at √ s NN = Acknowledgments
We congratulate our colleagues in the CERN accelerator departments for the excellent perfor-mance of the LHC and thank the technical and administrative staffs at CERN and at otherCMS institutes for their contributions to the success of the CMS effort. In addition, we grate-fully acknowledge the computing centers and personnel of the Worldwide LHC ComputingGrid for delivering so effectively the computing infrastructure essential to our analyses. Fi-nally, we acknowledge the enduring support for the construction and operation of the LHCand the CMS detector provided by the following funding agencies: BMWFW and FWF (Aus-tria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria);CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia);RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Fin-land, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Ger-many); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI(Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM(Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (NewZealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON,RosAtom, RAS, RFBR and RAEP (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER(Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, andNSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (UnitedKingdom); DOE and NSF (USA).Individuals have received support from the Marie-Curie program and the European ResearchCouncil and Horizon 2020 Grant, contract No. 675440 (European Union); the Leventis Foun-dation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Fed-eral Science Policy Office; the Fonds pour la Formation `a la Recherche dans l’Industrie et dansl’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie(IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; theCouncil of Science and Industrial Research, India; the HOMING PLUS program of the Foun-dation for Polish Science, cofinanced from European Union, Regional Development Fund, theMobility Plus program of the Ministry of Science and Higher Education, the National ScienceCenter (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543,2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406; theNational Priorities Research Program by Qatar National Research Fund; the Programa Clar´ın-COFUND del Principado de Asturias; the Thalis and Aristeia programs cofinanced by EU-ESF and the Greek NSRF; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chula-longkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advance-ment Project (Thailand); and the Welch Foundation, contract C-1845.
AppendicesA General relation of v n harmonics, two- and three-particle az-imuthal correlations In Section 1, Eq. (5) can be derived in a way similar to Eq. (3), with details which can be foundin Ref. [24]. Here, a general derivation of Eq. (5) for all higher-order-harmonic correlators isgiven.Similar to Eq. (40) in Ref. [24], the general relation between the n th order anisotropy harmonic v n and the three-particle correlator with respect to the n th order event plane can be derived8
AppendicesA General relation of v n harmonics, two- and three-particle az-imuthal correlations In Section 1, Eq. (5) can be derived in a way similar to Eq. (3), with details which can be foundin Ref. [24]. Here, a general derivation of Eq. (5) for all higher-order-harmonic correlators isgiven.Similar to Eq. (40) in Ref. [24], the general relation between the n th order anisotropy harmonic v n and the three-particle correlator with respect to the n th order event plane can be derived8 starting from, γ n − n ≡ (cid:10) cos ( φ α + ( n − ) φ β − n Ψ n ) (cid:11) = (cid:82) ρ cos ( φ α + ( n − ) φ β − n Ψ n ) d φ α d φ β d x α d x β (cid:82) ρ d φ α d φ β d x α d x β = (cid:82) ρ cos (cid:0) φ α − φ β + n ( φ β − Ψ n ) (cid:1) d φ α d φ β d x α d x β (cid:82) ρ d φ α d φ β d x α d x β , (17)where x denotes ( p T , η ) and d x = p T d p T d η . ρ is the two-particle pair density distribution,which can be expressed in terms of the single-particle density distribution and its underlyingtwo-particle correlation function (see Section 2 in Ref. [24]), ρ = ρ ( φ α , x α ) ρ ( φ β , x β ) (cid:2) + C ( φ α , φ β , x α , x β ) (cid:3) . (18)In presence of collective anisotropy flow, the single-particle azimuthal distribution can be ex-pressed in terms of a Fourier series with respect to the event plane of the corresponding order, ρ ( φ , x ) = ρ ( x ) π (cid:34) + ∞ ∑ n = nv n ( x ) cos n ( φ − Ψ n ) (cid:35) , (19)where ρ ( x ) depends on p T and η only.The two-particle correlation function C describes intrinsic correlations that are insensitive tothe event plane Ψ n , but only involve azimuthal angle difference ∆ φ = φ α − φ β . It can be alsoexpanded in Fourier series [24], C ( ∆ φ , x α , x β ) = ∞ ∑ n = a n ( x α , x β ) cos ( n ∆ φ ) , (20)where a n ( x α , x β ) is the two-particle Fourier coefficient. By definition, a ( x α , x β ) is equal to thetwo-particle correlator δ ( x α , x β ) , introduced in Section 1, as a function of x α and x β (i.e., p T and η of both particles).Therefore, we substitute Eqs. (20) and (18) into (17) and obtain, γ n − n = N (cid:90) ρ ( x α ) ρ ( x β ) a ( x α , x β ) (cid:2) v n ( x α ) + v n ( x β ) (cid:3) d x α d x β = N (cid:90) ρ ( x α ) ρ ( x β ) δ ( x α , x β ) (cid:2) v n ( x α ) + v n ( x β ) (cid:3) d x α d x β (21)where N = (cid:82) ρ ( x ) dx . This is the general equation explaining why a nonzero two-particlecorrelation δ ( x α , x β ) plus an anisotropy flow of n th order v n ( x ) contribute to the three-particlecorrelator, γ n − n .Therefore, this general form of γ n − n can be applied to any order n and decomposed into thetwo-particle correlator δ and the n th order harmonic v n , where n = trkoffline N no r m b - - CMS
PbPb centrality(%)55 45 3565
PbPb 5.02 TeV < 5.0 q h hD | < -4.4 (default) c h -5.0 < < 5.0 c h Figure 16: The intercepts b norm of v -independent γ correlator component using particle c from HF + and HF − data, averaged over | ∆ η | < N offlinetrk in PbPbcollisions at √ s NN = B Supporting results of the event shape engineering method
As stated in Section 4.2, the Q vector is calculated using one side of the HF detector within the η range of 3 to 5 units. The default result in Section 5.2 presents the ∆ γ as a function of v ,where the particle c in the γ correlator corresponds to the η range − − c is reconstructed, as it is shownin Fig. 16.In Figs. 17 and 18, the denominators of Eq. (7), v c , for different Q classes with respect toHF + and HF − in PbPb collisions at √ s NN = v in the tracker region. Here v c is ameasure of elliptic anisotropy of the transverse energy registered in the HF detectors withoutbeing corrected to the particle-level elliptic flow. It serves as the resolution correction factorwhen deriving the three-particle correlators or the v values in the tracker region using thescalar-product method.In Fig. 19, the average N offlinetrk is shown as a function of v in different multiplicity and centralityranges in pPb (upper) and PbPb collisions (lower), respectively. The average N offlinetrk is foundto be weakly dependent on v , but with a slight decreasing trend as v increases. Similar toFig. 13, the effect at low multiplicities is stronger than that at high multiplicities. Overall, thiseffect is negligible for the results shown in Section 5.2. | < 2.4) h (| v , c v Cent. 30-35%PbPb 5.02 TeV < 5.0 q h | < 2.4) h (| v , c v Cent. 35-40%
CMS < 5.0 c h c h -5.0 < | < 2.4) h (| v , c v Cent. 40-45% | < 2.4) h (| v , c v Cent. 45-50% | < 2.4) h (| v , c v Cent. 50-60% | < 2.4) h (| v , c v Cent. 60-70%
Figure 17: The v c using particle c from HF + and HF − data are shown as a function of v inthe tracker region ( | η | < √ s NN = C Three- and two-particle correlator as functions of differentialvariables in different multiplicity and centrality classes
The figures in Appendix C show the γ , γ , and the δ correlators as a function of | ∆ η | , | ∆ p T | ,and p T in pPb collisions at √ s NN = N offlinetrk = [120,150), [150,185), [185,250),and [250,300) in Figs. 20 to 22. In PbPb collisions, the results are also shown for five centralityclasses from 30–80% in Figs. 23 to 25. | < 2.4) h (| v , c v trkoffline N £
120 pPb 8.16 TeV < 5.0 q h | < 2.4) h (| v , c v trkoffline N £ CMS | < 2.4) h (| v , c v trkoffline N £ | < 2.4) h (| v , c v trkoffline N £ Figure 18: The v c using particle c from the Pb-going side of the HF (4.4 < η < v in the tracker region ( | η | < √ s NN = | < 2.4) h (| v æ t r k o ff li ne N Æ CMS | < 1.6 hD |pPb 8.16 TeV < 400 trkoffline N £
300 < 300 trkoffline N £
250 < 250 trkoffline N £
185 < 185 trkoffline N £
150 < 150 trkoffline N £ | < 2.4) h (| v æ t r k o ff li ne N Æ · CMS
PbPb 5.02 TeV
Cent. 30-35%Cent. 35-40%Cent. 40-45%Cent. 45-50%Cent. 50-60%Cent. 60-70% | < 1.6 hD | Figure 19: The average multiplicity N offlinetrk as a function of v evaluated in each q class, fordifferent multiplicity ranges in pPb collisions at √ s NN = | hD | g - · pPb 8.16 TeV < 150 trkoffline N £ | hD | g - · (a)PbPb 5.02 TeV CMS < 150 trkoffline N £ | hD | g - - - · (Pb-going) c f (p-going) c f SS OS | hD | g - - - · | hD | d - · SS OS | hD | d - · | hD | g - · pPb 8.16 TeV < 185 trkoffline N £ | hD | g - · PbPb 5.02 TeV
CMS < 185 trkoffline N £
150 (b) | hD | g - - - - · (Pb-going) c f (p-going) c f SS OS | hD | g - - - - · | hD | d - · SS OS | hD | d - · | hD | g - - · pPb 8.16 TeV < 250 trkoffline N £ | hD | g - - · (c)PbPb 5.02 TeV CMS < 250 trkoffline N £ | hD | g - - - - · (Pb-going) c f (p-going) c f SS OS | hD | g - - - - · | hD | d - · SS OS | hD | d - · | hD | g - - · pPb 8.16 TeV < 300 trkoffline N £ | hD | g - - · PbPb 5.02 TeV
CMS < 300 trkoffline N £
250 (d) | hD | g - - - · (Pb-going) c f (p-going) c f SS OS | hD | g - - - · | hD | d - · SS OS | hD | d - · Figure 20: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ η | for four multiplicity ranges in pPb collisionsat √ s NN = c in Pb-going (solid markers) and p-going (open markers) sides are shown separately.The SS and OS two-particle correlators are denoted by different markers for both pPb and PbPbcollisions. Statistical and systematic uncertainties are indicated by the error bars and shadedregions, respectively. | T p D | g - · pPb 8.16 TeV < 150 trkoffline N £ | T p D | g - · (a)PbPb 5.02 TeV CMS < 150 trkoffline N £ | (GeV) T p D | g - - · (Pb-going) c f (p-going) c f SS OS | (GeV) T p D | g - - · | (GeV) T p D | d - - · SS OS | (GeV) T p D | d - - · | T p D | g - · pPb 8.16 TeV < 185 trkoffline N £ | T p D | g - · (b)PbPb 5.02 TeV CMS < 185 trkoffline N £ | (GeV) T p D | g - - - - · (Pb-going) c f (p-going) c f SS OS | (GeV) T p D | g - - - - · | (GeV) T p D | d - - · SS OS | (GeV) T p D | d - - · | T p D | g - · pPb 8.16 TeV < 250 trkoffline N £ | T p D | g - · (c)PbPb 5.02 TeV CMS < 250 trkoffline N £ | (GeV) T p D | g - - - · (Pb-going) c f (p-going) c f SS OS | (GeV) T p D | g - - - · | (GeV) T p D | d - · SS OS | (GeV) T p D | d - · | T p D | g - · pPb 8.16 TeV < 300 trkoffline N £ | T p D | g - · (d)PbPb 5.02 TeV CMS < 300 trkoffline N £ | (GeV) T p D | g - - - · (Pb-going) c f (p-going) c f SS OS | (GeV) T p D | g - - - · | (GeV) T p D | d - - · SS OS | (GeV) T p D | d - - · Figure 21: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ p T | for four multiplicity ranges in pPb collisionsat √ s NN = c in Pb-going (solid markers) and p-going (open markers) sides are shownseparately. The SS and OS two-particle correlators are denoted by different markers for bothpPb and PbPb collisions. Statistical and systematic uncertainties are indicated by the error barsand shaded regions, respectively. (GeV) T p g - - · pPb 8.16 TeV < 150 trkoffline N £ (GeV) T p g - - · (a)PbPb 5.02 TeV CMS < 150 trkoffline N £ (GeV) T p g - - - - · (Pb-going) c f (p-going) c f SS OS (GeV) T p g - - - - · (GeV) T p d - · SS OS (GeV) T p d - · (GeV) T p g - · pPb 8.16 TeV < 185 trkoffline N £ (GeV) T p g - · (b)PbPb 5.02 TeV CMS < 185 trkoffline N £ (GeV) T p g - - - · (Pb-going) c f (p-going) c f SS OS (GeV) T p g - - - · (GeV) T p d - · SS OS (GeV) T p d - · (GeV) T p g - · pPb 8.16 TeV < 250 trkoffline N £ (GeV) T p g - · (c)PbPb 5.02 TeV CMS < 250 trkoffline N £ (GeV) T p g - - - - · (Pb-going) c f (p-going) c f SS OS (GeV) T p g - - - - · (GeV) T p d - · SS OS (GeV) T p d - · (GeV) T p g - · pPb 8.16 TeV < 300 trkoffline N £ (GeV) T p g - · (d)PbPb 5.02 TeV CMS < 300 trkoffline N £ (GeV) T p g - - - - · (Pb-going) c f (p-going) c f SS OS (GeV) T p g - - - - · (GeV) T p d - · SS OS (GeV) T p d - · Figure 22: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of p T for four multiplicity ranges in pPb collisions at √ s NN = √ s NN = c in Pb-going (solid markers) and p-going (open markers) sides are shown sepa-rately. The SS and OS two-particle correlators are denoted by different markers for both pPband PbPb collisions. Statistical and systematic uncertainties are indicated by the error bars andshaded regions, respectively. | hD | g - - · (a)Cent. 30-40%PbPb 5.02 TeV CMS | hD | g - - · SS OS | hD | d - · SS OS | hD | g - - · (b)Cent. 40-50%PbPb 5.02 TeV CMS | hD | g - - · SS OS | hD | d - · SS OS | hD | g - - · (c)Cent. 50-60%PbPb 5.02 TeV CMS | hD | g - - - · SS OS | hD | d - · SS OS | hD | g - - · (d)Cent. 60-70%PbPb 5.02 TeV CMS | hD | g - - - · SS OS | hD | d - - · SS OS | hD | g - - · (e)Cent. 70-80%PbPb 5.02 TeV CMS | hD | g - - - · SS OS | hD | d - - · SS OS
Figure 23: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ η | for five centrality classes in PbPb collisions at5.02 TeV. The SS and OS two-particle correlators are denoted by different markers. Statisticaland systematic uncertainties are indicated by the error bars and shaded regions, respectively. | T p D | g - - · (a)Cent. 30-40%PbPb 5.02 TeV CMS | (GeV) T p D | g - - - · SS OS | (GeV) T p D | d - · SS OS | T p D | g - - · (b)PbPb 5.02 TeV CMS
Cent. 40-50% | (GeV) T p D | g - - - · SS OS | (GeV) T p D | d - · SS OS | T p D | g - - · (c)PbPb 5.02 TeV CMS
Cent. 50-60% | (GeV) T p D | g - - - - · SS OS | (GeV) T p D | d - - · SS OS | T p D | g - - · (d)PbPb 5.02 TeV CMS
Cent. 60-70% | (GeV) T p D | g - - - · SS OS | (GeV) T p D | d - - · SS OS | T p D | g - · (e)PbPb 5.02 TeV CMS
Cent. 70-80% | (GeV) T p D | g - - - · SS OS | (GeV) T p D | d - - · SS OS
Figure 24: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ p T | for five centrality classes in PbPb collisionsat √ s NN =8
Figure 24: The SS and OS three-particle correlators, γ (upper) and γ (middle), and two-particle correlator, δ (lower), as a function of | ∆ p T | for five centrality classes in PbPb collisionsat √ s NN =8 (GeV) T p g - - · (a)PbPb 5.02 TeV CMS
Cent. 30-40% (GeV) T p g - - - · SS OS (GeV) T p d - · SS OS (GeV) T p g - - · (b)PbPb 5.02 TeV CMS
Cent. 40-50% (GeV) T p g - - - · SS OS (GeV) T p d - · SS OS (GeV) T p g - - · (c)PbPb 5.02 TeV CMS
Cent. 50-60% (GeV) T p g - - · SS OS (GeV) T p d - - · SS OS (GeV) T p g - - · (d)PbPb 5.02 TeV CMS
Cent. 60-70% (GeV) T p g - - · SS OS (GeV) T p d - · SS OS (GeV) T p g - · (e)PbPb 5.02 TeV CMS
Cent. 70-80% (GeV) T p g - - · SS OS (GeV) T p d - · SS OS
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Yerevan Physics Institute, Yerevan, Armenia
A.M. Sirunyan, A. Tumasyan
Institut f ¨ur Hochenergiephysik, Wien, Austria
W. Adam, F. Ambrogi, E. Asilar, T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Er ¨o,M. Flechl, M. Friedl, R. Fr ¨uhwirth , V.M. Ghete, J. Grossmann, J. Hrubec, M. Jeitler , A. K ¨onig,N. Krammer, I. Kr¨atschmer, D. Liko, T. Madlener, I. Mikulec, E. Pree, N. Rad, H. Rohringer,J. Schieck , R. Sch ¨ofbeck, M. Spanring, D. Spitzbart, W. Waltenberger, J. Wittmann, C.-E. Wulz ,M. Zarucki Institute for Nuclear Problems, Minsk, Belarus
V. Chekhovsky, V. Mossolov, J. Suarez Gonzalez
Universiteit Antwerpen, Antwerpen, Belgium
E.A. De Wolf, D. Di Croce, X. Janssen, J. Lauwers, H. Van Haevermaet, P. Van Mechelen, N. VanRemortel
Vrije Universiteit Brussel, Brussel, Belgium
S. Abu Zeid, F. Blekman, J. D’Hondt, I. De Bruyn, J. De Clercq, K. Deroover, G. Flouris,D. Lontkovskyi, S. Lowette, S. Moortgat, L. Moreels, Q. Python, K. Skovpen, S. Tavernier,W. Van Doninck, P. Van Mulders, I. Van Parijs
Universit´e Libre de Bruxelles, Bruxelles, Belgium
D. Beghin, H. Brun, B. Clerbaux, G. De Lentdecker, H. Delannoy, B. Dorney, G. Fasanella,L. Favart, R. Goldouzian, A. Grebenyuk, G. Karapostoli, T. Lenzi, J. Luetic, T. Maerschalk,A. Marinov, A. Randle-conde, T. Seva, E. Starling, C. Vander Velde, P. Vanlaer, D. Vannerom,R. Yonamine, F. Zenoni, F. Zhang Ghent University, Ghent, Belgium
A. Cimmino, T. Cornelis, D. Dobur, A. Fagot, M. Gul, I. Khvastunov , D. Poyraz, C. Roskas,S. Salva, M. Tytgat, W. Verbeke, N. Zaganidis Universit´e Catholique de Louvain, Louvain-la-Neuve, Belgium
H. Bakhshiansohi, O. Bondu, S. Brochet, G. Bruno, C. Caputo, A. Caudron, P. David, S. DeVisscher, C. Delaere, M. Delcourt, B. Francois, A. Giammanco, M. Komm, G. Krintiras,V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, K. Piotrzkowski, L. Quertenmont, A. Saggio,M. Vidal Marono, S. Wertz, J. Zobec
Universit´e de Mons, Mons, Belgium
N. Beliy
Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil
W.L. Ald´a J ´unior, F.L. Alves, G.A. Alves, L. Brito, M. Correa Martins Junior, C. Hensel,A. Moraes, M.E. Pol, P. Rebello Teles
Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
E. Belchior Batista Das Chagas, W. Carvalho, J. Chinellato , E. Coelho, E.M. Da Costa, G.G. DaSilveira , D. De Jesus Damiao, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson,M. Melo De Almeida, C. Mora Herrera, L. Mundim, H. Nogima, L.J. Sanchez Rosas, A. Santoro,A. Sznajder, M. Thiel, E.J. Tonelli Manganote , F. Torres Da Silva De Araujo, A. Vilela Pereira Universidade Estadual Paulista a , Universidade Federal do ABC b , S˜ao Paulo, Brazil S. Ahuja a , C.A. Bernardes a , T.R. Fernandez Perez Tomei a , E.M. Gregores b , P.G. Mercadante b ,S.F. Novaes a , Sandra S. Padula a , D. Romero Abad b , J.C. Ruiz Vargas a Institute for Nuclear Research and Nuclear Energy of Bulgaria Academy of Sciences
A. Aleksandrov, R. Hadjiiska, P. Iaydjiev, M. Misheva, M. Rodozov, M. Shopova, G. Sultanov
University of Sofia, Sofia, Bulgaria
A. Dimitrov, I. Glushkov, L. Litov, B. Pavlov, P. Petkov
Beihang University, Beijing, China
W. Fang , X. Gao , L. Yuan Institute of High Energy Physics, Beijing, China
M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen, M. Chen, Y. Chen, C.H. Jiang, D. Leggat, H. Liao,Z. Liu, F. Romeo, S.M. Shaheen, A. Spiezia, J. Tao, C. Wang, Z. Wang, E. Yazgan, H. Zhang,S. Zhang, J. Zhao
State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
Y. Ban, G. Chen, Q. Li, S. Liu, Y. Mao, S.J. Qian, D. Wang, Z. Xu
Universidad de Los Andes, Bogota, Colombia
C. Avila, A. Cabrera, L.F. Chaparro Sierra, C. Florez, C.F. Gonz´alez Hern´andez, J.D. RuizAlvarez
University of Split, Faculty of Electrical Engineering, Mechanical Engineering and NavalArchitecture, Split, Croatia
B. Courbon, N. Godinovic, D. Lelas, I. Puljak, P.M. Ribeiro Cipriano, T. Sculac
University of Split, Faculty of Science, Split, Croatia
Z. Antunovic, M. Kovac
Institute Rudjer Boskovic, Zagreb, Croatia
V. Brigljevic, D. Ferencek, K. Kadija, B. Mesic, A. Starodumov , T. Susa University of Cyprus, Nicosia, Cyprus
M.W. Ather, A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis,H. Rykaczewski
Charles University, Prague, Czech Republic
M. Finger , M. Finger Jr. Universidad San Francisco de Quito, Quito, Ecuador
E. Carrera Jarrin
Academy of Scientific Research and Technology of the Arab Republic of Egypt, EgyptianNetwork of High Energy Physics, Cairo, Egypt
Y. Assran , S. Elgammal , A. Mahrous National Institute of Chemical Physics and Biophysics, Tallinn, Estonia
R.K. Dewanjee, M. Kadastik, L. Perrini, M. Raidal, A. Tiko, C. Veelken
Department of Physics, University of Helsinki, Helsinki, Finland
P. Eerola, H. Kirschenmann, J. Pekkanen, M. Voutilainen Helsinki Institute of Physics, Helsinki, Finland
T. J¨arvinen, V. Karim¨aki, R. Kinnunen, T. Lamp´en, K. Lassila-Perini, S. Lehti, T. Lind´en,P. Luukka, E. Tuominen, J. Tuominiemi
Lappeenranta University of Technology, Lappeenranta, Finland
J. Talvitie, T. Tuuva
IRFU, CEA, Universit´e Paris-Saclay, Gif-sur-Yvette, France
M. Besancon, F. Couderc, M. Dejardin, D. Denegri, J.L. Faure, F. Ferri, S. Ganjour, S. Ghosh,A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, I. Kucher, C. Leloup, E. Locci,M. Machet, J. Malcles, G. Negro, J. Rander, A. Rosowsky, M. ¨O. Sahin, M. Titov
Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Universit´e Paris-Saclay,Palaiseau, France
A. Abdulsalam, C. Amendola, I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro,C. Charlot, R. Granier de Cassagnac, M. Jo, S. Lisniak, A. Lobanov, J. Martin Blanco, M. Nguyen,C. Ochando, G. Ortona, P. Paganini, P. Pigard, R. Salerno, J.B. Sauvan, Y. Sirois, A.G. StahlLeiton, T. Strebler, Y. Yilmaz, A. Zabi, A. Zghiche
Universit´e de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
J.-L. Agram , J. Andrea, D. Bloch, J.-M. Brom, M. Buttignol, E.C. Chabert, N. Chanon,C. Collard, E. Conte , X. Coubez, J.-C. Fontaine , D. Gel´e, U. Goerlach, M. Jansov´a, A.-C. LeBihan, N. Tonon, P. Van Hove Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules,CNRS/IN2P3, Villeurbanne, France
S. Gadrat
Universit´e de Lyon, Universit´e Claude Bernard Lyon 1, CNRS-IN2P3, Institut de PhysiqueNucl´eaire de Lyon, Villeurbanne, France
S. Beauceron, C. Bernet, G. Boudoul, R. Chierici, D. Contardo, P. Depasse, H. El Mamouni,J. Fay, L. Finco, S. Gascon, M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh,M. Lethuillier, L. Mirabito, A.L. Pequegnot, S. Perries, A. Popov , V. Sordini, M. VanderDonckt, S. Viret Georgian Technical University, Tbilisi, Georgia
A. Khvedelidze Tbilisi State University, Tbilisi, Georgia
Z. Tsamalaidze RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany
C. Autermann, L. Feld, M.K. Kiesel, K. Klein, M. Lipinski, M. Preuten, C. Schomakers, J. Schulz,V. Zhukov RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany
A. Albert, E. Dietz-Laursonn, D. Duchardt, M. Endres, M. Erdmann, S. Erdweg, T. Esch,R. Fischer, A. G ¨uth, M. Hamer, T. Hebbeker, C. Heidemann, K. Hoepfner, S. Knutzen,M. Merschmeyer, A. Meyer, P. Millet, S. Mukherjee, T. Pook, M. Radziej, H. Reithler, M. Rieger,F. Scheuch, D. Teyssier, S. Th ¨uer
RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany
G. Fl ¨ugge, B. Kargoll, T. Kress, A. K ¨unsken, T. M ¨uller, A. Nehrkorn, A. Nowack, C. Pistone,O. Pooth, A. Stahl Deutsches Elektronen-Synchrotron, Hamburg, Germany
M. Aldaya Martin, T. Arndt, C. Asawatangtrakuldee, K. Beernaert, O. Behnke, U. Behrens,A. Berm ´udez Mart´ınez, A.A. Bin Anuar, K. Borras , V. Botta, A. Campbell, P. Connor,C. Contreras-Campana, F. Costanza, C. Diez Pardos, G. Eckerlin, D. Eckstein, T. Eichhorn,E. Eren, E. Gallo , J. Garay Garcia, A. Geiser, A. Gizhko, J.M. Grados Luyando, A. Grohsjean,P. Gunnellini, M. Guthoff, A. Harb, J. Hauk, M. Hempel , H. Jung, A. Kalogeropoulos,M. Kasemann, J. Keaveney, C. Kleinwort, I. Korol, D. Kr ¨ucker, W. Lange, A. Lelek, T. Lenz,J. Leonard, K. Lipka, W. Lohmann , R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag,J. Mnich, A. Mussgiller, E. Ntomari, D. Pitzl, A. Raspereza, B. Roland, M. Savitskyi, P. Saxena,R. Shevchenko, S. Spannagel, N. Stefaniuk, G.P. Van Onsem, R. Walsh, Y. Wen, K. Wichmann,C. Wissing, O. Zenaiev University of Hamburg, Hamburg, Germany
R. Aggleton, S. Bein, V. Blobel, M. Centis Vignali, T. Dreyer, E. Garutti, D. Gonzalez, J. Haller,A. Hinzmann, M. Hoffmann, A. Karavdina, R. Klanner, R. Kogler, N. Kovalchuk, S. Kurz,T. Lapsien, I. Marchesini, D. Marconi, M. Meyer, M. Niedziela, D. Nowatschin, F. Pantaleo ,T. Peiffer, A. Perieanu, C. Scharf, P. Schleper, A. Schmidt, S. Schumann, J. Schwandt,J. Sonneveld, H. Stadie, G. Steinbr ¨uck, F.M. Stober, M. St ¨over, H. Tholen, D. Troendle, E. Usai,L. Vanelderen, A. Vanhoefer, B. Vormwald Institut f ¨ur Experimentelle Kernphysik, Karlsruhe, Germany
M. Akbiyik, C. Barth, S. Baur, E. Butz, R. Caspart, T. Chwalek, F. Colombo, W. De Boer,A. Dierlamm, B. Freund, R. Friese, M. Giffels, D. Haitz, M.A. Harrendorf, F. Hartmann ,S.M. Heindl, U. Husemann, F. Kassel , S. Kudella, H. Mildner, M.U. Mozer, Th. M ¨uller,M. Plagge, G. Quast, K. Rabbertz, M. Schr ¨oder, I. Shvetsov, G. Sieber, H.J. Simonis, R. Ulrich,S. Wayand, M. Weber, T. Weiler, S. Williamson, C. W ¨ohrmann, R. Wolf Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi,Greece
G. Anagnostou, G. Daskalakis, T. Geralis, V.A. Giakoumopoulou, A. Kyriakis, D. Loukas,I. Topsis-Giotis
National and Kapodistrian University of Athens, Athens, Greece
G. Karathanasis, S. Kesisoglou, A. Panagiotou, N. Saoulidou
National Technical University of Athens, Athens, Greece
K. Kousouris
University of Io´annina, Io´annina, Greece
I. Evangelou, C. Foudas, P. Kokkas, S. Mallios, N. Manthos, I. Papadopoulos, E. Paradas,J. Strologas, F.A. Triantis
MTA-ELTE Lend ¨ulet CMS Particle and Nuclear Physics Group, E ¨otv ¨os Lor´and University,Budapest, Hungary
M. Csanad, N. Filipovic, G. Pasztor, O. Sur´anyi, G.I. Veres Wigner Research Centre for Physics, Budapest, Hungary
G. Bencze, C. Hajdu, D. Horvath , ´A. Hunyadi, F. Sikler, V. Veszpremi, A.J. Zsigmond Institute of Nuclear Research ATOMKI, Debrecen, Hungary
N. Beni, S. Czellar, J. Karancsi , A. Makovec, J. Molnar, Z. Szillasi Institute of Physics, University of Debrecen, Debrecen, Hungary
M. Bart ´ok , P. Raics, Z.L. Trocsanyi, B. Ujvari Indian Institute of Science (IISc), Bangalore, India
S. Choudhury, J.R. Komaragiri
National Institute of Science Education and Research, Bhubaneswar, India
S. Bahinipati , S. Bhowmik, P. Mal, K. Mandal, A. Nayak , D.K. Sahoo , N. Sahoo, S.K. Swain Panjab University, Chandigarh, India
S. Bansal, S.B. Beri, V. Bhatnagar, R. Chawla, N. Dhingra, A.K. Kalsi, A. Kaur, M. Kaur, S. Kaur,R. Kumar, P. Kumari, A. Mehta, J.B. Singh, G. Walia
University of Delhi, Delhi, India
Ashok Kumar, Aashaq Shah, A. Bhardwaj, S. Chauhan, B.C. Choudhary, R.B. Garg, S. Keshri,A. Kumar, S. Malhotra, M. Naimuddin, K. Ranjan, R. Sharma
Saha Institute of Nuclear Physics, HBNI, Kolkata, India
R. Bhardwaj, R. Bhattacharya, S. Bhattacharya, U. Bhawandeep, S. Dey, S. Dutt, S. Dutta,S. Ghosh, N. Majumdar, A. Modak, K. Mondal, S. Mukhopadhyay, S. Nandan, A. Purohit,A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar, M. Sharan, S. Thakur
Indian Institute of Technology Madras, Madras, India
P.K. Behera
Bhabha Atomic Research Centre, Mumbai, India
R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty , P.K. Netrakanti, L.M. Pant,P. Shukla, A. Topkar Tata Institute of Fundamental Research-A, Mumbai, India
T. Aziz, S. Dugad, B. Mahakud, S. Mitra, G.B. Mohanty, N. Sur, B. Sutar
Tata Institute of Fundamental Research-B, Mumbai, India
S. Banerjee, S. Bhattacharya, S. Chatterjee, P. Das, M. Guchait, Sa. Jain, S. Kumar, M. Maity ,G. Majumder, K. Mazumdar, T. Sarkar , N. Wickramage Indian Institute of Science Education and Research (IISER), Pune, India
S. Chauhan, S. Dube, V. Hegde, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, S. Sharma
Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
S. Chenarani , E. Eskandari Tadavani, S.M. Etesami , M. Khakzad, M. MohammadiNajafabadi, M. Naseri, S. Paktinat Mehdiabadi , F. Rezaei Hosseinabadi, B. Safarzadeh ,M. Zeinali University College Dublin, Dublin, Ireland
M. Felcini, M. Grunewald
INFN Sezione di Bari a , Universit`a di Bari b , Politecnico di Bari c , Bari, Italy M. Abbrescia a , b , C. Calabria a , b , A. Colaleo a , D. Creanza a , c , L. Cristella a , b , N. De Filippis a , c ,M. De Palma a , b , F. Errico a , b , L. Fiore a , G. Iaselli a , c , S. Lezki a , b , G. Maggi a , c , M. Maggi a ,G. Miniello a , b , S. My a , b , S. Nuzzo a , b , A. Pompili a , b , G. Pugliese a , c , R. Radogna a , A. Ranieri a ,G. Selvaggi a , b , A. Sharma a , L. Silvestris a ,14 , R. Venditti a , P. Verwilligen a INFN Sezione di Bologna a , Universit`a di Bologna b , Bologna, Italy G. Abbiendi a , C. Battilana a , b , D. Bonacorsi a , b , L. Borgonovi a , b , S. Braibant-Giacomelli a , b ,R. Campanini a , b , P. Capiluppi a , b , A. Castro a , b , F.R. Cavallo a , S.S. Chhibra a , G. Codispoti a , b ,M. Cuffiani a , b , G.M. Dallavalle a , F. Fabbri a , A. Fanfani a , b , D. Fasanella a , b , P. Giacomelli a ,C. Grandi a , L. Guiducci a , b , S. Marcellini a , G. Masetti a , A. Montanari a , F.L. Navarria a , b ,A. Perrotta a , A.M. Rossi a , b , T. Rovelli a , b , G.P. Siroli a , b , N. Tosi a8
INFN Sezione di Bari a , Universit`a di Bari b , Politecnico di Bari c , Bari, Italy M. Abbrescia a , b , C. Calabria a , b , A. Colaleo a , D. Creanza a , c , L. Cristella a , b , N. De Filippis a , c ,M. De Palma a , b , F. Errico a , b , L. Fiore a , G. Iaselli a , c , S. Lezki a , b , G. Maggi a , c , M. Maggi a ,G. Miniello a , b , S. My a , b , S. Nuzzo a , b , A. Pompili a , b , G. Pugliese a , c , R. Radogna a , A. Ranieri a ,G. Selvaggi a , b , A. Sharma a , L. Silvestris a ,14 , R. Venditti a , P. Verwilligen a INFN Sezione di Bologna a , Universit`a di Bologna b , Bologna, Italy G. Abbiendi a , C. Battilana a , b , D. Bonacorsi a , b , L. Borgonovi a , b , S. Braibant-Giacomelli a , b ,R. Campanini a , b , P. Capiluppi a , b , A. Castro a , b , F.R. Cavallo a , S.S. Chhibra a , G. Codispoti a , b ,M. Cuffiani a , b , G.M. Dallavalle a , F. Fabbri a , A. Fanfani a , b , D. Fasanella a , b , P. Giacomelli a ,C. Grandi a , L. Guiducci a , b , S. Marcellini a , G. Masetti a , A. Montanari a , F.L. Navarria a , b ,A. Perrotta a , A.M. Rossi a , b , T. Rovelli a , b , G.P. Siroli a , b , N. Tosi a8 INFN Sezione di Catania a , Universit`a di Catania b , Catania, Italy S. Albergo a , b , S. Costa a , b , A. Di Mattia a , F. Giordano a , b , R. Potenza a , b , A. Tricomi a , b , C. Tuve a , b INFN Sezione di Firenze a , Universit`a di Firenze b , Firenze, Italy G. Barbagli a , K. Chatterjee a , b , V. Ciulli a , b , C. Civinini a , R. D’Alessandro a , b , E. Focardi a , b ,P. Lenzi a , b , M. Meschini a , S. Paoletti a , L. Russo a ,28 , G. Sguazzoni a , D. Strom a , L. Viliani a , b ,14 INFN Laboratori Nazionali di Frascati, Frascati, Italy
L. Benussi, S. Bianco, F. Fabbri, D. Piccolo, F. Primavera INFN Sezione di Genova a , Universit`a di Genova b , Genova, Italy V. Calvelli a , b , F. Ferro a , E. Robutti a , S. Tosi a , b INFN Sezione di Milano-Bicocca a , Universit`a di Milano-Bicocca b , Milano, Italy A. Benaglia a , L. Brianza a , b , F. Brivio a , b , V. Ciriolo a , b , M.E. Dinardo a , b , S. Fiorendi a , b , S. Gennai a ,A. Ghezzi a , b , P. Govoni a , b , M. Malberti a , b , S. Malvezzi a , R.A. Manzoni a , b , D. Menasce a ,L. Moroni a , M. Paganoni a , b , K. Pauwels a , b , D. Pedrini a , S. Pigazzini a , b ,29 , S. Ragazzi a , b ,N. Redaelli a , T. Tabarelli de Fatis a , b INFN Sezione di Napoli a , Universit`a di Napoli ’Federico II’ b , Napoli, Italy, Universit`a dellaBasilicata c , Potenza, Italy, Universit`a G. Marconi d , Roma, Italy S. Buontempo a , N. Cavallo a , c , S. Di Guida a , d ,14 , F. Fabozzi a , c , F. Fienga a , b , A.O.M. Iorio a , b ,W.A. Khan a , L. Lista a , S. Meola a , d ,14 , P. Paolucci a ,14 , C. Sciacca a , b , F. Thyssen a INFN Sezione di Padova a , Universit`a di Padova b , Padova, Italy, Universit`a di Trento c ,Trento, Italy P. Azzi a , N. Bacchetta a , L. Benato a , b , M. Biasotto a ,30 , D. Bisello a , b , A. Boletti a , b , R. Carlin a , b ,P. Checchia a , M. Dall’Osso a , b , P. De Castro Manzano a , T. Dorigo a , U. Dosselli a , F. Gasparini a , b ,U. Gasparini a , b , S. Lacaprara a , P. Lujan, M. Margoni a , b , A.T. Meneguzzo a , b , N. Pozzobon a , b ,P. Ronchese a , b , R. Rossin a , b , F. Simonetto a , b , E. Torassa a , M. Zanetti a , b , P. Zotto a , b , G. Zumerle a , b INFN Sezione di Pavia a , Universit`a di Pavia b , Pavia, Italy A. Braghieri a , A. Magnani a , P. Montagna a , b , S.P. Ratti a , b , V. Re a , M. Ressegotti a , b , C. Riccardi a , b ,P. Salvini a , I. Vai a , b , P. Vitulo a , b INFN Sezione di Perugia a , Universit`a di Perugia b , Perugia, Italy L. Alunni Solestizi a , b , M. Biasini a , b , G.M. Bilei a , C. Cecchi a , b , D. Ciangottini a , b , L. Fan `o a , b ,P. Lariccia a , b , R. Leonardi a , b , E. Manoni a , G. Mantovani a , b , V. Mariani a , b , M. Menichelli a ,A. Rossi a , b , A. Santocchia a , b , D. Spiga a INFN Sezione di Pisa a , Universit`a di Pisa b , Scuola Normale Superiore di Pisa c , Pisa, Italy K. Androsov a , P. Azzurri a ,14 , G. Bagliesi a , T. Boccali a , L. Borrello, R. Castaldi a , M.A. Ciocci a , b ,R. Dell’Orso a , G. Fedi a , L. Giannini a , c , A. Giassi a , M.T. Grippo a ,28 , F. Ligabue a , c , T. Lomtadze a ,E. Manca a , c , G. Mandorli a , c , L. Martini a , b , A. Messineo a , b , F. Palla a , A. Rizzi a , b , A. Savoy-Navarro a ,31 , P. Spagnolo a , R. Tenchini a , G. Tonelli a , b , A. Venturi a , P.G. Verdini a INFN Sezione di Roma a , Sapienza Universit`a di Roma b , Rome, Italy L. Barone a , b , F. Cavallari a , M. Cipriani a , b , N. Daci a , D. Del Re a , b ,14 , E. Di Marco a , b , M. Diemoz a ,S. Gelli a , b , E. Longo a , b , F. Margaroli a , b , B. Marzocchi a , b , P. Meridiani a , G. Organtini a , b ,R. Paramatti a , b , F. Preiato a , b , S. Rahatlou a , b , C. Rovelli a , F. Santanastasio a , b INFN Sezione di Torino a , Universit`a di Torino b , Torino, Italy, Universit`a del PiemonteOrientale c , Novara, Italy N. Amapane a , b , R. Arcidiacono a , c , S. Argiro a , b , M. Arneodo a , c , N. Bartosik a , R. Bellan a , b ,C. Biino a , N. Cartiglia a , F. Cenna a , b , M. Costa a , b , R. Covarelli a , b , A. Degano a , b , N. Demaria a , B. Kiani a , b , C. Mariotti a , S. Maselli a , E. Migliore a , b , V. Monaco a , b , E. Monteil a , b , M. Monteno a ,M.M. Obertino a , b , L. Pacher a , b , N. Pastrone a , M. Pelliccioni a , G.L. Pinna Angioni a , b , F. Ravera a , b ,A. Romero a , b , M. Ruspa a , c , R. Sacchi a , b , K. Shchelina a , b , V. Sola a , A. Solano a , b , A. Staiano a ,P. Traczyk a , b INFN Sezione di Trieste a , Universit`a di Trieste b , Trieste, Italy S. Belforte a , M. Casarsa a , F. Cossutti a , G. Della Ricca a , b , A. Zanetti a Kyungpook National University, Daegu, Korea
D.H. Kim, G.N. Kim, M.S. Kim, J. Lee, S. Lee, S.W. Lee, C.S. Moon, Y.D. Oh, S. Sekmen, D.C. Son,Y.C. Yang
Chonbuk National University, Jeonju, Korea
A. Lee
Chonnam National University, Institute for Universe and Elementary Particles, Kwangju,Korea
H. Kim, D.H. Moon, G. Oh
Hanyang University, Seoul, Korea
J.A. Brochero Cifuentes, J. Goh, T.J. Kim
Korea University, Seoul, Korea
S. Cho, S. Choi, Y. Go, D. Gyun, S. Ha, B. Hong, Y. Jo, Y. Kim, K. Lee, K.S. Lee, S. Lee, J. Lim,S.K. Park, Y. Roh
Seoul National University, Seoul, Korea
J. Almond, J. Kim, J.S. Kim, H. Lee, K. Lee, K. Nam, S.B. Oh, B.C. Radburn-Smith, S.h. Seo,U.K. Yang, H.D. Yoo, G.B. Yu
University of Seoul, Seoul, Korea
M. Choi, H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park
Sungkyunkwan University, Suwon, Korea
Y. Choi, C. Hwang, J. Lee, I. Yu
Vilnius University, Vilnius, Lithuania
V. Dudenas, A. Juodagalvis, J. Vaitkus
National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia
I. Ahmed, Z.A. Ibrahim, M.A.B. Md Ali , F. Mohamad Idris , W.A.T. Wan Abdullah,M.N. Yusli, Z. Zolkapli Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico
Reyes-Almanza, R, Ramirez-Sanchez, G., Duran-Osuna, M. C., H. Castilla-Valdez, E. De LaCruz-Burelo, I. Heredia-De La Cruz , Rabadan-Trejo, R. I., R. Lopez-Fernandez, J. MejiaGuisao, A. Sanchez-Hernandez Universidad Iberoamericana, Mexico City, Mexico
S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia
Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada
Universidad Aut ´onoma de San Luis Potos´ı, San Luis Potos´ı, Mexico
A. Morelos Pineda University of Auckland, Auckland, New Zealand
D. Krofcheck
University of Canterbury, Christchurch, New Zealand
P.H. Butler
National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan
A. Ahmad, M. Ahmad, Q. Hassan, H.R. Hoorani, A. Saddique, M.A. Shah, M. Shoaib, M. Waqas
National Centre for Nuclear Research, Swierk, Poland
H. Bialkowska, M. Bluj, B. Boimska, T. Frueboes, M. G ´orski, M. Kazana, K. Nawrocki,M. Szleper, P. Zalewski
Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
K. Bunkowski, A. Byszuk , K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura,M. Olszewski, A. Pyskir, M. Walczak Laborat ´orio de Instrumenta¸c˜ao e F´ısica Experimental de Part´ıculas, Lisboa, Portugal
P. Bargassa, C. Beir˜ao Da Cruz E Silva, A. Di Francesco, P. Faccioli, B. Galinhas, M. Gallinaro,J. Hollar, N. Leonardo, L. Lloret Iglesias, M.V. Nemallapudi, J. Seixas, G. Strong, O. Toldaiev,D. Vadruccio, J. Varela
Joint Institute for Nuclear Research, Dubna, Russia
S. Afanasiev, P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin,A. Lanev, A. Malakhov, V. Matveev , V. Palichik, V. Perelygin, S. Shmatov, S. Shulha,N. Skatchkov, V. Smirnov, N. Voytishin, A. Zarubin
Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia
Y. Ivanov, V. Kim , E. Kuznetsova , P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov,V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev Institute for Nuclear Research, Moscow, Russia
Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu, M. Kirsanov, N. Krasnikov,A. Pashenkov, D. Tlisov, A. Toropin
Institute for Theoretical and Experimental Physics, Moscow, Russia
V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, I. Pozdnyakov, G. Safronov,A. Spiridonov, A. Stepennov, M. Toms, E. Vlasov, A. Zhokin
Moscow Institute of Physics and Technology, Moscow, Russia
T. Aushev, A. Bylinkin National Research Nuclear University ’Moscow Engineering Physics Institute’ (MEPhI),Moscow, Russia
R. Chistov , M. Danilov , P. Parygin, D. Philippov, S. Polikarpov, E. Tarkovskii P.N. Lebedev Physical Institute, Moscow, Russia
V. Andreev, M. Azarkin , I. Dremin , M. Kirakosyan , A. Terkulov Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow,Russia
A. Baskakov, A. Belyaev, E. Boos, A. Ershov, A. Gribushin, A. Kaminskiy , O. Kodolova,V. Korotkikh, I. Lokhtin, I. Miagkov, S. Obraztsov, S. Petrushanko, V. Savrin, A. Snigirev,I. Vardanyan Novosibirsk State University (NSU), Novosibirsk, Russia
V. Blinov , Y.Skovpen , D. Shtol State Research Center of Russian Federation, Institute for High Energy Physics, Protvino,Russia
I. Azhgirey, I. Bayshev, S. Bitioukov, D. Elumakhov, V. Kachanov, A. Kalinin, D. Konstantinov,P. Mandrik, V. Petrov, R. Ryutin, A. Sobol, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov
University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade,Serbia
P. Adzic , P. Cirkovic, D. Devetak, M. Dordevic, J. Milosevic, V. Rekovic Centro de Investigaciones Energ´eticas Medioambientales y Tecnol ´ogicas (CIEMAT),Madrid, Spain
J. Alcaraz Maestre, M. Barrio Luna, M. Cerrada, N. Colino, B. De La Cruz, A. DelgadoPeris, A. Escalante Del Valle, C. Fernandez Bedoya, J.P. Fern´andez Ramos, J. Flix, M.C. Fouz,O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, D. Moran, A. P´erez-CaleroYzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, M.S. Soares,A. ´Alvarez Fern´andez
Universidad Aut ´onoma de Madrid, Madrid, Spain
J.F. de Troc ´oniz, M. Missiroli
Universidad de Oviedo, Oviedo, Spain
J. Cuevas, C. Erice, J. Fernandez Menendez, I. Gonzalez Caballero, J.R. Gonz´alez Fern´andez,E. Palencia Cortezon, S. Sanchez Cruz, P. Vischia, J.M. Vizan Garcia
Instituto de F´ısica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain
I.J. Cabrillo, A. Calderon, B. Chazin Quero, E. Curras, J. Duarte Campderros, M. Fernandez,J. Garcia-Ferrero, G. Gomez, A. Lopez Virto, J. Marco, C. Martinez Rivero, P. Martinez Ruiz delArbol, F. Matorras, J. Piedra Gomez, T. Rodrigo, A. Ruiz-Jimeno, L. Scodellaro, N. Trevisani,I. Vila, R. Vilar Cortabitarte
CERN, European Organization for Nuclear Research, Geneva, Switzerland
D. Abbaneo, B. Akgun, E. Auffray, P. Baillon, A.H. Ball, D. Barney, M. Bianco, P. Bloch,A. Bocci, C. Botta, T. Camporesi, R. Castello, M. Cepeda, G. Cerminara, E. Chapon, Y. Chen,D. d’Enterria, A. Dabrowski, V. Daponte, A. David, M. De Gruttola, A. De Roeck, N. Deelen,M. Dobson, T. du Pree, M. D ¨unser, N. Dupont, A. Elliott-Peisert, P. Everaerts, F. Fallavollita,G. Franzoni, J. Fulcher, W. Funk, D. Gigi, A. Gilbert, K. Gill, F. Glege, D. Gulhan, P. Harris,J. Hegeman, V. Innocente, A. Jafari, P. Janot, O. Karacheban , J. Kieseler, V. Kn ¨unz,A. Kornmayer, M.J. Kortelainen, M. Krammer , C. Lange, P. Lecoq, C. Lourenc¸o, M.T. Lucchini,L. Malgeri, M. Mannelli, A. Martelli, F. Meijers, J.A. Merlin, S. Mersi, E. Meschi, P. Milenovic ,F. Moortgat, M. Mulders, H. Neugebauer, J. Ngadiuba, S. Orfanelli, L. Orsini, L. Pape, E. Perez,M. Peruzzi, A. Petrilli, G. Petrucciani, A. Pfeiffer, M. Pierini, D. Rabady, A. Racz, T. Reis,G. Rolandi , M. Rovere, H. Sakulin, C. Sch¨afer, C. Schwick, M. Seidel, M. Selvaggi, A. Sharma,P. Silva, P. Sphicas , A. Stakia, J. Steggemann, M. Stoye, M. Tosi, D. Treille, A. Triossi, A. Tsirou,V. Veckalns , M. Verweij, W.D. Zeuner Paul Scherrer Institut, Villigen, Switzerland
W. Bertl † , L. Caminada , K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli,D. Kotlinski, U. Langenegger, T. Rohe, S.A. Wiederkehr Institute for Particle Physics, ETH Zurich, Zurich, Switzerland
M. Backhaus, L. B¨ani, P. Berger, L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Doneg`a, C. Dorfer, C. Grab, C. Heidegger, D. Hits, J. Hoss, G. Kasieczka, T. Klijnsma, W. Lustermann,B. Mangano, M. Marionneau, M.T. Meinhard, D. Meister, F. Micheli, P. Musella, F. Nessi-Tedaldi, F. Pandolfi, J. Pata, F. Pauss, G. Perrin, L. Perrozzi, M. Quittnat, M. Reichmann,D.A. Sanz Becerra, M. Sch ¨onenberger, L. Shchutska, V.R. Tavolaro, K. Theofilatos,M.L. Vesterbacka Olsson, R. Wallny, D.H. Zhu
Universit¨at Z ¨urich, Zurich, Switzerland
T.K. Aarrestad, C. Amsler , M.F. Canelli, A. De Cosa, R. Del Burgo, S. Donato, C. Galloni,T. Hreus, B. Kilminster, D. Pinna, G. Rauco, P. Robmann, D. Salerno, K. Schweiger, C. Seitz,Y. Takahashi, A. Zucchetta National Central University, Chung-Li, Taiwan
V. Candelise, T.H. Doan, Sh. Jain, R. Khurana, C.M. Kuo, W. Lin, A. Pozdnyakov, S.S. Yu
National Taiwan University (NTU), Taipei, Taiwan
Arun Kumar, P. Chang, Y. Chao, K.F. Chen, P.H. Chen, F. Fiori, W.-S. Hou, Y. Hsiung, Y.F. Liu,R.-S. Lu, E. Paganis, A. Psallidas, A. Steen, J.f. Tsai
Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand
B. Asavapibhop, K. Kovitanggoon, G. Singh, N. Srimanobhas
C¸ ukurova University, Physics Department, Science and Art Faculty, Adana, Turkey
F. Boran, S. Cerci , S. Damarseckin, Z.S. Demiroglu, C. Dozen, I. Dumanoglu, S. Girgis,G. Gokbulut, Y. Guler, I. Hos , E.E. Kangal , O. Kara, A. Kayis Topaksu, U. Kiminsu,M. Oglakci, G. Onengut , K. Ozdemir , D. Sunar Cerci , B. Tali , S. Turkcapar, I.S. Zorbakir,C. Zorbilmez Middle East Technical University, Physics Department, Ankara, Turkey
B. Bilin, G. Karapinar , K. Ocalan , M. Yalvac, M. Zeyrek Bogazici University, Istanbul, Turkey
E. G ¨ulmez, M. Kaya , O. Kaya , S. Tekten, E.A. Yetkin Istanbul Technical University, Istanbul, Turkey
M.N. Agaras, S. Atay, A. Cakir, K. Cankocak
Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov,Ukraine
B. Grynyov
National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine
L. Levchuk
University of Bristol, Bristol, United Kingdom
F. Ball, L. Beck, J.J. Brooke, D. Burns, E. Clement, D. Cussans, O. Davignon, H. Flacher,J. Goldstein, G.P. Heath, H.F. Heath, J. Jacob, L. Kreczko, D.M. Newbold , S. Paramesvaran,T. Sakuma, S. Seif El Nasr-storey, D. Smith, V.J. Smith Rutherford Appleton Laboratory, Didcot, United Kingdom
A. Belyaev , C. Brew, R.M. Brown, L. Calligaris, D. Cieri, D.J.A. Cockerill, J.A. Coughlan,K. Harder, S. Harper, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea, I.R. Tomalin,T. Williams Imperial College, London, United Kingdom
G. Auzinger, R. Bainbridge, J. Borg, S. Breeze, O. Buchmuller, A. Bundock, S. Casasso,M. Citron, D. Colling, L. Corpe, P. Dauncey, G. Davies, A. De Wit, M. Della Negra, R. Di Maria, A. Elwood, Y. Haddad, G. Hall, G. Iles, T. James, R. Lane, C. Laner, L. Lyons, A.-M. Magnan,S. Malik, L. Mastrolorenzo, T. Matsushita, J. Nash, A. Nikitenko , V. Palladino, M. Pesaresi,D.M. Raymond, A. Richards, A. Rose, E. Scott, C. Seez, A. Shtipliyski, S. Summers, A. Tapper,K. Uchida, M. Vazquez Acosta , T. Virdee , N. Wardle, D. Winterbottom, J. Wright, S.C. Zenz Brunel University, Uxbridge, United Kingdom
J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner,S. Zahid
Baylor University, Waco, USA
A. Borzou, K. Call, J. Dittmann, K. Hatakeyama, H. Liu, N. Pastika, C. Smith
Catholic University of America, Washington DC, USA
R. Bartek, A. Dominguez
The University of Alabama, Tuscaloosa, USA
A. Buccilli, S.I. Cooper, C. Henderson, P. Rumerio, C. West
Boston University, Boston, USA
D. Arcaro, A. Avetisyan, T. Bose, D. Gastler, D. Rankin, C. Richardson, J. Rohlf, L. Sulak, D. Zou
Brown University, Providence, USA
G. Benelli, D. Cutts, A. Garabedian, M. Hadley, J. Hakala, U. Heintz, J.M. Hogan, K.H.M. Kwok,E. Laird, G. Landsberg, J. Lee, Z. Mao, M. Narain, J. Pazzini, S. Piperov, S. Sagir, R. Syarif, D. Yu
University of California, Davis, Davis, USA
R. Band, C. Brainerd, D. Burns, M. Calderon De La Barca Sanchez, M. Chertok, J. Conway,R. Conway, P.T. Cox, R. Erbacher, C. Flores, G. Funk, M. Gardner, W. Ko, R. Lander, C. Mclean,M. Mulhearn, D. Pellett, J. Pilot, S. Shalhout, M. Shi, J. Smith, D. Stolp, K. Tos, M. Tripathi,Z. Wang
University of California, Los Angeles, USA
M. Bachtis, C. Bravo, R. Cousins, A. Dasgupta, A. Florent, J. Hauser, M. Ignatenko, N. Mccoll,S. Regnard, D. Saltzberg, C. Schnaible, V. Valuev
University of California, Riverside, Riverside, USA
E. Bouvier, K. Burt, R. Clare, J. Ellison, J.W. Gary, S.M.A. Ghiasi Shirazi, G. Hanson, J. Heilman,E. Kennedy, F. Lacroix, O.R. Long, M. Olmedo Negrete, M.I. Paneva, W. Si, L. Wang, H. Wei,S. Wimpenny, B. R. Yates
University of California, San Diego, La Jolla, USA
J.G. Branson, S. Cittolin, M. Derdzinski, R. Gerosa, D. Gilbert, B. Hashemi, A. Holzner, D. Klein,G. Kole, V. Krutelyov, J. Letts, I. Macneill, M. Masciovecchio, D. Olivito, S. Padhi, M. Pieri,M. Sani, V. Sharma, S. Simon, M. Tadel, A. Vartak, S. Wasserbaech , J. Wood, F. W ¨urthwein,A. Yagil, G. Zevi Della Porta University of California, Santa Barbara - Department of Physics, Santa Barbara, USA
N. Amin, R. Bhandari, J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta, M. FrancoSevilla, C. George, F. Golf, L. Gouskos, J. Gran, R. Heller, J. Incandela, S.D. Mullin,A. Ovcharova, H. Qu, J. Richman, D. Stuart, I. Suarez, J. Yoo
California Institute of Technology, Pasadena, USA
D. Anderson, J. Bendavid, A. Bornheim, J.M. Lawhorn, H.B. Newman, T. Nguyen, C. Pena,M. Spiropulu, J.R. Vlimant, S. Xie, Z. Zhang, R.Y. Zhu Carnegie Mellon University, Pittsburgh, USA
M.B. Andrews, T. Ferguson, T. Mudholkar, M. Paulini, J. Russ, M. Sun, H. Vogel, I. Vorobiev,M. Weinberg
University of Colorado Boulder, Boulder, USA
J.P. Cumalat, W.T. Ford, F. Jensen, A. Johnson, M. Krohn, S. Leontsinis, T. Mulholland,K. Stenson, S.R. Wagner
Cornell University, Ithaca, USA
J. Alexander, J. Chaves, J. Chu, S. Dittmer, K. Mcdermott, N. Mirman, J.R. Patterson, D. Quach,A. Rinkevicius, A. Ryd, L. Skinnari, L. Soffi, S.M. Tan, Z. Tao, J. Thom, J. Tucker, P. Wittich,M. Zientek
Fermi National Accelerator Laboratory, Batavia, USA
S. Abdullin, M. Albrow, M. Alyari, G. Apollinari, A. Apresyan, A. Apyan, S. Banerjee,L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, G. Bolla † , K. Burkett, J.N. Butler,A. Canepa, G.B. Cerati, H.W.K. Cheung, F. Chlebana, M. Cremonesi, J. Duarte, V.D. Elvira,J. Freeman, Z. Gecse, E. Gottschalk, L. Gray, D. Green, S. Gr ¨unendahl, O. Gutsche, R.M. Harris,S. Hasegawa, J. Hirschauer, Z. Hu, B. Jayatilaka, S. Jindariani, M. Johnson, U. Joshi, B. Klima,B. Kreis, S. Lammel, D. Lincoln, R. Lipton, M. Liu, T. Liu, R. Lopes De S´a, J. Lykken,K. Maeshima, N. Magini, J.M. Marraffino, D. Mason, P. McBride, P. Merkel, S. Mrenna, S. Nahn,V. O’Dell, K. Pedro, O. Prokofyev, G. Rakness, L. Ristori, B. Schneider, E. Sexton-Kennedy,A. Soha, W.J. Spalding, L. Spiegel, S. Stoynev, J. Strait, N. Strobbe, L. Taylor, S. Tkaczyk,N.V. Tran, L. Uplegger, E.W. Vaandering, C. Vernieri, M. Verzocchi, R. Vidal, M. Wang,H.A. Weber, A. Whitbeck University of Florida, Gainesville, USA
D. Acosta, P. Avery, P. Bortignon, D. Bourilkov, A. Brinkerhoff, A. Carnes, M. Carver, D. Curry,R.D. Field, I.K. Furic, S.V. Gleyzer, B.M. Joshi, J. Konigsberg, A. Korytov, K. Kotov, P. Ma,K. Matchev, H. Mei, G. Mitselmakher, D. Rank, K. Shi, D. Sperka, N. Terentyev, L. Thomas,J. Wang, S. Wang, J. Yelton
Florida International University, Miami, USA
Y.R. Joshi, S. Linn, P. Markowitz, J.L. Rodriguez
Florida State University, Tallahassee, USA
A. Ackert, T. Adams, A. Askew, S. Hagopian, V. Hagopian, K.F. Johnson, T. Kolberg,G. Martinez, T. Perry, H. Prosper, A. Saha, A. Santra, V. Sharma, R. Yohay
Florida Institute of Technology, Melbourne, USA
M.M. Baarmand, V. Bhopatkar, S. Colafranceschi, M. Hohlmann, D. Noonan, T. Roy,F. Yumiceva
University of Illinois at Chicago (UIC), Chicago, USA
M.R. Adams, L. Apanasevich, D. Berry, R.R. Betts, R. Cavanaugh, X. Chen, O. Evdokimov,C.E. Gerber, D.A. Hangal, D.J. Hofman, K. Jung, J. Kamin, I.D. Sandoval Gonzalez, M.B. Tonjes,H. Trauger, N. Varelas, H. Wang, Z. Wu, J. Zhang
The University of Iowa, Iowa City, USA
B. Bilki , W. Clarida, K. Dilsiz , S. Durgut, R.P. Gandrajula, M. Haytmyradov, V. Khristenko,J.-P. Merlo, H. Mermerkaya , A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul , Y. Onel,F. Ozok , A. Penzo, C. Snyder, E. Tiras, J. Wetzel, K. Yi Johns Hopkins University, Baltimore, USA
B. Blumenfeld, A. Cocoros, N. Eminizer, D. Fehling, L. Feng, A.V. Gritsan, P. Maksimovic,J. Roskes, U. Sarica, M. Swartz, M. Xiao, C. You
The University of Kansas, Lawrence, USA
A. Al-bataineh, P. Baringer, A. Bean, S. Boren, J. Bowen, J. Castle, S. Khalil, A. Kropivnitskaya,D. Majumder, W. Mcbrayer, M. Murray, C. Royon, S. Sanders, E. Schmitz, J.D. Tapia Takaki,Q. Wang
Kansas State University, Manhattan, USA
A. Ivanov, K. Kaadze, Y. Maravin, A. Mohammadi, L.K. Saini, N. Skhirtladze, S. Toda
Lawrence Livermore National Laboratory, Livermore, USA
F. Rebassoo, D. Wright
University of Maryland, College Park, USA
C. Anelli, A. Baden, O. Baron, A. Belloni, B. Calvert, S.C. Eno, Y. Feng, C. Ferraioli, N.J. Hadley,S. Jabeen, G.Y. Jeng, R.G. Kellogg, J. Kunkle, A.C. Mignerey, F. Ricci-Tam, Y.H. Shin, A. Skuja,S.C. Tonwar
Massachusetts Institute of Technology, Cambridge, USA
D. Abercrombie, B. Allen, V. Azzolini, R. Barbieri, A. Baty, R. Bi, S. Brandt, W. Busza, I.A. Cali,M. D’Alfonso, Z. Demiragli, G. Gomez Ceballos, M. Goncharov, D. Hsu, M. Hu, Y. Iiyama,G.M. Innocenti, M. Klute, D. Kovalskyi, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, B. Maier,A.C. Marini, C. Mcginn, C. Mironov, S. Narayanan, X. Niu, C. Paus, C. Roland, G. Roland,J. Salfeld-Nebgen, G.S.F. Stephans, K. Tatar, D. Velicanu, J. Wang, T.W. Wang, B. Wyslouch
University of Minnesota, Minneapolis, USA
A.C. Benvenuti, R.M. Chatterjee, A. Evans, P. Hansen, J. Hiltbrand, S. Kalafut, Y. Kubota,Z. Lesko, J. Mans, S. Nourbakhsh, N. Ruckstuhl, R. Rusack, J. Turkewitz, M.A. Wadud
University of Mississippi, Oxford, USA
J.G. Acosta, S. Oliveros
University of Nebraska-Lincoln, Lincoln, USA
E. Avdeeva, K. Bloom, D.R. Claes, C. Fangmeier, R. Gonzalez Suarez, R. Kamalieddin,I. Kravchenko, J. Monroy, J.E. Siado, G.R. Snow, B. Stieger
State University of New York at Buffalo, Buffalo, USA
J. Dolen, A. Godshalk, C. Harrington, I. Iashvili, D. Nguyen, A. Parker, S. Rappoccio,B. Roozbahani
Northeastern University, Boston, USA
G. Alverson, E. Barberis, A. Hortiangtham, A. Massironi, D.M. Morse, T. Orimoto, R. TeixeiraDe Lima, D. Trocino, D. Wood
Northwestern University, Evanston, USA
S. Bhattacharya, O. Charaf, K.A. Hahn, N. Mucia, N. Odell, B. Pollack, M.H. Schmitt, K. Sung,M. Trovato, M. Velasco
University of Notre Dame, Notre Dame, USA
N. Dev, M. Hildreth, K. Hurtado Anampa, C. Jessop, D.J. Karmgard, N. Kellams, K. Lannon,N. Loukas, N. Marinelli, F. Meng, C. Mueller, Y. Musienko , M. Planer, A. Reinsvold, R. Ruchti,G. Smith, S. Taroni, M. Wayne, M. Wolf, A. Woodard The Ohio State University, Columbus, USA
J. Alimena, L. Antonelli, B. Bylsma, L.S. Durkin, S. Flowers, B. Francis, A. Hart, C. Hill, W. Ji,B. Liu, W. Luo, D. Puigh, B.L. Winer, H.W. Wulsin
Princeton University, Princeton, USA
S. Cooperstein, O. Driga, P. Elmer, J. Hardenbrook, P. Hebda, S. Higginbotham, D. Lange, J. Luo,D. Marlow, K. Mei, I. Ojalvo, J. Olsen, C. Palmer, P. Pirou´e, D. Stickland, C. Tully
University of Puerto Rico, Mayaguez, USA
S. Malik, S. Norberg
Purdue University, West Lafayette, USA
A. Barker, V.E. Barnes, S. Das, S. Folgueras, L. Gutay, M.K. Jha, M. Jones, A.W. Jung,A. Khatiwada, D.H. Miller, N. Neumeister, C.C. Peng, H. Qiu, J.F. Schulte, J. Sun, F. Wang,W. Xie
Purdue University Northwest, Hammond, USA
T. Cheng, N. Parashar, J. Stupak
Rice University, Houston, USA
A. Adair, Z. Chen, K.M. Ecklund, S. Freed, F.J.M. Geurts, M. Guilbaud, M. Kilpatrick, W. Li,B. Michlin, M. Northup, B.P. Padley, J. Roberts, J. Rorie, W. Shi, Z. Tu, J. Zabel, A. Zhang
University of Rochester, Rochester, USA
A. Bodek, P. de Barbaro, R. Demina, Y.t. Duh, T. Ferbel, M. Galanti, A. Garcia-Bellido, J. Han,O. Hindrichs, A. Khukhunaishvili, K.H. Lo, P. Tan, M. Verzetti
The Rockefeller University, New York, USA
R. Ciesielski, K. Goulianos, C. Mesropian
Rutgers, The State University of New Jersey, Piscataway, USA
A. Agapitos, J.P. Chou, Y. Gershtein, T.A. G ´omez Espinosa, E. Halkiadakis, M. Heindl,E. Hughes, S. Kaplan, R. Kunnawalkam Elayavalli, S. Kyriacou, A. Lath, R. Montalvo, K. Nash,M. Osherson, H. Saka, S. Salur, S. Schnetzer, D. Sheffield, S. Somalwar, R. Stone, S. Thomas,P. Thomassen, M. Walker
University of Tennessee, Knoxville, USA
A.G. Delannoy, M. Foerster, J. Heideman, G. Riley, K. Rose, S. Spanier, K. Thapa
Texas A&M University, College Station, USA
O. Bouhali , A. Castaneda Hernandez , A. Celik, M. Dalchenko, M. De Mattia, A. Delgado,S. Dildick, R. Eusebi, J. Gilmore, T. Huang, T. Kamon , R. Mueller, Y. Pakhotin, R. Patel,A. Perloff, L. Perni`e, D. Rathjens, A. Safonov, A. Tatarinov, K.A. Ulmer Texas Tech University, Lubbock, USA
N. Akchurin, J. Damgov, F. De Guio, P.R. Dudero, J. Faulkner, E. Gurpinar, S. Kunori,K. Lamichhane, S.W. Lee, T. Libeiro, T. Mengke, S. Muthumuni, T. Peltola, S. Undleeb,I. Volobouev, Z. Wang
Vanderbilt University, Nashville, USA
S. Greene, A. Gurrola, R. Janjam, W. Johns, C. Maguire, A. Melo, H. Ni, K. Padeken, P. Sheldon,S. Tuo, J. Velkovska, Q. Xu
University of Virginia, Charlottesville, USA
M.W. Arenton, P. Barria, B. Cox, R. Hirosky, M. Joyce, A. Ledovskoy, H. Li, C. Neu,T. Sinthuprasith, Y. Wang, E. Wolfe, F. Xia Wayne State University, Detroit, USA
R. Harr, P.E. Karchin, N. Poudyal, J. Sturdy, P. Thapa, S. Zaleski
University of Wisconsin - Madison, Madison, WI, USA
M. Brodski, J. Buchanan, C. Caillol, S. Dasu, L. Dodd, S. Duric, B. Gomber, M. Grothe,M. Herndon, A. Herv´e, U. Hussain, P. Klabbers, A. Lanaro, A. Levine, K. Long, R. Loveless,G. Polese, T. Ruggles, A. Savin, N. Smith, W.H. Smith, D. Taylor, N. Woods † : Deceased1: Also at Vienna University of Technology, Vienna, Austria2: Also at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing,China3: Also at IRFU, CEA, Universit´e Paris-Saclay, Gif-sur-Yvette, France4: Also at Universidade Estadual de Campinas, Campinas, Brazil5: Also at Universidade Federal de Pelotas, Pelotas, Brazil6: Also at Universit´e Libre de Bruxelles, Bruxelles, Belgium7: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia8: Also at Joint Institute for Nuclear Research, Dubna, Russia9: Also at Suez University, Suez, Egypt10: Now at British University in Egypt, Cairo, Egypt11: Now at Helwan University, Cairo, Egypt12: Also at Universit´e de Haute Alsace, Mulhouse, France13: Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University,Moscow, Russia14: Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland15: Also at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany16: Also at University of Hamburg, Hamburg, Germany17: Also at Brandenburg University of Technology, Cottbus, Germany18: Also at MTA-ELTE Lend ¨ulet CMS Particle and Nuclear Physics Group, E ¨otv ¨os Lor´andUniversity, Budapest, Hungary19: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary20: Also at Institute of Physics, University of Debrecen, Debrecen, Hungary21: Also at Indian Institute of Technology Bhubaneswar, Bhubaneswar, India22: Also at Institute of Physics, Bhubaneswar, India23: Also at University of Visva-Bharati, Santiniketan, India24: Also at University of Ruhuna, Matara, Sri Lanka25: Also at Isfahan University of Technology, Isfahan, Iran26: Also at Yazd University, Yazd, Iran27: Also at Plasma Physics Research Center, Science and Research Branch, Islamic AzadUniversity, Tehran, Iran28: Also at Universit`a degli Studi di Siena, Siena, Italy29: Also at INFN Sezione di Milano-Bicocca; Universit`a di Milano-Bicocca, Milano, Italy30: Also at Laboratori Nazionali di Legnaro dell’INFN, Legnaro, Italy31: Also at Purdue University, West Lafayette, USA32: Also at International Islamic University of Malaysia, Kuala Lumpur, Malaysia33: Also at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia34: Also at Consejo Nacional de Ciencia y Tecnolog´ıa, Mexico city, Mexico35: Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland36: Also at Institute for Nuclear Research, Moscow, Russia37: Now at National Research Nuclear University ’Moscow Engineering Physics8