First measurement of quarkonium polarization in nuclear collisions at the LHC
EEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
CERN-EP-2020-09221 May 2020c (cid:13)
First measurement of quarkonium polarizationin nuclear collisions at the LHC
ALICE Collaboration ∗ Abstract
The polarization of inclusive J/ ψ and ϒ ( ) produced in Pb–Pb collisions at √ s NN = .
02 TeVat the LHC is measured with the ALICE detector. The study is carried out by reconstructing thequarkonium through its decay to muon pairs in the rapidity region 2 . < y < λ θ , λ φ and λ θφ are measured in the helicity and Collins-Soper reference frames, in the transverse momentuminterval 2 < p T <
10 GeV/ c and p T <
15 GeV/ c for the J/ ψ and ϒ ( ) , respectively. The polarizationparameters for the J/ ψ are found to be compatible with zero, with a maximum deviation at low p T ofabout 2 σ , for both reference frames and over the whole p T range. The values are compared with thecorresponding results obtained for pp collisions at √ s = ϒ ( ) production in Pb–Pb collisions are also consistent with zero. ∗ See Appendix A for the list of collaboration members a r X i v : . [ nu c l - e x ] M a y uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration Quarkonia, bound states of charm (c) and anticharm (c) or bottom (b) and antibottom (b) quarks, repre-sent an important tool to test our understanding of quantum chromodynamics (QCD), since their produc-tion process involves both perturbative and non-perturbative aspects. At high energy, the creation of theheavy quark-antiquark pair is a process that can be described using a perturbative QCD approach, due tothe large value of the charm and bottom quark masses ( m c ∼ . c , m b ∼ . c ). However,the subsequent formation of the bound state is a non-perturbative process that can be described only byempirical models or effective field theory approaches. Among those, models based on Non-RelativisticQCD (NRQCD) [1] give the most successful description of the production cross section, as measuredat high-energy hadron colliders (Tevatron, RHIC, LHC) [2–13]. In this approach, the non-perturbativeaspects are parameterized via long-distance matrix elements (LDME), corresponding to the possible in-termediate color, spin and angular momentum states of the evolving quark-antiquark pair. The values ofLDMEs need to be fitted on a chosen sample of measurements and can be then considered as universalquantities, in the sense that they can be used in the calculation of production cross sections and otherobservables corresponding, for example, to different collision systems and energies.Among the various charmonium states, the J/ ψ meson, with quantum numbers J PC = −− , was thefirst to be discovered. It is surely the most studied, also due to the sizeable decay branching ratio todilepton pairs ((5 . ± . µ + µ − channel [14]) that represents an excellent experimentalsignature. While the J/ ψ production cross sections are well reproduced by NRQCD-based models, itwas soon realized that describing the measured polarization of this state represents a much more difficultproblem [15]. The polarization, corresponding to the orientation of the particle spin with respect to achosen axis, can be accessed via a study of the polar ( θ ) and azimuthal ( φ ) production angles, relativeto that axis, of the two-body decay products in the quarkonium rest frame. Their angular distribution W ( θ , φ ) is parameterized as W ( θ , φ ) ∝ + λ θ (cid:0) + λ θ cos θ + λ φ sin θ cos 2 φ + λ θφ sin 2 θ cos φ (cid:1) , (1)with the polarization parameters λ θ , λ φ and λ θφ corresponding to various combinations of the elementsof the spin density matrix of J/ ψ production [16]. In particular, the two cases ( λ θ = λ φ = λ θφ = λ θ = − λ φ = λ θφ =
0) correspond to the so-called transverse and longitudinal polarizations,respectively. At leading order, the high- p T production is dominated by gluon fragmentation and there-fore the J/ ψ would be expected to be transversely polarized [15]. However, the results from the CDFexperiment at Tevatron showed that the J/ ψ exhibits a very small polarization [17, 18], an observationwhich was impossible to reconcile with the NRQCD prediction. As of today, on the experimental side,accurate results on inclusive and prompt (i.e., removing contributions from b-quark decays) J/ ψ polar-ization have become available at LHC energies [19–22]. They confirm that this state shows little or nopolarization in a wide rapidity (up to y = .
5) and transverse momentum region (from 2 to 70 GeV/ c ),with the exception of the LHCb measurements at √ s = λ θ = − . ± . < p T <
15 GeV/ c and 2 < y < .
5, in the helicity frame (its definition willbe given later in Sec. 3). On the theory side, a huge effort was pursued in order to move to a completenext-to-leading order (NLO) description of the J/ ψ production process [23, 24], and to the calculationof the polarization variables [25, 26]. Further important progress includes a quantitative evaluation ofthe contribution of feed-down processes (J/ ψ coming from the decay of χ c and ψ ( ) states) on thepolarization observables [27]. It was shown that at NLO there are rather large cancellations betweencontributions corresponding to the different possible combinations of the spin and angular momentumof the intermediate cc states, reaching a more satisfactory description of the absence of polarization ob-served in the data [28]. However, those descriptions usually require the inclusion of both cross section2uarkonium polarization in nuclear collisions at the LHC ALICE Collaborationand polarization results in the fit of the LDME, leading to a more limited predictive power on the po-larization observables and to large variations in the values of the extracted LDME values, depending onthe set of data used for their determination. Finally, the description of the J/ ψ production in the NRQCDframework was recently extended to the low- p T region, and the polarization parameters were studiedin a color glass condensate (CGC) + NRQCD formalism, obtaining a fair agreement with LHC data atforward rapidity [29]. Measurements of the polarization parameters are also available for several bot-tomonium states, and in particular for the ϒ ( ) , ϒ ( ) and ϒ ( ) resonances, which were shown toexhibit little or no polarization at LHC energies [30, 31]. Approaches similar to that adopted for char-monium, which also need to take into account the rather complex feed-down decay structure for thesestates, lead to a fair agreement with the experimental results [32].In this Letter, we move a step forward by presenting the first measurement of J/ ψ and ϒ ( ) polar-ization in ultrarelativistic heavy-ion interactions performed by the ALICE Collaboration by studyingPb–Pb collisions at √ s NN = .
02 TeV. Such collisions represent an important source of information forthe investigation of the phase diagram of QCD [33], and in particular for the study of the propertiesof the quark–gluon plasma (QGP), a state of matter where quarks and gluons are not confined insidehadrons [34]. Among the experimental observables studied in heavy-ion collisions the suppression ofheavy quarkonium production is a fundamental signal, since QGP formation prevents the binding of theheavy-quark pair due to the screening of the color charge [35] and, more generally, has strong effects onthe spectral functions [36]. At LHC energies, another mechanism, corresponding to the (re)generationof charmonium states in the QGP and/or when the system hadronizes, becomes relevant [37, 38], in par-ticular at low p T , due to the large charm-quark multiplicity ( >
100 pairs in a central Pb–Pb collision).The presence of a deconfined system may in principle affect also the polarization of quarkonium states.In Ref. [39] the observation of a partial transverse polarization for the J/ ψ was predicted in case of QGPformation, due to a modification of the non-perturbative effects in the high energy-density phase. Moregenerally, the observed prompt J/ ψ are known to be a mixture of direct production and decay productsfrom higher-mass charmonium states ( ψ ( ) , χ c ). In nuclear collisions, since suppression effects areexpected to affect more strongly the less bound states, the relative contribution of direct and feed-downproduction would change with respect to that in pp collisions, and the overall measured polarization maybe different according to the potentially different polarization of the various states [40, 41]. On the otherhand, the contribution of the regeneration mechanism in the J/ ψ formation process by recombinationof uncorrelated cc pairs is likely to give rise to unpolarized production at low p T . Finally, the possiblepresence of polarization is known to strongly affect the acceptance for J/ ψ detection in the dilepton de-cay (up to 20–30% [19]), and its measurement is an important requisite for an unbiased evaluation ofthe absolute yields in nuclear collisions. A first measurement of ϒ ( ) polarization in Pb–Pb collisionsis also presented in this Letter, even if the corresponding candidate sample is smaller by a factor ∼ ψ should hold, except that the contribution of the regeneration mechanism should be negligible due to themuch lower multiplicity of bottom quarks with respect to charm.The next sections of the Letter are organized as follows. Section 2 contains a short description of theexperimental apparatus and some details on the data sample used in this analysis. The analysis procedureand the evaluation of systematic uncertainties are presented in Sec. 3, while the results on the J/ ψ and ϒ ( ) polarization parameters λ θ , λ φ and λ θφ are shown in Sec. 4. The conclusions are presented inSec. 5. The measurement described in this Letter is performed with the ALICE detector [42, 43], whose maincomponents are a central barrel and a forward muon spectrometer. The latter covers the pseudorapidityregion − < η < − . × m field integral. Downstream of the tracking system, an iron wall filters outthe remaining hadrons as well as low-momentum muons originating from pion and kaon decays, and isfollowed by two trigger stations (resistive plate chambers). Another forward detector, the V0 [45], com-posed of two scintillator arrays located at opposite sides of the interaction point (IP) and covering thepseudorapidity intervals − . < η < − . . < η < .
1, provides the minimum bias (MB) triggerwhich is given by a coincidence of signals from the two sides. Among the central barrel detectors, thetwo layers of the Silicon Pixel Detector (SPD), with | η | < | η | < . ± p µ T = c , corre-sponding to the value for which the single-muon trigger efficiency reaches 50% [48]. The single-muontrigger efficiency reaches a plateau value of 98% at ∼ . c .The events are further characterized according to their centrality, i.e., the degree of geometric overlapof the colliding nuclei. It is estimated by means of a Glauber model fit to the V0 signal amplitudedistribution [49, 50], with more central events leading to a larger signal in the V0. In this analysis, eventscorresponding to the most central 90% of the inelastic Pb–Pb cross section are selected.The results of the analysis are obtained using the √ s NN = 5.02 TeV Pb–Pb data samples collected bythe ALICE experiment during the years 2015 and 2018, corresponding to an integrated luminosity L int ∼ µ b − . The J/ ψ and ϒ ( ) candidates are formed by combining opposite-sign muons reconstructed using thetracking algorithm described in Ref. [44]. In order to reject tracks at the edge of the spectrometer ac-ceptance, the condition − < η µ < − . . < R abs < . ψ polarization parameters λ θ , λ φ and λ θφ are studied as a function of transverse momentum in theintervals 2 < p T <
4, 4 < p T < < p T <
10 GeV/ c . For each p T interval, a two–dimensional (2D)grid of dimuon invariant-mass spectra is created, corresponding to intervals in cos θ and φ , where θ and φ are the polar and azimuthal emission angles, respectively, of the decay products in the J/ ψ rest frame, withrespect to the reference axis. More in detail, the 2D grid covers the fiducial region − . < cos θ < . . < φ < π − . φ = π ), withthe choice of the boundaries as well as the width of the intervals dictated by acceptance considerations.The analysis is performed choosing two different reference systems for the determination of the angularvariables. In the Collins-Soper (CS) frame the z -axis is defined as the bisector of the angle between thedirection of one beam and the opposite of the direction of the other one in the rest frame of the decayingparticle, allowing therefore an evaluation of the polarization parameters with respect to the direction ofmotion of the colliding hadrons. In the helicity (HE) reference frame the z -axis is given by the direction4uarkonium polarization in nuclear collisions at the LHC ALICE Collaborationof the decaying particle in the center-of-mass frame of the collision, and therefore the polarization can beevaluated with respect to the momentum direction of the J/ ψ itself. The φ = ψ rest frame.For each dimuon invariant-mass spectrum, the J/ ψ raw yield is obtained by means of a fit in the interval2 . < m µµ < . c . The background continuum is parameterized with a Gaussian distributionwhose width varies linearly with the mass or, alternatively, with a fourth degree polynomial functiontimes an exponential. The J/ ψ signal is modeled with a pseudo-Gaussian function or with a Crystal Ballfunction with asymmetric tails on both sides of the peak [51].The J/ ψ mass is kept free in the fits, while for each interval ( i , j ) in (cos θ , φ ) the width is fixed to σ i , j J / ψ = σ i , j , MCJ / ψ · ( σ J / ψ / σ MCJ / ψ ) , i.e., scaling the resonance width extracted from Monte Carlo (MC) simulations( σ i , j , MCJ / ψ ) by the ratio between the width obtained by fitting the angle-integrated spectrum in data ( σ J / ψ )and MC ( σ MCJ / ψ ) for the p T interval under consideration. The parameters of the non-Gaussian tails of theresonance are kept fixed to the MC values. The ψ ( ) contribution, although comparatively negligible,is also taken into account in the fits, with its width and mass fixed in each fit to those of the J/ ψ accordingto the relations σ ψ ( ) = σ J / ψ · σ MC ψ ( ) / σ MCJ / ψ and m ψ ( ) = m J / ψ + m PDG ψ ( ) − m PDGJ / ψ , with the PDG massestaken from Ref. [14]. In Fig. 1 (left) an example of a fit to the invariant-mass spectrum in the J/ ψ massregion is shown. - m + m fi y ALICE, Inclusive J/ = 5.02 TeV, 0 - 90% NN s Pb - Pb < 4 , Helicity y , 2.5 < c < 4 GeV/ T p q -0.5 < cos < 1.57 rad f DataTotal fitBackground fit y J/(2S) y c C oun t s pe r M e V / ) c (GeV/ mm m - m + m fi (1S) ¡ ALICE, Inclusive = 5.02 TeV, 0 - 90% NN s Pb - Pb < 4, Helicity y , 2.5 < c < 15 GeV/ T p | < 0.1 q |cos DataTotal fitBackground fit(1S) ¡ (2S) ¡ c C oun t s pe r M e V / ) c (GeV/ mm m Figure 1:
Examples of fits to the raw invariant-mass distributions in the helicity reference frame. The left plot cor-responds to the J/ ψ mass region, while on the right a fit to the ϒ ( S ) mass region is shown. The fits are performedusing an extended Crystal Ball function for the resonance signals, while the background is parameterized with avariable width Gaussian. The width of the band around the total fit represents its uncertainty. The J/ ψ raw yields as a function of the angular variables are then corrected by the product of the ac-ceptance and detector efficiency ( A × ε ), which is evaluated via MC simulations. The J/ ψ are generatedaccording to p T and y distributions directly tuned on data [52] via an iterative procedure, and their decaymuons are propagated inside a realistic description of the ALICE setup, based on GEANT 3.21 [53]. Themisalignment of the detection elements and the time-dependent status of each electronic channel duringthe data taking period are taken into account as well. In the J/ ψ generation an isotropic distribution ofdecay products, corresponding to the assumption of no polarization, is adopted. In any case, due to the2D-correction procedure used and to the choice of relatively small (cos θ , φ ) intervals, the results arequite insensitive to the specific angular distribution assumed in the generation.5uarkonium polarization in nuclear collisions at the LHC ALICE CollaborationThe three polarization parameters λ θ , λ φ and λ θφ are obtained through fits of the 2D acceptance-corrected J/ ψ distributions according to Eq. 1. For each combination of signal and background shapeused in the fit to the dimuon invariant-mass spectra, a separate evaluation of the polarization parametersis carried out and their average is taken as the best estimate. The statistical uncertainty is given by theaverage of the statistical uncertainties of the 2D fits, while the root mean square of the results providesthe systematic uncertainty on the signal extraction, with the absolute values ranging between 0.002 and0.039. The 2D fits on the (cos θ , φ ) distributions only allow a determination of the absolute value of λ θφ , due to the presence of sin 2 θ in the corresponding term that induces an ambiguity in its sign. It ischecked that the values of λ θ and λ φ are stable against the choice of the sign of the λ θφ term. In thefollowing the λ θφ values corresponding to the choice of a positive sign are quoted. Figure 2 illustratesan example of the fit to the angular distributions. For better visibility, both the distribution and the fittedfunction are projected along one dimension. - - - - - q cos · q d c o s N d = 5.02 TeV NN s ALICE, Pb-Pb - m + m fi y Inclusive J/ < 4 , Helicity y , 2.5 < c < 6 GeV/ T p (rad) f · ) - (r ad f d N d = 5.02 TeV NN s ALICE, Pb-Pb - m + m fi y Inclusive J/ < 4 , Helicity y , 2.5 < c < 6 GeV/ T p Figure 2:
Fit to the J/ ψ
2D angular distributions in the helicity reference frame projected along cos θ (left) and φ (right) for 2 . < y < < p T < c . The displayed uncertainties are statistical. In addition to the systematic uncertainty related to the choice of the mass shapes for signal and back-ground, several other sources are taken into account. First, an alternative procedure for extracting the J/ ψ signal is carried out, by keeping its width as a free parameter in the invariant-mass fits. The correspond-ing results for the polarization parameters are then obtained and the averages of the values correspondingto fixing the width or not are taken as the central values for λ θ , λ φ and λ θφ . Half the difference betweenthe results obtained with free or MC-anchored widths is then considered as a further systematic uncer-tainty related to the signal extraction. This uncertainty is found to be the leading contribution to the totalabsolute systematic uncertainty on the polarization parameters, and ranges between 0.001 and 0.063, thelatter value corresponding to the uncertainty on λ HE θ for 2 < p T < c .Another source of systematic uncertainty is related to the evaluation of the trigger efficiency. The muontrigger response function as a function of the single muon transverse momentum p µ T can be obtainedvia MC or with a procedure based on data [54]. Small deviations are found for p µ T < c whichinduce an effect on A × ε for the J/ ψ . Therefore, the polarization parameters are re-calculated with A × ε values weighted in such a way to account for the deviations. The variation of the polarization parametersbetween the different trigger efficiency estimates is taken as the related systematic uncertainty, withvalues ranging from 0.001 to 0.043, the highest values being found for λ HE θ in 2 < p T <
4. The systematicuncertainty related to the evaluation of the muon tracking efficiency is found to be negligible for thisanalysis, allowing a significant reduction of the total systematic uncertainty with respect to previous ppanalyses [20]. Indeed, the difference between efficiencies calculated via MC or from data [54] is of theorder of 2%, but a detailed investigation has shown no dependence on the angular variables and therefore6uarkonium polarization in nuclear collisions at the LHC ALICE Collaborationno effect on the polarization parameters.Finally, the systematic uncertainty induced by the choice of the p T and y distributions used as an input forthe calculation of A × ε is evaluated testing alternative p T and y parameterizations, which are obtainedby varying within uncertainties the default distributions directly tuned on Pb–Pb data. The polarizationparameters extracted with the modified values of A × ε are compared with those obtained with the defaultinput shapes and the corresponding systematic uncertainty extracted in this way is found to range between0.001 and 0.030, with the largest value assigned to λ HE θ for 2 < p T < c . The influence of the choiceof the angular distributions of the J/ ψ decay products for the A × ε calculation is also investigated bymeans of an iterative procedure on these input distributions. The effect is found to be negligible, also dueto the fact that the 2D correction procedure on the angular variables is by definition relatively insensitiveto the specific choice of the corresponding distributions. A summary of the values of all the absolutesystematic uncertainties, which are considered as uncorrelated as a function of p T , is reported in Table 1.The total systematic uncertainties are obtained, for each parameter and p T interval, as the quadratic sumof the values. Table 1:
Summary of the absolute systematic uncertainties on the evaluation of the J/ ψ polarization parameters.All the uncertainties are considered as uncorrelated as a function of p T . Helicity Collins-Soper p T (GeV/ c ) Signal Width Trigger Input MC Signal Width Trigger Input MC λ θ < p T < < p T < < p T <
10 0.039 0.005 0.018 0.017 0.022 0.001 0.011 0.006 λ φ < p T < < p T < < p T <
10 0.002 0.009 0.001 0.002 0.005 0.013 0.011 0.002 λ θφ < p T < < p T < < p T <
10 0.020 0.019 0.007 0.008 0.007 0.042 0.003 0.013A similar procedure is followed for the extraction of the ϒ ( ) polarization parameters. Due to thesmaller candidate sample, integrated values over the kinematic interval 2 . < y < p T <
15 GeV/ c are obtained. The main difference with respect to the 2D approach followed for the J/ ψ is the use ofa simultaneous fit to the 1D angular distributions [20], after integration over the other variables. Forcompatibility with previous analyses, the requirement p µ T > c , which helps reducing the combi-natorial background, is included [55]. The ϒ ( ) signal extraction in the various cos θ and φ intervals isperformed by means of invariant-mass fits (see the right panel of Fig. 1 for an example). The functionschosen for the resonances are the same as in the J/ ψ analysis (pseudo-Gaussian or Crystal Ball), the massvalue is fixed to that obtained from a fit to the integrated invariant-mass distribution, while the width foreach angular interval is fixed to the MC value scaled by the ratio of the widths between data and MC forthe angle-integrated distributions. The tail parameters are fixed to MC values. The small contributionfrom ϒ ( ) is also included in the fits [55]. The systematic uncertainty on the signal extraction is calcu-lated with the same procedure adopted for the J/ ψ . No additional uncertainty related to signal widths isassigned, since the use of MC-based values for the resonance widths is mandatory given the low numberof counts. The uncertainty on the trigger efficiency is negligible, due to the additional requirement onthe single-muon transverse momentum which selects a p T -region where the trigger efficiency is veryhigh and its evaluation via data and MC is consistent. Finally, the procedure for the determination of theuncertainty related to the ϒ ( ) kinematic distributions used in the MC is the same as for the J/ ψ . Thetotal systematic uncertainties for the ϒ ( ) analysis are reported in Table 3, together with the results.7uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration The polarization parameters for J/ ψ inclusive production in Pb–Pb collisions at √ s NN = λ θ , λ φ and λ θφ are also compared with the LHCb [21] and ALICE [20]measurements in pp collisions at √ s = Table 2: J/ ψ polarization parameters, measured for Pb–Pb collisions at √ s NN = .
02 TeV, in the helicity andCollins-Soper reference frames in the rapidity interval 2 . < y <
4. The first uncertainty is statistical and thesecond systematic. p T (GeV/ c ) Helicity Collins-Soper λ θ < p T < . ± . ± . − . ± . ± . < p T < . ± . ± . − . ± . ± . < p T < − . ± . ± . − . ± . ± . λ φ < p T < − . ± . ± .
031 0 . ± . ± . < p T < − . ± . ± .
036 0 . ± . ± . < p T <
10 0 . ± . ± .
010 0 . ± . ± . λ θφ < p T < − . ± . ± . − . ± . ± . < p T < − . ± . ± . − . ± . ± . < p T < − . ± . ± .
030 0 . ± . ± . p T intervals and in both reference frames the values of the polarization parameters exhibit atmost slight deviations from zero. In particular, λ HE θ indicates a slight transverse polarization at low p T ( ∼ . σ effect), while λ CS θ shows a weak longitudinal polarization ( ∼ . σ ). When increasing p T , thecentral values of λ θ become close to zero. All values of λ φ and λ θφ are, in absolute value, smaller than0.1, except for λ HE θφ , which is − .
124 at low p T and deviates from zero by ∼ . σ .When comparing with the pp results, no significant difference is found with respect to ALICE resultsat √ s = √ s = p T in the helicity reference frame,where pp data [21] indicate a small but significant degree of longitudinal polarization, while the Pb–Pbresults favor a slightly transverse polarization. In Pb–Pb collisions at LHC energies, a significant fractionof the detected J/ ψ originates from the recombination of cc pairs in the QGP phase or when the systemhadronizes. The observed hint for a different polarization in pp and Pb–Pb might be a reflection ofthe different production mechanisms in the two systems, but more precise data, along with quantitativetheory estimates, are needed for a definite conclusion. It should also be noted that the ALICE resultsrefer to inclusive production, while LHCb has measured prompt J/ ψ . However, as discussed in Ref. [19],the size of the non-prompt component is small in the covered p T region (of the order of 15% at high p T ) and its polarization was also measured to be small by CDF ( λ HE θ ∼ − . ψ polarization should be negligible.In Table 3 the values of the ϒ ( ) polarization parameters are shown. The λ θ values are consistent withzero, with large uncertainties that prevent a firm conclusion on the absence of a significant polarizationin nuclear collisions. The λ φ and λ θφ values are also consistent with zero. The relatively smaller uncer-tainties for these parameters are related to a more uniform acceptance distribution as a function of theazimuthal angular variable. 8uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration - - - - - m + m fi y J/ - - - - < 4 y = 5.02 TeV, 2.5 < NN s ALICE, Pb-Pb < 4 y = 8 TeV, 2.5 < s ALICE, pp < 3.5 y = 7 TeV, 3 < s LHCb, pp - - - - - - - - - - - - - - - - ) c (GeV/ T p ) c (GeV/ T p q l f l fq l Figure 3:
Inclusive J/ ψ polarization parameters as a function of transverse momentum for Pb–Pb collisions at √ s NN = √ s = ψ at √ s = c for better visibility) in therapidity interval 3 < y < .
5. The error bars represent the total uncertainties for the pp results, while for Pb–Pbstatistical and systematic uncertainties are plotted separately as a vertical bar and a shaded box, respectively. Inthe left part of the plot the polarization parameters in the helicity reference frame are reported, in the right thosefor the Collins-Soper frame.
The first measurement of the polarization parameters for J/ ψ production in nuclear collisions at LHCenergies was carried out by the ALICE Collaboration in Pb–Pb interactions at √ s NN = .
02 TeV. The λ θ , λ φ and λ θφ parameters were evaluated in the helicity and Collins-Soper reference frames in therapidity interval 2 . < y < < p T <
10 GeV/ c . All theparameter values are close to zero, with a ∼ . σ indication for a small transverse polarization in thehelicity frame at low p T , and a corresponding indication for a small longitudinal polarization in theCollins-Soper frame ( ∼ . σ effect). When comparing these results with pp data taken at higher energy9uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration Table 3: ϒ ( ) polarization parameters in the helicity and Collins-Soper reference frames measured in Pb–Pbcollisions at √ s NN = .
02 TeV in the rapidity interval 2 . < y < p T <
15 GeV/ c .The first uncertainty is statistical and the second systematic. Helicity Collins-Soper λ θ − . ± . ± .
093 0 . ± . ± . λ φ − . ± . ± . − . ± . ± . λ θφ − . ± . ± .
018 0 . ± . ± . λ HE θ with respect to the LHCb results whichshowed instead a small longitudinal polarization in a similar kinematic domain. This first result obtainedfor J/ ψ in nuclear collisions and described in this Letter represents therefore a starting point for futurestudies connecting such features with the known differences in the production mechanisms between ppand nucleus–nucleus collisions. Results were also obtained for the first time for p T - and y -integrated ϒ ( ) production showing, within the large uncertainties of the measurement, values compatible withthe absence of polarization. Acknowledgements
The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable con-tributions to the construction of the experiment and the CERN accelerator teams for the outstandingperformance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources andsupport provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration.The ALICE Collaboration acknowledges the following funding agencies for their support in buildingand running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics In-stitute) Foundation (ANSL), State Committee of Science and World Federation of Scientists (WFS),Armenia; Austrian Academy of Sciences, Austrian Science Fund (FWF): [M 2467-N36] and National-stiftung für Forschung, Technologie und Entwicklung, Austria; Ministry of Communications and HighTechnologies, National Nuclear Research Center, Azerbaijan; Conselho Nacional de DesenvolvimentoCientífico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (Finep), Fundação de Amparo àPesquisa do Estado de São Paulo (FAPESP) and Universidade Federal do Rio Grande do Sul (UFRGS),Brazil; Ministry of Education of China (MOEC) , Ministry of Science & Technology of China (MSTC)and National Natural Science Foundation of China (NSFC), China; Ministry of Science and Educationand Croatian Science Foundation, Croatia; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear(CEADEN), Cubaenergía, Cuba; Ministry of Education, Youth and Sports of the Czech Republic, CzechRepublic; The Danish Council for Independent Research | Natural Sciences, the VILLUM FONDEN andDanish National Research Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP), Finland;Commissariat à l’Energie Atomique (CEA) and Institut National de Physique Nucléaire et de Physiquedes Particules (IN2P3) and Centre National de la Recherche Scientifique (CNRS), France; Bundesmin-isterium für Bildung und Forschung (BMBF) and GSI Helmholtzzentrum für SchwerionenforschungGmbH, Germany; General Secretariat for Research and Technology, Ministry of Education, Researchand Religions, Greece; National Research, Development and Innovation Office, Hungary; Departmentof Atomic Energy Government of India (DAE), Department of Science and Technology, Governmentof India (DST), University Grants Commission, Government of India (UGC) and Council of Scientificand Industrial Research (CSIR), India; Indonesian Institute of Science, Indonesia; Centro Fermi - MuseoStorico della Fisica e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucleare(INFN), Italy; Institute for Innovative Science and Technology , Nagasaki Institute of Applied Science(IIST), Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and Japan So-ciety for the Promotion of Science (JSPS) KAKENHI, Japan; Consejo Nacional de Ciencia (CONACYT)10uarkonium polarization in nuclear collisions at the LHC ALICE Collaborationy Tecnología, through Fondo de Cooperación Internacional en Ciencia y Tecnología (FONCICYT) andDirección General de Asuntos del Personal Academico (DGAPA), Mexico; Nederlandse Organisatievoor Wetenschappelijk Onderzoek (NWO), Netherlands; The Research Council of Norway, Norway;Commission on Science and Technology for Sustainable Development in the South (COMSATS), Pak-istan; Pontificia Universidad Católica del Perú, Peru; Ministry of Science and Higher Education, NationalScience Centre and WUT ID-UB, Poland; Korea Institute of Science and Technology Information andNational Research Foundation of Korea (NRF), Republic of Korea; Ministry of Education and ScientificResearch, Institute of Atomic Physics and Ministry of Research and Innovation and Institute of AtomicPhysics, Romania; Joint Institute for Nuclear Research (JINR), Ministry of Education and Science ofthe Russian Federation, National Research Centre Kurchatov Institute, Russian Science Foundation andRussian Foundation for Basic Research, Russia; Ministry of Education, Science, Research and Sport ofthe Slovak Republic, Slovakia; National Research Foundation of South Africa, South Africa; SwedishResearch Council (VR) and Knut & Alice Wallenberg Foundation (KAW), Sweden; European Organi-zation for Nuclear Research, Switzerland; Suranaree University of Technology (SUT), National Scienceand Technology Development Agency (NSDTA) and Office of the Higher Education Commission underNRU project of Thailand, Thailand; Turkish Atomic Energy Agency (TAEK), Turkey; National Academyof Sciences of Ukraine, Ukraine; Science and Technology Facilities Council (STFC), United Kingdom;National Science Foundation of the United States of America (NSF) and United States Department ofEnergy, Office of Nuclear Physics (DOE NP), United States of America.
References [1] G. T. Bodwin, E. Braaten, and G. P. Lepage, “Rigorous QCD analysis of inclusive annihilation andproduction of heavy quarkonium,”
Phys. Rev.
D51 (1995) 1125–1171, arXiv:hep-ph/9407339[hep-ph] . [Erratum: Phys. Rev.D55,5853(1997)].[2]
ALICE
Collaboration, S. Acharya et al. , “Energy dependence of forward-rapidity J / ψ and ψ ( ) production in pp collisions at the LHC,” Eur. Phys. J.
C77 no. 6, (2017) 392, arXiv:1702.00557[hep-ex] .[3]
ALICE
Collaboration, S. Acharya et al. , “Inclusive J/ ψ production at mid-rapidity in pp collisionsat √ s = 5.02 TeV,” JHEP (2019) 084, arXiv:1905.07211 [nucl-ex] .[4] LHCb
Collaboration, R. Aaij et al. , “Measurement of forward J / ψ production cross-sections in pp collisions at √ s =
13 TeV,”
JHEP (2015) 172, arXiv:1509.00771 [hep-ex] . [Erratum:JHEP05,063(2017)].[5] CMS
Collaboration, A. M. Sirunyan et al. , “Measurement of quarkonium production crosssections in pp collisions at √ s =
13 TeV,”
Phys. Lett.
B780 (2018) 251–272, arXiv:1710.11002[hep-ex] .[6]
ATLAS
Collaboration, G. Aad et al. , “Measurement of the differential cross-sections of promptand non-prompt production of J / ψ and ψ ( ) in pp collisions at √ s = Eur. Phys. J.
C76 no. 5, (2016) 283, arXiv:1512.03657 [hep-ex] .[7]
PHENIX
Collaboration, U. Acharya et al. , “ J / ψ and ψ ( S ) production at forward rapidity in p + p collisions at √ s =
510 GeV,”
Phys. Rev. D no. 5, (2020) 052006, arXiv:1912.13424[hep-ex] .[8]
STAR
Collaboration, J. Adam et al. , “Measurements of the transverse-momentum-dependentcross sections of J / ψ production at mid-rapidity in proton+proton collisions at √ s =
510 and 500GeV with the STAR detector,”
Phys. Rev.
D100 no. 5, (2019) 052009, arXiv:1905.06075[hep-ex] . 11uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration[9]
CDF
Collaboration, F. Abe et al. , “ J / ψ and ψ ( S ) production in p ¯ p collisions at √ s = . Phys. Rev. Lett. (1997) 572–577.[10] D0 Collaboration, S. Abachi et al. , “ J / ψ production in p ¯ p collisions at √ s = 1.8-TeV,” Phys. Lett.
B370 (1996) 239–248.[11]
LHCb
Collaboration, R. Aaij et al. , “Measurement of ϒ production in pp collisions at √ s = 13TeV,” JHEP (2018) 134, arXiv:1804.09214 [hep-ex] . [Erratum: JHEP05,076(2019)].[12] ALICE
Collaboration, J. Adam et al. , “Inclusive quarkonium production at forward rapidity in ppcollisions at √ s = Eur. Phys. J.
C76 no. 4, (2016) 184, arXiv:1509.08258 [hep-ex] .[13]
ATLAS
Collaboration, G. Aad et al. , “Measurement of Upsilon production in 7 TeV pp collisionsat ATLAS,”
Phys. Rev.
D87 no. 5, (2013) 052004, arXiv:1211.7255 [hep-ex] .[14]
Particle Data Group
Collaboration, M. Tanabashi et al. , “Review of Particle Physics,”
Phys. Rev.
D98 no. 3, (2018) 030001.[15] E. Braaten, B. A. Kniehl, and J. Lee, “Polarization of prompt J / ψ at the Tevatron,” Phys. Rev.
D62 (2000) 094005, arXiv:hep-ph/9911436 [hep-ph] .[16] P. Faccioli, C. Lourenco, J. Seixas, and H. K. Wohri, “Towards the experimental clarification ofquarkonium polarization,”
Eur. Phys. J.
C69 (2010) 657–673, arXiv:1006.2738 [hep-ph] .[17]
CDF
Collaboration, T. Affolder et al. , “Measurement of J / ψ and ψ ( S ) polarization in p ¯ p collisions at √ s = . Phys. Rev. Lett. (2000) 2886–2891, arXiv:hep-ex/0004027[hep-ex] .[18] CDF
Collaboration, A. Abulencia et al. , “Polarization of J / ψ and ψ ( S ) Mesons Produced in p ¯ p Collisions at √ s = 1.96-TeV,” Phys. Rev. Lett. (2007) 132001, arXiv:0704.0638 [hep-ex] .[19] ALICE
Collaboration, B. Abelev et al. , “ J / ψ polarization in pp collisions at √ s = Phys.Rev. Lett. (2012) 082001, arXiv:1111.1630 [hep-ex] .[20]
ALICE
Collaboration, S. Acharya et al. , “Measurement of the inclusive J/ ψ polarization atforward rapidity in pp collisions at √ s = TeV,”
Eur. Phys. J.
C78 no. 7, (2018) 562, arXiv:1805.04374 [hep-ex] .[21]
LHCb
Collaboration, R. Aaij et al. , “Measurement of J / ψ polarization in pp collisions at √ s = Eur. Phys. J.
C73 no. 11, (2013) 2631, arXiv:1307.6379 [hep-ex] .[22]
CMS
Collaboration, S. Chatrchyan et al. , “Measurement of the Prompt J / ψ and ψ (2S)Polarizations in pp Collisions at √ s = 7 TeV,” Phys. Lett.
B727 (2013) 381–402, arXiv:1307.6070 [hep-ex] .[23] M. Butenschoen and B. A. Kniehl, “Reconciling J / ψ production at HERA, RHIC, Tevatron, andLHC with NRQCD factorization at next-to-leading order,” Phys. Rev. Lett. (2011) 022003, arXiv:1009.5662 [hep-ph] .[24] Y.-Q. Ma, K. Wang, and K.-T. Chao, “A complete NLO calculation of the J / ψ and ψ (cid:48) productionat hadron colliders,” Phys. Rev.
D84 (2011) 114001, arXiv:1012.1030 [hep-ph] .[25] M. Butenschoen and B. A. Kniehl, “J/ ψ polarization at Tevatron and LHC: Nonrelativistic-QCDfactorization at the crossroads,” Phys. Rev. Lett. (2012) 172002, arXiv:1201.1872[hep-ph] . 12uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration[26] K.-T. Chao, Y.-Q. Ma, H.-S. Shao, K. Wang, and Y.-J. Zhang, “ J / ψ Polarization at HadronColliders in Nonrelativistic QCD,”
Phys. Rev. Lett. (2012) 242004, arXiv:1201.2675[hep-ph] .[27] B. Gong, L.-P. Wan, J.-X. Wang, and H.-F. Zhang, “Polarization for Prompt J/ ψ and ψ ( s ) Production at the Tevatron and LHC,”
Phys. Rev. Lett. no. 4, (2013) 042002, arXiv:1205.6682 [hep-ph] .[28] Y. Feng, B. Gong, C.-H. Chang, and J.-X. Wang, “Remaining parts of the long-standing J / ψ polarization puzzle,” Phys. Rev.
D99 no. 1, (2019) 014044, arXiv:1810.08989 [hep-ph] .[29] Y.-Q. Ma, T. Stebel, and R. Venugopalan, “ J / ψ polarization in the CGC+NRQCD approach,” JHEP (2018) 057, arXiv:1809.03573 [hep-ph] .[30] CMS
Collaboration, S. Chatrchyan et al. , “Measurement of the ϒ (1S), ϒ (2S) and ϒ (3S)polarizations in pp collisions at √ s = Phys. Rev. Lett. no. 8, (2013) 081802, arXiv:1209.2922 [hep-ex] .[31]
LHCb
Collaboration, R. Aaij et al. , “Measurement of the ϒ polarizations in pp collisions at √ s = JHEP (2017) 110, arXiv:1709.01301 [hep-ex] .[32] H. Han, Y.-Q. Ma, C. Meng, H.-S. Shao, Y.-J. Zhang, and K.-T. Chao, “ ϒ ( nS ) and χ b ( nP ) production at hadron colliders in nonrelativistic QCD,” Phys. Rev.
D94 no. 1, (2016) 014028, arXiv:1410.8537 [hep-ph] .[33] P. Braun-Munzinger and J. Wambach, “The Phase Diagram of Strongly-Interacting Matter,”
Rev.Mod. Phys. (2009) 1031–1050, arXiv:0801.4256 [hep-ph] .[34] P. Braun-Munzinger, V. Koch, T. SchÃd’fer, and J. Stachel, “Properties of hot and dense matterfrom relativistic heavy ion collisions,” Phys. Rept. (2016) 76–126, arXiv:1510.00442[nucl-th] .[35] T. Matsui and H. Satz, “J/ ψ Suppression by Quark-Gluon Plasma Formation,”
Phys. Lett.
B178 (1986) 416–422.[36] M. Laine, “A Resummed perturbative estimate for the quarkonium spectral function in hot QCD,”
JHEP (2007) 028, arXiv:0704.1720 [hep-ph] .[37] P. Braun-Munzinger and J. Stachel, “(Non)thermal aspects of charmonium production and a newlook at J/ ψ suppression,” Phys. Lett.
B490 (2000) 196–202, arXiv:nucl-th/0007059[nucl-th] .[38] R. L. Thews, M. Schroedter, and J. Rafelski, “Enhanced J / ψ production in deconfined quarkmatter,” Phys. Rev.
C63 (2001) 054905, arXiv:hep-ph/0007323 [hep-ph] .[39] B. L. Ioffe and D. E. Kharzeev, “Quarkonium polarization in heavy ion collisions as a possiblesignature of the quark gluon plasma,”
Phys. Rev.
C68 (2003) 061902, arXiv:hep-ph/0306176[hep-ph] .[40] H.-S. Shao, Y.-Q. Ma, K. Wang, and K.-T. Chao, “Polarizations of χ c and χ c in promptproduction at the LHC,” Phys. Rev. Lett. no. 18, (2014) 182003, arXiv:1402.2913[hep-ph] .[41]
CMS
Collaboration, A. M. Sirunyan et al. , “Measurement of the χ c1 and χ c2 polarizations inproton-proton collisions at √ s = arXiv:1912.07706 [hep-ex] .13uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration[42] ALICE
Collaboration, K. Aamodt et al. , “The ALICE experiment at the CERN LHC,”
JINST (2008) S08002.[43] ALICE
Collaboration, B. Abelev et al. , “Performance of the ALICE Experiment at the CERNLHC,”
Int. J. Mod. Phys.
A29 (2014) 1430044, arXiv:1402.4476 [nucl-ex] .[44]
ALICE
Collaboration, K. Aamodt et al. , “Rapidity and transverse momentum dependence ofinclusive J/ ψ production in pp collisions at √ s = Phys. Lett.
B704 (2011) 442, arXiv:1105.0380 [hep-ex] .[45]
ALICE
Collaboration, E. Abbas et al. , “Performance of the ALICE VZERO system,”
JINST (2013) P10016, arXiv:1306.3130 [nucl-ex] .[46] ALICE
Collaboration, K. Aamodt et al. , “Alignment of the ALICE Inner Tracking System withcosmic-ray tracks,”
JINST (2010) P03003, arXiv:1001.0502 [physics.ins-det] .[47] ALICE
Collaboration, B. Abelev et al. , “Measurement of the Cross Section for ElectromagneticDissociation with Neutron Emission in Pb-Pb Collisions at √ s NN = 2.76 TeV,” Phys. Rev. Lett. (2012) 252302, arXiv:1203.2436 [nucl-ex] .[48]
ALICE
Collaboration, F. Bossu, M. Gagliardi, and M. Marchisone, “Performance of theRPC-based ALICE muon trigger system at the LHC,”
JINST (2012) T12002, arXiv:1211.1948[physics.ins-det] . [PoSRPC2012,059(2012)].[49] ALICE
Collaboration, B. Abelev et al. , “Centrality determination of Pb-Pb collisions at √ s NN =2.76 TeV with ALICE,” Phys. Rev.
C88 no. 4, (2013) 044909, arXiv:1301.4361 [nucl-ex] .[50]
ALICE
Collaboration, “Centrality determination in heavy ion collisions,”ALICE-PUBLIC-2018-011. http://cds.cern.ch/record/2636623 .[51]
ALICE
Collaboration, “Quarkonium signal extraction in ALICE,” ALICE-PUBLIC-2015-006. https://cds.cern.ch/record/2060096 .[52]
ALICE
Collaboration, S. Acharya et al. , “Studies of J/ ψ production at forward rapidity in Pb-Pbcollisions at √ s NN = 5.02 TeV,” JHEP (2020) 041, arXiv:1909.03158 [nucl-ex] .[53] R. Brun, F. Bruyant, F. Carminati, S. Giani, M. Maire, A. McPherson, G. Patrick, and L. Urban, GEANT: Detector Description and Simulation Tool; Oct 1994 . CERN Program Library. CERN,Geneva, 1993. http://cds.cern.ch/record/1082634 . Long Writeup W5013.[54]
ALICE
Collaboration, B. Abelev et al. , “Measurement of quarkonium production at forwardrapidity in pp collisions at √ s = Eur. Phys. J.
C74 no. 8, (2014) 2974, arXiv:1403.3648[nucl-ex] .[55]
ALICE
Collaboration, S. Acharya et al. , “ ϒ suppression at forward rapidity in Pb-Pb collisions at √ s NN = 5.02 TeV,” Phys. Lett.
B790 (2019) 89–101, arXiv:1805.04387 [nucl-ex] .14uarkonium polarization in nuclear collisions at the LHC ALICE Collaboration
A The ALICE Collaboration
S. Acharya , D. Adamová , A. Adler , J. Adolfsson , M.M. Aggarwal , G. Aglieri Rinella ,M. Agnello , N. Agrawal
10 ,54 , Z. Ahammed , S. Ahmad , S.U. Ahn , Z. Akbar , A. Akindinov ,M. Al-Turany , S.N. Alam
40 ,141 , D.S.D. Albuquerque , D. Aleksandrov , B. Alessandro ,H.M. Alfanda , R. Alfaro Molina , B. Ali , Y. Ali , A. Alici
10 ,26 ,54 , N. Alizadehvandchali ,A. Alkin , J. Alme , T. Alt , L. Altenkamper , I. Altsybeev , M.N. Anaam , C. Andrei ,D. Andreou , A. Andronic , M. Angeletti , V. Anguelov , C. Anson , T. Antiˇci´c , F. Antinori ,P. Antonioli , N. Apadula , L. Aphecetche , H. Appelshäuser , S. Arcelli , R. Arnaldi , M. Arratia ,I.C. Arsene , M. Arslandok , A. Augustinus , R. Averbeck , S. Aziz , M.D. Azmi , A. Badalà ,Y.W. Baek , S. Bagnasco , X. Bai , R. Bailhache , R. Bala , A. Balbino , A. Baldisseri , M. Ball ,S. Balouza , D. Banerjee , R. Barbera , L. Barioglio , G.G. Barnaföldi , L.S. Barnby , V. Barret ,P. Bartalini , C. Bartels , K. Barth , E. Bartsch , F. Baruffaldi , N. Bastid , S. Basu , G. Batigne ,B. Batyunya , D. Bauri , J.L. Bazo Alba , I.G. Bearden , C. Beattie , C. Bedda , N.K. Behera ,I. Belikov , A.D.C. Bell Hechavarria , F. Bellini , R. Bellwied , V. Belyaev , G. Bencedi ,S. Beole , A. Bercuci , Y. Berdnikov , D. Berenyi , R.A. Bertens , D. Berzano , M.G. Besoiu ,L. Betev , A. Bhasin , I.R. Bhat , M.A. Bhat , H. Bhatt , B. Bhattacharjee , A. Bianchi ,L. Bianchi , N. Bianchi , J. Bielˇcík , J. Bielˇcíková , A. Bilandzic , G. Biro , R. Biswas , S. Biswas ,J.T. Blair , D. Blau , C. Blume , G. Boca , F. Bock , A. Bogdanov , S. Boi , J. Bok ,L. Boldizsár , A. Bolozdynya , M. Bombara , G. Bonomi , H. Borel , A. Borissov , H. Bossi ,E. Botta , L. Bratrud , P. Braun-Munzinger , M. Bregant , M. Broz , E. Bruna , G.E. Bruno
33 ,106 ,M.D. Buckland , D. Budnikov , H. Buesching , S. Bufalino , O. Bugnon , P. Buhler , P. Buncic ,Z. Buthelezi
72 ,131 , J.B. Butt , S.A. Bysiak , D. Caffarri , A. Caliva , E. Calvo Villar ,J.M.M. Camacho , R.S. Camacho , P. Camerini , F.D.M. Canedo , A.A. Capon , F. Carnesecchi ,R. Caron , J. Castillo Castellanos , A.J. Castro , E.A.R. Casula , F. Catalano , C. Ceballos Sanchez ,P. Chakraborty , S. Chandra , W. Chang , S. Chapeland , M. Chartier , S. Chattopadhyay ,S. Chattopadhyay , A. Chauvin , C. Cheshkov , B. Cheynis , V. Chibante Barroso ,D.D. Chinellato , S. Cho , P. Chochula , T. Chowdhury , P. Christakoglou , C.H. Christensen ,P. Christiansen , T. Chujo , C. Cicalo , L. Cifarelli
10 ,26 , L.D. Cilladi , F. Cindolo , M.R. Ciupek ,G. Clai
54 ,ii , J. Cleymans , F. Colamaria , D. Colella , A. Collu , M. Colocci , M. Concas
59 ,iii , G. ConesaBalbastre , Z. Conesa del Valle , G. Contin
24 ,60 , J.G. Contreras , T.M. Cormier , Y. Corrales Morales ,P. Cortese , M.R. Cosentino , F. Costa , S. Costanza , P. Crochet , E. Cuautle , P. Cui ,L. Cunqueiro , D. Dabrowski , T. Dahms , A. Dainese , F.P.A. Damas
115 ,137 , M.C. Danisch ,A. Danu , D. Das , I. Das , P. Das , P. Das , S. Das , A. Dash , S. Dash , S. De , A. De Caro ,G. de Cataldo , J. de Cuveland , A. De Falco , D. De Gruttola , N. De Marco , S. De Pasquale ,S. Deb , H.F. Degenhardt , K.R. Deja , A. Deloff , S. Delsanto
25 ,131 , W. Deng , P. Dhankher , D. DiBari , A. Di Mauro , R.A. Diaz , T. Dietel , P. Dillenseger , Y. Ding , R. Divià , D.U. Dixit ,Ø. Djuvsland , U. Dmitrieva , A. Dobrin , B. Dönigus , O. Dordic , A.K. Dubey , A. Dubla
90 ,107 ,S. Dudi , M. Dukhishyam , P. Dupieux , R.J. Ehlers , V.N. Eikeland , D. Elia , B. Erazmus ,F. Erhardt , A. Erokhin , M.R. Ersdal , B. Espagnon , G. Eulisse , D. Evans , S. Evdokimov ,L. Fabbietti , M. Faggin , J. Faivre , F. Fan , A. Fantoni , M. Fasel , P. Fecchio , A. Feliciello ,G. Feofilov , A. Fernández Téllez , A. Ferrero , A. Ferretti , A. Festanti , V.J.G. Feuillard ,J. Figiel , S. Filchagin , D. Finogeev , F.M. Fionda , G. Fiorenza , F. Flor , A.N. Flores ,S. Foertsch , P. Foka , S. Fokin , E. Fragiacomo , U. Frankenfeld , U. Fuchs , C. Furget , A. Furs ,M. Fusco Girard , J.J. Gaardhøje , M. Gagliardi , A.M. Gago , A. Gal , C.D. Galvan , P. Ganoti ,C. Garabatos , J.R.A. Garcia , E. Garcia-Solis , K. Garg , C. Gargiulo , A. Garibli , K. Garner ,P. Gasik
105 ,107 , E.F. Gauger , M.B. Gay Ducati , M. Germain , J. Ghosh , P. Ghosh , S.K. Ghosh ,M. Giacalone , P. Gianotti , P. Giubellino
59 ,107 , P. Giubilato , A.M.C. Glaenzer , P. Glässel , A. GomezRamirez , V. Gonzalez
107 ,143 , L.H. González-Trueba , S. Gorbunov , L. Görlich , A. Goswami ,S. Gotovac , V. Grabski , L.K. Graczykowski , K.L. Graham , L. Greiner , A. Grelli , C. Grigoras ,V. Grigoriev , A. Grigoryan , S. Grigoryan , O.S. Groettvik , F. Grosa
30 ,59 , J.F. Grosse-Oetringhaus ,R. Grosso , R. Guernane , M. Guittiere , K. Gulbrandsen , T. Gunji , A. Gupta , R. Gupta ,I.B. Guzman , R. Haake , M.K. Habib , C. Hadjidakis , H. Hamagaki , G. Hamar , M. Hamid ,R. Hannigan , M.R. Haque
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15 ,133 , P. Hristov , C. Huang ,C. Hughes , P. Huhn , T.J. Humanic , H. Hushnud , L.A. Husova , N. Hussain , S.A. Hussain ,D. Hutter , J.P. Iddon
34 ,127 , R. Ilkaev , H. Ilyas , M. Inaba , G.M. Innocenti , M. Ippolitov ,A. Isakov , M.S. Islam , M. Ivanov , V. Ivanov , V. Izucheev , B. Jacak , N. Jacazio
34 ,54 ,P.M. Jacobs , S. Jadlovska , J. Jadlovsky , S. Jaelani , C. Jahnke , M.J. Jakubowska ,M.A. Janik , T. Janson , M. Jercic , O. Jevons , M. Jin , F. Jonas
96 ,144 , P.G. Jones , J. Jung ,M. Jung , A. Jusko , P. Kalinak , A. Kalweit , V. Kaplin , S. Kar , A. Karasu Uysal , D. Karatovic ,O. Karavichev , T. Karavicheva , P. Karczmarczyk , E. Karpechev , A. Kazantsev , U. Kebschull ,R. Keidel , M. Keil , B. Ketzer , Z. Khabanova , A.M. Khan , S. Khan , A. Khanzadeev ,Y. Kharlov , A. Khatun , A. Khuntia , B. Kileng , B. Kim , B. Kim , D. Kim , D.J. Kim ,E.J. Kim , H. Kim , J. Kim , J.S. Kim , J. Kim , J. Kim , J. Kim , M. Kim , S. Kim ,T. Kim , T. Kim , S. Kirsch , I. Kisel , S. Kiselev , A. Kisiel , J.L. Klay , C. Klein , J. Klein
34 ,59 ,S. Klein , C. Klein-Bösing , M. Kleiner , A. Kluge , M.L. Knichel , A.G. Knospe , C. Kobdaj ,M.K. Köhler , T. Kollegger , A. Kondratyev , N. Kondratyeva , E. Kondratyuk , J. Konig ,S.A. Konigstorfer , P.J. Konopka , G. Kornakov , L. Koska , O. Kovalenko , V. Kovalenko ,M. Kowalski , I. Králik , A. Kravˇcáková , L. Kreis , M. Krivda
64 ,111 , F. Krizek ,K. Krizkova Gajdosova , M. Krüger , E. Kryshen , M. Krzewicki , A.M. Kubera , V. Kuˇcera
34 ,61 ,C. Kuhn , P.G. Kuijer , L. Kumar , S. Kundu , P. Kurashvili , A. Kurepin , A.B. Kurepin ,A. Kuryakin , S. Kushpil , J. Kvapil , M.J. Kweon , J.Y. Kwon , Y. Kwon , S.L. La Pointe , P. LaRocca , Y.S. Lai , M. Lamanna , R. Langoy , K. Lapidus , A. Lardeux , P. Larionov , E. Laudi ,R. Lavicka , T. Lazareva , R. Lea , L. Leardini , J. Lee , S. Lee , S. Lehner , J. Lehrbach ,R.C. Lemmon , I. León Monzón , E.D. Lesser , M. Lettrich , P. Lévai , X. Li , X.L. Li , J. Lien ,R. Lietava , B. Lim , V. Lindenstruth , A. Lindner , C. Lippmann , M.A. Lisa , A. Liu , J. Liu ,S. Liu , W.J. Llope , I.M. Lofnes , V. Loginov , C. Loizides , P. Loncar , J.A. Lopez , X. Lopez ,E. López Torres , J.R. Luhder , M. Lunardon , G. Luparello , Y.G. Ma , A. Maevskaya , M. Mager ,S.M. Mahmood , T. Mahmoud , A. Maire , R.D. Majka
146 ,i , M. Malaev , Q.W. Malik , L. Malinina
75 ,iv ,D. Mal’Kevich , P. Malzacher , G. Mandaglio
32 ,56 , V. Manko , F. Manso , V. Manzari , Y. Mao ,M. Marchisone , J. Mareš , G.V. Margagliotti , A. Margotti , A. Marín , C. Markert ,M. Marquard , C.D. Martin , N.A. Martin , P. Martinengo , J.L. Martinez , M.I. Martínez ,G. Martínez García , S. Masciocchi , M. Masera , A. Masoni , L. Massacrier , E. Masson ,A. Mastroserio
53 ,138 , A.M. Mathis , O. Matonoha , P.F.T. Matuoka , A. Matyja , C. Mayer ,F. Mazzaschi , M. Mazzilli , M.A. Mazzoni , A.F. Mechler , F. Meddi , Y. Melikyan
62 ,93 ,A. Menchaca-Rocha , C. Mengke , E. Meninno
29 ,114 , A.S. Menon , M. Meres , S. Mhlanga ,Y. Miake , L. Micheletti , L.C. Migliorin , D.L. Mihaylov , K. Mikhaylov
75 ,92 , A.N. Mishra ,D. Mi´skowiec , A. Modak , N. Mohammadi , A.P. Mohanty , B. Mohanty , M. Mohisin Khan
16 ,v ,Z. Moravcova , C. Mordasini , D.A. Moreira De Godoy , L.A.P. Moreno , I. Morozov , A. Morsch ,T. Mrnjavac , V. Muccifora , E. Mudnic , D. Mühlheim , S. Muhuri , J.D. Mulligan , A. Mulliri
23 ,55 ,M.G. Munhoz , R.H. Munzer , H. Murakami , S. Murray , L. Musa , J. Musinsky , C.J. Myers ,J.W. Myrcha , B. Naik , R. Nair , B.K. Nandi , R. Nania
10 ,54 , E. Nappi , M.U. Naru ,A.F. Nassirpour , C. Nattrass , R. Nayak , T.K. Nayak , S. Nazarenko , A. Neagu , R.A. Negrao DeOliveira , L. Nellen , S.V. Nesbo , G. Neskovic , D. Nesterov , L.T. Neumann , B.S. Nielsen ,S. Nikolaev , S. Nikulin , V. Nikulin , F. Noferini
10 ,54 , P. Nomokonov , J. Norman
79 ,127 , N. Novitzky ,P. Nowakowski , A. Nyanin , J. Nystrand , M. Ogino , A. Ohlson
81 ,104 , J. Oleniacz , A.C. Oliveira DaSilva , M.H. Oliver , C. Oppedisano , A. Ortiz Velasquez , A. Oskarsson , J. Otwinowski ,K. Oyama , Y. Pachmayer , V. Pacik , S. Padhan , D. Pagano , G. Pai´c , J. Pan , S. Panebianco ,P. Pareek
50 ,141 , J. Park , J.E. Parkkila , S. Parmar , S.P. Pathak , B. Paul , J. Pazzini , H. Pei ,T. Peitzmann , X. Peng , L.G. Pereira , H. Pereira Da Costa , D. Peresunko , G.M. Perez , S. Perrin ,Y. Pestov , V. Petráˇcek , M. Petrovici , R.P. Pezzi , S. Piano , M. Pikna , P. Pillot , O. Pinazza
34 ,54 ,L. Pinsky , C. Pinto , S. Pisano
10 ,52 , D. Pistone , M. Płosko´n , M. Planinic , F. Pliquett ,M.G. Poghosyan , B. Polichtchouk , N. Poljak , A. Pop , S. Porteboeuf-Houssais , V. Pozdniakov ,S.K. Prasad , R. Preghenella , F. Prino , C.A. Pruneau , I. Pshenichnov , M. Puccio , J. Putschke ,S. Qiu , L. Quaglia , R.E. Quishpe , S. Ragoni , S. Raha , S. Rajput , J. Rak ,A. Rakotozafindrabe , L. Ramello , F. Rami , S.A.R. Ramirez , R. Raniwala , S. Raniwala ,S.S. Räsänen , R. Rath , V. Ratza , I. Ravasenga , K.F. Read
96 ,130 , A.R. Redelbach , K. Redlich
85 ,vi ,A. Rehman , P. Reichelt , F. Reidt , X. Ren , R. Renfordt , Z. Rescakova , K. Reygers , A. Riabov ,V. Riabov , T. Richert
81 ,89 , M. Richter , P. Riedler , W. Riegler , F. Riggi , C. Ristea , S.P. Rode , M. Rodríguez Cahuantzi , K. Røed , R. Rogalev , E. Rogochaya , D. Rohr , D. Röhrich , P.F. Rojas ,P.S. Rokita , F. Ronchetti , A. Rosano , E.D. Rosas , K. Roslon , P. Rosnet , A. Rossi
28 ,57 ,A. Rotondi , A. Roy , P. Roy , O.V. Rueda , R. Rui , B. Rumyantsev , A. Rustamov ,E. Ryabinkin , Y. Ryabov , A. Rybicki , H. Rytkonen , O.A.M. Saarimaki , R. Sadek , S. Sadhu ,S. Sadovsky , K. Šafaˇrík , S.K. Saha , B. Sahoo , P. Sahoo , R. Sahoo , S. Sahoo , P.K. Sahu ,J. Saini , S. Sakai , S. Sambyal , V. Samsonov
93 ,98 , D. Sarkar , N. Sarkar , P. Sarma ,V.M. Sarti , M.H.P. Sas , E. Scapparone , J. Schambach , H.S. Scheid , C. Schiaua , R. Schicker ,A. Schmah , C. Schmidt , H.R. Schmidt , M.O. Schmidt , M. Schmidt , N.V. Schmidt
68 ,96 ,A.R. Schmier , J. Schukraft , Y. Schutz , K. Schwarz , K. Schweda , G. Scioli , E. Scomparin ,J.E. Seger , Y. Sekiguchi , D. Sekihata , I. Selyuzhenkov
93 ,107 , S. Senyukov , D. Serebryakov ,A. Sevcenco , A. Shabanov , A. Shabetai , R. Shahoyan , W. Shaikh , A. Shangaraev , A. Sharma ,A. Sharma , H. Sharma , M. Sharma , N. Sharma , S. Sharma , O. Sheibani , K. Shigaki ,M. Shimomura , S. Shirinkin , Q. Shou , Y. Sibiriak , S. Siddhanta , T. Siemiarczuk , D. Silvermyr ,G. Simatovic , G. Simonetti , B. Singh , R. Singh , R. Singh , R. Singh , V.K. Singh ,V. Singhal , T. Sinha , B. Sitar , M. Sitta , T.B. Skaali , M. Slupecki , N. Smirnov ,R.J.M. Snellings , C. Soncco , J. Song , A. Songmoolnak , F. Soramel , S. Sorensen ,I. Sputowska , J. Stachel , I. Stan , P.J. Steffanic , E. Stenlund , S.F. Stiefelmaier , D. Stocco ,M.M. Storetvedt , L.D. Stritto , A.A.P. Suaide , T. Sugitate , C. Suire , M. Suleymanov , M. Suljic ,R. Sultanov , M. Šumbera , V. Sumberia , S. Sumowidagdo , S. Swain , A. Szabo , I. Szarka ,U. Tabassam , S.F. Taghavi , G. Taillepied , J. Takahashi , G.J. Tambave , S. Tang ,M. Tarhini , M.G. Tarzila , A. Tauro , G. Tejeda Muñoz , A. Telesca , L. Terlizzi , C. Terrevoli ,D. Thakur , S. Thakur , D. Thomas , F. Thoresen , R. Tieulent , A. Tikhonov , A.R. Timmins ,A. Toia , N. Topilskaya , M. Toppi , F. Torales-Acosta , S.R. Torres , A. Trifiró
32 ,56 , S. Tripathy
50 ,69 ,T. Tripathy , S. Trogolo , G. Trombetta , L. Tropp , V. Trubnikov , W.H. Trzaska , T.P. Trzcinski ,B.A. Trzeciak
37 ,63 , A. Tumkin , R. Turrisi , T.S. Tveter , K. Ullaland , E.N. Umaka , A. Uras ,G.L. Usai , M. Vala , N. Valle , S. Vallero , N. van der Kolk , L.V.R. van Doremalen , M. vanLeeuwen , P. Vande Vyvre , D. Varga , Z. Varga , M. Varga-Kofarago , A. Vargas , M. Vasileiou ,A. Vasiliev , O. Vázquez Doce , V. Vechernin , E. Vercellin , S. Vergara Limón , L. Vermunt ,R. Vernet , R. Vértesi , L. Vickovic , Z. Vilakazi , O. Villalobos Baillie , G. Vino , A. Vinogradov ,T. Virgili , V. Vislavicius , A. Vodopyanov , B. Volkel , M.A. Völkl , K. Voloshin , S.A. Voloshin ,G. Volpe , B. von Haller , I. Vorobyev , D. Voscek , J. Vrláková , B. Wagner , M. Weber ,S.G. Weber , A. Wegrzynek , S.C. Wenzel , J.P. Wessels , J. Wiechula , J. Wikne , G. Wilk ,J. Wilkinson
10 ,54 , G.A. Willems , E. Willsher , B. Windelband , M. Winn , W.E. Witt ,J.R. Wright , Y. Wu , R. Xu , S. Yalcin , Y. Yamaguchi , K. Yamakawa , S. Yang , S. Yano ,Z. Yin , H. Yokoyama , I.-K. Yoo , J.H. Yoon , S. Yuan , A. Yuncu , V. Yurchenko , V. Zaccolo ,A. Zaman , C. Zampolli , H.J.C. Zanoli , N. Zardoshti , A. Zarochentsev , P. Závada ,N. Zaviyalov , H. Zbroszczyk , M. Zhalov , S. Zhang , X. Zhang , Z. Zhang , V. Zherebchevskii ,Y. Zhi , D. Zhou , Y. Zhou , Z. Zhou , J. Zhu , Y. Zhu , A. Zichichi
10 ,26 , G. Zinovjev , N. Zurlo , Affiliation notes i Deceased ii Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA),Bologna, Italy iii
Dipartimento DET del Politecnico di Torino, Turin, Italy iv M.V. Lomonosov Moscow State University, D.V. Skobeltsyn Institute of Nuclear, Physics, Moscow, Russia v Department of Applied Physics, Aligarh Muslim University, Aligarh, India vi Institute of Theoretical Physics, University of Wroclaw, Poland
Collaboration Institutes A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation, Yerevan, Armenia Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine Bose Institute, Department of Physics and Centre for Astroparticle Physics and Space Science (CAPSS),Kolkata, India Budker Institute for Nuclear Physics, Novosibirsk, Russia California Polytechnic State University, San Luis Obispo, California, United States Central China Normal University, Wuhan, China Centre de Calcul de l’IN2P3, Villeurbanne, Lyon, France Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi’, Rome, Italy Chicago State University, Chicago, Illinois, United States China Institute of Atomic Energy, Beijing, China Comenius University Bratislava, Faculty of Mathematics, Physics and Informatics, Bratislava, Slovakia COMSATS University Islamabad, Islamabad, Pakistan Creighton University, Omaha, Nebraska, United States Department of Physics, Aligarh Muslim University, Aligarh, India Department of Physics, Pusan National University, Pusan, Republic of Korea Department of Physics, Sejong University, Seoul, Republic of Korea Department of Physics, University of California, Berkeley, California, United States Department of Physics, University of Oslo, Oslo, Norway Department of Physics and Technology, University of Bergen, Bergen, Norway Dipartimento di Fisica dell’Università ’La Sapienza’ and Sezione INFN, Rome, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Turin, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Bologna, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Padova, Italy Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Gruppo Collegato INFN, Salerno, Italy Dipartimento DISAT del Politecnico and Sezione INFN, Turin, Italy Dipartimento di Scienze e Innovazione Tecnologica dell’Università del Piemonte Orientale and INFNSezione di Torino, Alessandria, Italy Dipartimento di Scienze MIFT, Università di Messina, Messina, Italy Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy European Organization for Nuclear Research (CERN), Geneva, Switzerland Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split,Split, Croatia Faculty of Engineering and Science, Western Norway University of Applied Sciences, Bergen, Norway Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague,Czech Republic Faculty of Science, P.J. Šafárik University, Košice, Slovakia Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt,Germany Fudan University, Shanghai, China Gangneung-Wonju National University, Gangneung, Republic of Korea Gauhati University, Department of Physics, Guwahati, India Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn,Germany Helsinki Institute of Physics (HIP), Helsinki, Finland High Energy Physics Group, Universidad Autónoma de Puebla, Puebla, Mexico Hiroshima University, Hiroshima, Japan Hochschule Worms, Zentrum für Technologietransfer und Telekommunikation (ZTT), Worms, Germany Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania Indian Institute of Technology Bombay (IIT), Mumbai, India Indian Institute of Technology Indore, Indore, India Indonesian Institute of Sciences, Jakarta, Indonesia INFN, Laboratori Nazionali di Frascati, Frascati, Italy INFN, Sezione di Bari, Bari, Italy INFN, Sezione di Bologna, Bologna, Italy INFN, Sezione di Cagliari, Cagliari, Italy INFN, Sezione di Catania, Catania, Italy INFN, Sezione di Padova, Padova, Italy INFN, Sezione di Roma, Rome, Italy INFN, Sezione di Torino, Turin, Italy INFN, Sezione di Trieste, Trieste, Italy Inha University, Incheon, Republic of Korea Institute for Nuclear Research, Academy of Sciences, Moscow, Russia Institute for Subatomic Physics, Utrecht University/Nikhef, Utrecht, Netherlands Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia Institute of Physics, Homi Bhabha National Institute, Bhubaneswar, India Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic Institute of Space Science (ISS), Bucharest, Romania Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico iThemba LABS, National Research Foundation, Somerset West, South Africa Jeonbuk National University, Jeonju, Republic of Korea Johann-Wolfgang-Goethe Universität Frankfurt Institut für Informatik, Fachbereich Informatik undMathematik, Frankfurt, Germany Joint Institute for Nuclear Research (JINR), Dubna, Russia Korea Institute of Science and Technology Information, Daejeon, Republic of Korea KTO Karatay University, Konya, Turkey Laboratoire de Physique des 2 Infinis, Irène Joliot-Curie, Orsay, France Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS-IN2P3,Grenoble, France Lawrence Berkeley National Laboratory, Berkeley, California, United States Lund University Department of Physics, Division of Particle Physics, Lund, Sweden Nagasaki Institute of Applied Science, Nagasaki, Japan Nara Women’s University (NWU), Nara, Japan National and Kapodistrian University of Athens, School of Science, Department of Physics , Athens,Greece National Centre for Nuclear Research, Warsaw, Poland National Institute of Science Education and Research, Homi Bhabha National Institute, Jatni, India National Nuclear Research Center, Baku, Azerbaijan National Research Centre Kurchatov Institute, Moscow, Russia Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark Nikhef, National institute for subatomic physics, Amsterdam, Netherlands NRC Kurchatov Institute IHEP, Protvino, Russia NRC «Kurchatov» Institute - ITEP, Moscow, Russia NRNU Moscow Engineering Physics Institute, Moscow, Russia Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, United Kingdom Nuclear Physics Institute of the Czech Academy of Sciences, ˇRež u Prahy, Czech Republic Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States Ohio State University, Columbus, Ohio, United States Petersburg Nuclear Physics Institute, Gatchina, Russia Physics department, Faculty of science, University of Zagreb, Zagreb, Croatia
Physics Department, Panjab University, Chandigarh, India
Physics Department, University of Jammu, Jammu, India
Physics Department, University of Rajasthan, Jaipur, India
Physikalisches Institut, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
Physik Department, Technische Universität München, Munich, Germany
Politecnico di Bari, Bari, Italy
Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fürSchwerionenforschung GmbH, Darmstadt, Germany
Rudjer Boškovi´c Institute, Zagreb, Croatia
Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom
Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru
St. Petersburg State University, St. Petersburg, Russia
Stefan Meyer Institut für Subatomare Physik (SMI), Vienna, Austria
SUBATECH, IMT Atlantique, Université de Nantes, CNRS-IN2P3, Nantes, France
Suranaree University of Technology, Nakhon Ratchasima, Thailand
Technical University of Košice, Košice, Slovakia
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
The University of Texas at Austin, Austin, Texas, United States
Universidad Autónoma de Sinaloa, Culiacán, Mexico
Universidade de São Paulo (USP), São Paulo, Brazil
Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
Universidade Federal do ABC, Santo Andre, Brazil
University of Cape Town, Cape Town, South Africa
University of Houston, Houston, Texas, United States
University of Jyväskylä, Jyväskylä, Finland
University of Liverpool, Liverpool, United Kingdom
University of Science and Technology of China, Hefei, China
University of South-Eastern Norway, Tonsberg, Norway
University of Tennessee, Knoxville, Tennessee, United States
University of the Witwatersrand, Johannesburg, South Africa
University of Tokyo, Tokyo, Japan
University of Tsukuba, Tsukuba, Japan
Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, Lyon, France
Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France, Strasbourg, France
Université Paris-Saclay Centre d’Etudes de Saclay (CEA), IRFU, Départment de Physique Nucléaire(DPhN), Saclay, France
Università degli Studi di Foggia, Foggia, Italy
Università degli Studi di Pavia, Pavia, Italy
Università di Brescia, Brescia, Italy
Variable Energy Cyclotron Centre, Homi Bhabha National Institute, Kolkata, India
Warsaw University of Technology, Warsaw, Poland
Wayne State University, Detroit, Michigan, United States
Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
Wigner Research Centre for Physics, Budapest, Hungary
Yale University, New Haven, Connecticut, United States