Search for anomalous production of events with three or more leptons in pp collisions at sqrt(s) = 8 TeV
EEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-PH-EP/2013-0372014/08/22
CMS-SUS-13-002
Search for anomalous production of events with three ormore leptons in pp collisions at √ s = The CMS Collaboration ∗ Abstract
A search for physics beyond the standard model in events with at least three lep-tons is presented. The data sample, corresponding to an integrated luminosity of19.5 fb − of proton-proton collisions with center-of-mass energy √ s = τ leptons, and the magnitude of the missing transverseenergy and of the scalar sum of jet transverse momenta. The numbers of observedevents are found to be consistent with the expected numbers from standard modelprocesses, and limits are placed on new-physics scenarios that yield multilepton finalstates. In particular, scenarios that predict Higgs boson production in the context ofsupersymmetric decay chains are examined. We also place a 95% confidence levelupper limit of 1.3% on the branching fraction for the decay of a top quark to a charmquark and a Higgs boson (t → cH), which translates to a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, λ Htc and λ Hct , respectively,of (cid:113) | λ Htc | + | λ Hct | < Published in Physical Review D as doi:10.1103/PhysRevD.90.032006. c (cid:13) ∗ See Appendix A for the list of collaboration members a r X i v : . [ h e p - e x ] A ug The recent discovery of a Higgs boson [1–3] at the relatively low mass of about 125 GeV impliesthat physics beyond the standard model (BSM) may be observable at energy scales of around1 TeV. Supersymmetry (SUSY) is a prominent candidate for BSM physics because it providesa solution to the hierarchy problem, predicts gauge-coupling unification, and contains a “nat-ural” candidate for dark matter [4–6]. Supersymmetry postulates the existence of fermionicsuperpartners for each standard model (SM) boson, and of bosonic superpartners for each SMfermion. For example, gluinos, squarks, and winos are the superpartners of gluons, quarks,and W bosons, respectively. The superparter of a lepton is a slepton. In R -parity [7] conservingSUSY models, supersymmetric particles are created in pairs, and the lightest supersymmet-ric particle (LSP) is stable. If the LSP interacts only weakly, as in the case of a dark mattercandidate, it escapes detection, leading to missing transverse energy ( E missT ). Here, R -parity isdefined by R = ( − ) B + L + s , with B and L the baryon and lepton numbers, and s the particlespin. All SM particles have R = + R = − τ leptons. Direct pair pro-duction of the superpartners of the electron and muon (selectron and smuon, respectively)can yield a multilepton state dominated by τ leptons should the superpartner of the τ lepton(stau) be substantially lighter than the selectron and smuon, as is expected in some models.Another path to a multileptonic final state arises from top-squark production in which the topsquark decays to leptonically decaying third-generation quarks and to a Z boson that yields anopposite-sign same-flavor (OSSF) lepton pair. In these latter events, bottom-quark jets (b jets)might also be present. Similarly, many other multileptonic signatures are possible.Besides SUSY, other BSM scenarios can yield multileptonic final states, such as t → cH tran-sitions, with t a top quark, c a charm quark, and H a Higgs boson. The t → cH process isextremely rare in the SM but can be enhanced through the production of new particles inloops [9, 10]. The top quark is the heaviest SM particle, and is thus the SM particle that ismost strongly coupled to the Higgs boson. Since the t → cH process directly probes the flavor-violating couplings of the top quark to the Higgs boson, it provides a powerful means to searchfor BSM physics regardless of the underlying new-physics mechanism. The t → cH decay cangive rise to a multilepton signature when a top quark in a top quark-antiquark (tt) pair decaysto the cH state, followed by the decay of the Higgs boson to leptons through, e.g., H → ZZ ∗ orH → WW ∗ decays, in conjunction with the leptonic decay of the other top quark in the tt pair.In this paper, we present a search for BSM physics in multilepton channels. The search is basedon a sample of proton-proton collision data collected at √ s = − . The study is an extension of our earlier work [11],which was based on a data set of 5.0 fb − collected at √ s = R -parity-violating SUSY scenarios. Refer-ences [13–17] contain recent, related results from the ATLAS Collaboration, and Refs. [12, 18–27] contain the same from CMS. Because of the wide range of possible BSM signatures, we have adopted a search strategy thatis sensitive to different kinematical and topological signatures, rather than optimizing the anal-ysis for a particular model. We retain all observed multilepton candidate events and classifythem into multiple mutually exclusive categories based on the number of leptons, the leptonflavor, the presence of b jets, the presence of an OSSF pair indicative of a Z boson, and kinematiccharacteristics such as E missT and H T , where H T is the scalar sum of jet transverse momentum( p T ) values. We then confront a number of BSM scenarios that exhibit diverse characteristicswith respect to the population of these categories.This paper is organized as follows. In Sec. 2, a brief summary of the CMS detector and a de-scription of the trigger is presented. Section 3 discusses the event reconstruction procedures,event selection, and event simulation. The search strategy and the background evaluationmethods are outlined in Secs. 4 and 5. Section 6 contains a discussion of systematic uncertain-ties. The results are presented in Sec. 7. Sections 8 and 9 present the interpretations of ourresults for SUSY scenarios and for the t → cH process, respectively. A summary is given inSec. 10. The CMS detector has cylindrical symmetry around the direction of the beam axis. The co-ordinate system is defined with the origin at the nominal collision point and the z axis alongthe direction of the counterclockwise proton beam. The x axis points toward the center of theLHC ring and the y axis vertically upwards. The polar angle θ is measured with respect tothe z axis. The azimuthal angle φ is measured in the x − y plane, relative to the x axis. Bothangles are measured in radians. Pseudorapidity η is defined as η = − ln [ tan ( θ /2 )] . The centralfeature of the detector is a superconducting solenoidal magnet of field strength 3.8 T. Withinthe field volume are a silicon pixel and strip tracker, a lead tungstate crystal calorimeter, anda brass-and-scintillator hadron calorimeter. The tracking detector covers the region | η | < | η | < | η | < | η | < µµ , or e µ ) is used for data collection. At the trigger level, theleptons with the highest and second-highest transverse momentum are required to satisfy p T >
17 GeV and p T > H T [11]. After application of allselection requirements, the trigger efficiencies are found to be 95%, 90%, and 93%, respectively,for the ee, µµ , and e µ triggers. Corrections are applied to account for the trigger inefficiencies. The particle-flow (PF) method [29, 30] is used to reconstruct the physics objects used in thisanalysis: electrons, muons, hadronically decaying τ leptons ( τ h ), jets, and E missT .Electrons and muons are reconstructed using measured quantities from the tracker, calorimeter,and muon system. The candidate tracks must satisfy quality requirements and spatially matchenergy deposits in the electromagnetic calorimeter or tracks in the muon detectors, as appro-priate. Details of the reconstruction and identification procedures can be found in Ref. [31] forelectrons and in Ref. [32] for muons.Hadronically decaying τ leptons predominantly yield either a single charged track (one-prong decays) or three charged tracks (three-prong decays) with or without additional electromag-netic energy from neutral-pion decays. Both one-prong and three-prong τ h decays are recon-structed using the hadron plus strips algorithm [33].The event primary vertex is defined to be the reconstructed vertex with the largest sum ofcharged-track p value and is required to lie within 24 cm of the origin in the direction alongthe z axis and 2 cm in the transverse plane.Jets are formed from reconstructed PF objects using the anti- k T algorithm [34, 35] with a dis-tance parameter of 0.5. Corrections are applied as a function of jet p T and η to account fornonuniform detector response [36]. Contributions to the jet p T values due to overlapping ppinteractions from the same or neighboring bunch crossing (”pileup”) are subtracted using thejet area method described in Ref. [37].Finally, E missT is the magnitude of the vector sum of the transverse momenta of all PF objects.We require the presence of at least three reconstructed leptons, where by ”lepton” we mean anelectron, muon, or τ h candidate. Electron and muon candidates must satisfy p T >
10 GeV and | η | < p T >
20 GeV. The τ h candidatesmust satisfy p T >
20 GeV and | η | < τ h candidate.Leptonically decaying τ leptons populate the electron and muon channels.Leptons from BSM processes are typically isolated, i.e., separated in ∆ R ≡ (cid:112) ( ∆ η ) + ( ∆ φ ) from other physics objects. To reduce background from the semileptonic decays of heavy quarkflavors, which generally yield leptons within jets, we apply lepton isolation criteria. For elec-trons and muons, we define the relative isolation I rel to be the sum of the p T values of all PFobjects within a cone of radius ∆ R = p T value, and require I rel < τ h leptons, the sum of en-ergy E τ h iso within a cone of radius ∆ R = E τ h iso < (cid:96) + (cid:96) − combinations, with (cid:96) an electron or muon.Events with an OSSF pair that satisfies m (cid:96) + (cid:96) − <
12 GeV are rejected to eliminate backgroundfrom low-mass Drell–Yan processes and J/ ψ and Υ decays. If there is more than one OSSFpair in the event, this requirement is applied to each pair. Events with an OSSF pair outsidethe Z boson mass region (defined by 75 < m (cid:96) + (cid:96) − <
105 GeV) but that satisfy 75 < m (cid:96) + (cid:96) − (cid:96) ( (cid:48) ) ± <
105 GeV, where (cid:96) ( (cid:48) ) ± is an electron or muon with the same (different) flavor as the OSSF pair, arelikely to arise from final-state photon radiation from the Z-boson decay products, followed byconversion of the photon to a charged lepton pair. Events that meet this condition are rejectedif they also exhibit kinematic characteristics consistent with background from events with a Zboson and jets (Z+jets background).Jets are required to satisfy p T >
30 GeV and | η | < ∆ R = p T value of80 GeV, with a misidentification rate for light-flavor events of less than 2% and for charm-quarkjets of roughly 20%. Samples of simulated events are used to determine signal acceptance and to evaluate some SMbackgrounds. The simulation of SM events is based on the M AD G RAPH (version 5.1.3.30) [39]event generator with leading-order CTEQ6L1 [40] parton distribution functions (PDF), with theG
EANT AD G RAPH and
PYTHIA (version 6.420) [45] generators, with the description of detectorresponse based on the CMS fast simulation program [46]. Parton showering for all simulatedevents is described using
PYTHIA . The simulated events are adjusted to account for the multi-plicity of pileup interactions observed in the data, as well as for differences between data andsimulation for the jet energy scale, rate of events with initial-state radiation (ISR) [23], and b-jettagging efficiency [38].
Multilepton event candidates are separated into mutually exclusive search channels. The levelof the SM background varies considerably between the different categories. The overall sen-sitivity to new physics is maximized by separating the low- and high-background channels.Events with exactly three leptons generally suffer from a higher background level than eventswith four or more leptons, as do events with a τ h candidate. We therefore categorize eventswith three leptons separately from those with four or more, and events with a τ h candidateseparately from those without such a candidate. Similarly, events with a tagged b jet sufferhigher background from tt events, and so are categorized separately from events without atagged b jet.We also define categories based on the number n of OSSF dilepton pairs that can be formed us-ing each lepton candidate only once (OSSF n ). For example, both µ + µ − µ − and µ + µ − e − eventsfall into the OSSF1 category, while µ + µ + e − and µ + µ − e + e − events fall into the OSSF0 andOSSF2 categories, respectively. Events with an OSSF pair exhibit larger levels of backgroundthan do OSSF0 events.We further classify events with at least one OSSF pair as being “on-Z” if the reconstructedinvariant mass m (cid:96) + (cid:96) − of any of the OSSF dilepton pairings in the event lies in the Z-bosonmass region 75 < m (cid:96) + (cid:96) − <
105 GeV. Since there is considerably less SM background abovethe Z-boson region than below it, we also define “above-Z” and “below-Z” categories, but forthree-lepton events only, where for above-Z (below-Z) events all possible OSSF pairs satisfy m (cid:96) + (cid:96) − >
105 GeV ( m (cid:96) + (cid:96) − <
75 GeV). Additionally, we classify events with four leptons as being“off-Z” if all possible OSSF pairs have m (cid:96) + (cid:96) − values outside the Z-boson mass region.Events with SUSY production of squarks and gluinos may be characterized by a high level ofhadronic activity compared to SM events. We therefore separate events according to whether H T is larger or smaller than 200 GeV. Similarly, we subdivide events into five E missT bins: fourbins of width 50 GeV from 0 to 200 GeV, and a fifth bin with E missT >
200 GeV. For the purposesof presentation in Tables 2 and 3, a coarser E missT binning has been used. The largest background category for trilepton events arises from Z+jets events in which the Zboson decays to a lepton pair while the third lepton candidate is either a misidentified hadronor a genuine lepton from heavy-flavor decay. This background dominates the low- E missT and .2 Misidentified prompt and isolated electrons and muons low- H T channels. As described below (Secs. 5.2, 5.3, and 5.6), this background is evaluatedfrom data.Search channels with τ h candidates suffer from higher background compared to those withonly electrons and muons because sufficiently narrow jets tend to mimic hadronically decaying τ leptons. We measure the background due to misidentified τ h decays from data (Sec. 5.3).Background events containing three or more prompt genuine leptons and a significant level of E missT can arise from SM processes such as WZ+jets or ZZ+jets production if both electroweakbosons decay leptonically. This type of background is referred to as “irreducible” because itscharacteristics are similar to the search signature. We use simulation to estimate the irreduciblebackground (Sec. 5.4). Comparison between data and simulation demonstrates that the E missT distribution is well modeled for processes with genuine E missT , viz., SM model processes withneutrinos [32, 47].Another major source of background is tt production in which each top quark produces a Wboson that decays leptonically, with a third lepton arising from the semileptonic decay of the b-jet daughter of one of the two top quarks. The character of this background differs significantlyfrom the background due to Z+jets events, in which the jets are relatively soft. Simulation isused to evaluate the tt background (Sec. 5.5).Two varieties of photon conversion are relevant to consider. “External” conversion of an on-shell photon in the detector material predominantly results in an e + e − pair, which is eliminatedusing a collection of tracking and kinematic criteria appropriate to the small opening angle ofthe pair. In contrast, the “internal” or “Dalitz” conversion of a virtual photon produces a µ + µ − pair almost as often as an e + e − pair. When an internal conversion is also asymmetric, i.e., whenone of the leptons has a very low p T value, the low p T track can fail to be reconstructed or tosatisfy the selection criteria. Drell–Yan processes accompanied by the high- p T lepton from anasymmetric conversion constitute a significant source of background for trilepton channels. Weestimate this background from data (Sec. 5.6).Remaining backgrounds arise from rare SM processes such as triple-boson production or ttproduction in association with a vector boson and are estimated from simulation.In the following subsections we describe the estimation of main SM backgrounds. Processes such as Z ( → (cid:96) ) + jets and W + W − ( → (cid:96) ) + jets predominantly generate dileptonfinal states. However, rare fluctuations in the hadronization process of an accompanying jet canprovide what appears as a third prompt and isolated lepton, contributing to the backgroundin the trilepton event category. Simulation of rare fragmentation processes can be unreliable.Therefore, we use dilepton data to evaluate this background [11, 48].Consider a dilepton data sample, such as an e + e − sample, that shares attributes such as the E missT and H T values with a trilepton search channel such as e + e − µ . The number of backgroundevents in the e + e − µ channel that originate from e + e − dilepton events is given by the numberof misidentified isolated muons in the e + e − sample. We estimate this number to be the productof the observed number of isolated tracks in the dilepton sample and a proportionality factor f µ between isolated tracks and muons. The factor f µ depends on the selection requirementsof the search channel and, in particular, its heavy-flavor content. Since the impact parame-ters of tracks are generally larger for heavy-flavor decays than for light-flavor (pion and kaon)decays, the average impact parameter value of nonisolated tracks is a good indicator of the heavy-quark content. Therefore, we characterize the variation of f µ from sample to sample asa function of the average impact parameter value of nonisolated tracks in the dilepton sample.The factor f µ is determined in a procedure [11] that considers the numbers of nonisolatedmuons and tracks in the dilepton samples. We use the difference between cross-checks per-formed with ee and µµ samples to evaluate a systematic uncertainty. From a sample of Z ( → e + e − ) + jets events, we determine f µ = ( ± ) %, where the uncertainty is systematic.Using an analogous procedure with a sample of Z ( → µ + µ − ) + jets events, we find f e =( ± ) % for the background from misidentified electron candidates. τ h leptons The probability to misidentify an isolated τ h lepton is determined by calculating an extrapo-lation ratio f τ defined by the number of τ h candidates in the isolation-variable signal region E τ h iso < < E τ h iso < τ h leptons are expected, namely Z+jets events with Z → e + e − or µ + µ − . Theextrapolation ratio is sensitive to the level of jet activity in an event. We study the variation ofthis ratio with respect to H T and the number of jets, using a variety of jet-triggered and dileptonsamples, and assign a systematic uncertainty of 30% based on the observed variation. Usingthis procedure we obtain f τ = ( ± ) %.To estimate the τ h background in a search channel, the number of candidates in the isolationsideband region of the corresponding dilepton sample is multiplied by the extrapolation ratio,analogously to the procedure for f µ described in Sec. 5.2 for the background from misidentifiedelectrons and muons. WZ and ZZ production The irreducible background, from WZ+jets and ZZ+jets events where both electroweak bosonsdecay leptonically, is evaluated using samples of simulated events corrected for the measuredlepton reconstruction efficiency and E missT resolution. The simulated WZ and ZZ distributionsare normalized to corresponding measured results obtained from WZ- and ZZ-dominated datacontrol samples, defined by selecting events with on-Z, low- H T , and 50 < E missT <
100 GeVrequirements, or two-on-Z, low- H T , and E missT <
50 GeV requirements, respectively. The nor-malization factors have statistical uncertainties of 6% and 12%, again respectively.The E missT distribution is examined in individual two-dimensional bins of H T and the numberof reconstructed vertices in the event. In an individual bin, the x and y components of E missT are found to be approximately Gaussian. The E missT resolution is adversely affected by bothpileup and jet activity, but in different ways. The effects of pileup are stochastic, affecting theGaussian widths of the distributions, while jet activity affects the tails. We apply smearingfactors to the Gaussian widths of the simulated events so that the E missT resolution matches thatof the data. The corrections to the widths vary from a few percent to as high as around 25%depending on the bin. The effects of jet activity are accounted for in the evaluation of systematicuncertainties, which are determined by varying the smearing factors and assessing the level ofmigration between different bins of E missT and H T .For purposes of validation, Fig. 1 shows the distribution of E missT for an on-Z, low- H T , trilep-ton (eee, ee µ , e µµ , and µµµ ), WZ-dominated data control sample defined by 75 < m (cid:96) + (cid:96) − <
105 GeV, H T <
200 GeV, and 50 < M T <
100 GeV, where M T is the transverse mass [49] formedfrom the E missT vector and the lepton not belonging to the OSSF pair. The results are shown incomparison to simulated results that include the above-mentioned corrections. .5 Background from tt production (GeV) Tmiss E E v en t s / G e V CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s DataBkg uncertaintyMisidentifiedtt Wtt ZttWZZZ
Figure 1: Distribution of E missT for a WZ-enriched data control sample, in comparison to the re-sult from simulation. “Misidentified” refers to SM background from Drell–Yan events, misiden-tified τ h decays, and internal photon conversions. The simulation is normalized to a controlregion in data. tt production The background from tt events is evaluated from simulation, with corrections applied for lep-ton efficiencies and E missT resolution as described in Sec. 5.4. Figure 2 shows the distributions of E missT and H T for the data and corrected simulation in a tt-enriched control sample selected byrequiring events to contain an opposite-sign e µ pair and at least one tagged b jet. (GeV) Tmiss E
50 100 150 200 250 300 350 400 450 500 E v en t s / G e V -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s DataBkg uncertaintytt Wtt ZttWZZZ (GeV) T H
100 200 300 400 500 600 700 800 900 1000 E v en t s / G e V -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s DataBkg uncertaintytt Wtt ZttWZZZ
Figure 2: Distribution of (left) E missT and (right) H T for a tt-enriched data control sample, incomparison to the result from simulation. The background from photon conversions is evaluated from data by selecting a low- E missT , low- H T control region defined by E missT <
30 GeV and H T <
200 GeV and measuring the ratio of thenumber of events with | m (cid:96) + (cid:96) − (cid:96) ( (cid:48) ) ± − m Z | <
15 GeV to those with | m (cid:96) + (cid:96) − γ − m Z | <
15 GeV. Wefind a result of ( ± ) % for electrons and ( ± ) % for muons, where the uncertaintyis statistical. We multiply these factors by the measured (cid:96) + (cid:96) − γ rates in the signal regions toestimate the rate of photon-conversion background events in these regions, with a systematicuncertainty of 50%. The evaluation of systematic uncertainties for the SM background is partially discussed in theprevious section. In this section, we discuss additional sources of uncertainty, both for thebackground estimates and the signal predictions.Simulated signal and background samples are subject to uncertainties from the trigger, lepton-identification, and isolation requirements. The latter two uncertainties are combined into asingle term that is approximately 1.5% for leptons with p T >
20 GeV. The trigger efficiencyuncertainties are approximately 5%. Uncertainties associated with the jet energy scale [36],b-jet tagging efficiency [38], E missT resolution, and luminosity [50] affect signal efficiencies aswell as background estimates determined from simulation. The signal efficiencies are subjectto an additional uncertainty, from the ISR modeling [23]. Uncertainties in the cross sectioncalculations affect the signal samples and simulation-derived background estimates, with theexception of the background from WZ and ZZ production, whose normalization is determinedfrom data.We assign a 50% uncertainty to the estimate of the misidentified lepton background arisingfrom tt production, which is a combination of the uncertainty attributed to the cross sectionand an uncertainty derived from the level of agreement between data and simulation for thedistribution of the isolation variable.The total systematic uncertainty per channel varies between 3% and 40%. Table 1 list represen-tative values for some of the individual terms.Table 1: Typical values for systematic uncertainties.Source of uncertainty Magnitude (%)Luminosity 2.6ISR modeling 0–5 E missT resolution for WZ events ∼ τ h -lepton ID/isolation at 10 (100) GeV 2 (1.1)Trigger efficiency 5tt cross section/isolation variable 50 Table 2 presents the results of the searches for events with four or more leptons, and Table 3the results for exactly three leptons. The observed numbers of events are seen to be in overallagreement with the SM expectations.Three excesses in the data relative to the SM estimates are worth noting in Table 2. All con-cern events in the OSSF1, off-Z category with one τ h -lepton candidate, no tagged b jet, and H T <
200 GeV. Specifically, we observe 15, 4, and 3 events for 0 < E missT <
50 GeV, 50 < E missT <
100 GeV, and E missT >
100 GeV, respectively, when only 7.5 ± ± ± ± E missT range. We de-termine the single-measurement probability to observe 22 or more events when the expectednumber is 10.1 ± account for the 64 independent channels of the analysis, the probability to observe such a fluc-tuation increases to about 50%. Alternatively, the joint probability to observe at least as largean excess for all three channels considered individually is about 5%. We account for systematicuncertainties and their correlations when evaluating these probabilities.Table 2: Observed (Obs.) numbers of events with four or more leptons in comparison withthe expected (Exp.) numbers of SM background events. “On-Z” refers to events with at leastone e + e − or µ + µ − (OSSF) pair with dilepton mass between 75 and 105 GeV, while “Off-Z”refers to events with one or two OSSF pairs, none of which fall in this mass range. The OSSF n designation refers to the number of e + e − and µ + µ − pairs in the event, as explained in the text.Search channels binned in E missT have been combined into coarse E missT bins for the purposes ofpresentation. All uncertainties include both the statistical and systematic terms. The channelmarked with an asterisk is used for normalization purposes and is excluded from the search. ≥ m (cid:96) + (cid:96) − E missT N τ h = N b = N τ h = N b = N τ h = N b ≥ N τ h = N b ≥ H T >
200 GeV (GeV) Obs. Exp. Obs. Exp. Obs. Exp. Obs. Exp.OSSF0 — (100, ∞ ) 0 0.01 + − + − + − ± + − + − + − ± + − + − + − ± ∞ ) 0 0.01 + − ± ± ± ∞ ) 1 0.10 ± ± ± ± ± ± ± ± ± ± ± ± + − ± + − ± ± ± ± ± ∞ ) 0 0.01 + − — — 0 0.01 + − — —OSSF2 On-Z (100, ∞ ) 1 0.15 + − — — 0 0.34 ± ± ± ± ± ± ± ± ± ≥ m (cid:96) + (cid:96) − E missT N τ h = N b = N τ h = N b = N τ h = N b ≥ N τ h = N b ≥ H T <
200 GeV (GeV) Obs. Exp. Obs. Exp. Obs. Exp. Obs. Exp.OSSF0 — (100, ∞ ) 0 0.11 ± ± + − ± + − ± + − ± + − ± + − ± ∞ ) 0 0.06 ± ± + − ± ∞ ) 1 0.50 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
10 1 0.31 ± ± ∞ ) 0 0.04 ± ± ∞ ) 0 0.34 ± ± ± + − — —OSSF2 On-Z (50, 100) 4 3.9 ± ± ± ± ±
34 — — 4 2.9 ± We consider five new-physics scenarios that appear in the framework of the minimal super-symmetric standard model (MSSM) [4, 5]. They involve sleptons (including staus), bottom andtop squarks, higgsinos, gravitinos, neutralinos, and charginos, where higgsinos are the super-partners of the Higgs bosons, the gravitino (cid:101)
G is the superpartner of the graviton, while neu-tralinos (charginos) are mixtures of the superpartners of neutral (charged) electroweak vector Table 3: Observed (Obs.) numbers of events with exactly three leptons in comparison with theexpected (Exp.) numbers of SM background events. “On-Z” refers to events with an e + e − or µ + µ − (OSSF) pair with dilepton mass between 75 and 105 GeV, while “Above-Z” and “Below-Z” refer to events with an OSSF pair with mass above 105 GeV or below 75 GeV, respectively.The OSSF n designation refers to the number of e + e − and µ + µ − pairs in the event, as explainedin the text. Search channels binned in E missT have been combined into coarse E missT bins for thepurposes of presentation. All uncertainties include both the statistical and systematic terms.The channels marked with an asterisk are used for normalization purposes and are excludedfrom the search. m (cid:96) + (cid:96) − E missT N τ h = N b = N τ h = N b = N τ h = N b ≥ N τ h = N b ≥ H T >
200 GeV (GeV) Obs. Exp. Obs. Exp. Obs. Exp. Obs. Exp.OSSF0 — (100, ∞ ) 5 3.7 ± ±
14 1 5.5 ± ± ± ±
16 8 7.7 ± ± ± ±
10 1 3.6 ± ± ∞ ) 5 3.6 ± ± ± ± ∞ ) 7 9.7 ± ± ± ± ∞ ) 39 61 ±
23 17 15.0 ± ± ± ± ± ± ± ± ± ± ± ±
32 70 50 ±
11 22 22.0 ± ± ± ± ± ± ± ±
23 5 10.0 ± ± ±
41 542 540 ±
160 31 32.0 ± ±
193 leptons m (cid:96) + (cid:96) − E missT N τ h = N b = N τ h = N b = N τ h = N b ≥ N τ h = N b ≥ H T <
200 GeV (GeV) Obs. Exp. Obs. Exp. Obs. Exp. Obs. Exp.OSSF0 — (100, ∞ ) 7 11.0 ± ±
54 13 10.0 ± ± ±
15 406 402 ±
152 29 26 ±
13 269 298 ± ±
11 910 1035 ±
255 29 23 ±
10 237 240 ± ∞ ) 18 13.0 ± ±
18 10 6.5 ± ± ∞ ) 21 24 ± ±
25 14 20 ±
10 42 54 ± ∞ ) 150 150 ±
26 39 48 ±
13 15 14.0 ± ± ± ±
48 20 18 ± ± ±
27 353 360 ±
92 48 48 ±
23 140 133 ± ±
120 1276 1200 ±
310 56 47 ±
13 81 75 ± ±
35 1676 1900 ±
540 17 18.0 ± ± ±
87 9939 9000 ± ±
11 226 228 ± ±
670 *50188 50000 ± ±
24 906 925 ± and Higgs bosons. The first three scenarios feature the gravitino as the LSP, while the lightestneutralino (cid:101) χ is the LSP for the other two scenarios. The first and last two scenarios proceedthrough the production of third-generation squarks, yielding final states rich in heavy-flavorjets. Taken together, these five scenarios present a wide spectrum of multilepton signatures.Our search results lack striking departures from the SM, and we set limits on the productioncross sections of the five scenarios. The limits are determined using the observed numbers ofevents, the SM background estimates, and the predicted event yields. For each scenario, weorder the search channels by their expected sensitivities and then combine channels, startingwith the most sensitive one. For ease of computation and with a negligible loss in overallsensitivity, we do not consider channels once the number of signal events integrated over theretained channels reaches 90% of the total. The list of selected channels thus depends notonly on the scenario considered, but also on the assumed superpartner masses and branchingfractions.We set 95% confidence level (CL) upper limits on the signal parameters and cross sectionsusing the modified frequentest CL s method with the LHC-style test statistic [51–53]. Lognormalnuisance-parameter distributions are used to account for uncertainties. .1 Natural higgsino NLSP scenario We first present a supersymmetric scenario in which the (cid:101) χ neutralino is a higgsino that formsthe next-to-LSP (NLSP) state [21]. We refer to this scenario as the “natural higgsino NLSP” sce-nario. This scenario arises in gauge-mediated SUSY-breaking (GMSB) models [54]. Productionproceeds through the right-handed top-antitop squark pair (cid:101) t R (cid:101) t ∗ R , with the subsequent decays (cid:101) t R → b (cid:101) χ + or (cid:101) t R → t (cid:101) χ i ( i =
1, 2 ) , where (cid:101) χ + is the lightest chargino and (cid:101) χ the second-lightestneutralino (both taken to be higgsinos), with the (cid:101) q ∗ state the charge conjugate of the (cid:101) q state.The (cid:101) χ + and (cid:101) χ states each decay to the (cid:101) χ and SM particles. Figure 3 shows an event diagramand a schematic mass spectrum. The last step in each of the two top-squark decay chains is thedecay (cid:101) χ → H (cid:101) G or Z (cid:101)
G, yielding an HH, HZ, or ZZ configuration, with E missT from the unde-tected gravitino. Note that we assume H (cid:101) G and Z (cid:101)
G to be the only two possible decay modes forthe (cid:101) χ higgsino [54].Beyond the top-squark pair production diagram of Fig. 3, the natural higgsino NLSP scenarioalso encompasses direct higgsino pair production, in which the (cid:101) χ + and (cid:101) χ − states of Fig. 3 (plusother di-higgsino states) are produced through electroweak interactions, leading to the sameHH, HZ, and ZZ configuration as in Fig. 3, but with less jet activity [54]. Our search results arealso sensitive to this scenario.Of the five new-physics scenarios we examine, the natural higgsino NLSP scenario exhibits thelargest range with respect to its population of the different search channels. The channels withhighest sensitivity are those that require b jets, and, for the decays through the HZ and ZZstates, the channels with on-Z and off-Z requirements. P P ˜ t ∗ R ˜ t R ˜ χ − ˜ χ +1 ˜ χ ˜ χ b (jet, ‘ )(jet, ν )˜ G H,ZH,Z˜ G (jet, ν )(jet, ‘ )b !" +,-.$ &'()"* =(0%% &'()"* % A% :(.0'(/%A"BB2" C%.%
Figure 3: Event diagram and a schematic superpartner mass spectrum for the GMSB naturalhiggsino NLSP scenario, with (cid:101) χ ± ( (cid:101) χ ) the lightest chargino (neutralino), H the lightest MSSMHiggs boson, and (cid:101) G a gravitino. Particles in parentheses in the event diagram have a soft p T spectrum.The natural higgsino NLSP scenario is complex because the higgsino can decay to either aZ or Higgs boson, while the Higgs boson has many decay modes that lead to leptons. Weconsider seven decay channels for the HH configuration: WW ∗ WW ∗ , ZZ ∗ ZZ ∗ , ττττ , WW ∗ ZZ ∗ ,WW ∗ ττ , ZZ ∗ ττ , and ZZ ∗ bb, and three decay channels for the HZ configuration: WW ∗ Z, ZZ ∗ Z,and ττ Z, where W ∗ and Z ∗ indicate off-shell vector bosons.Signal events for the natural higgsino NLSP scenario are generated using M AD G RAPH , as de-scribed in Sec. 3. The (cid:101) χ and (cid:101) χ higgsinos are assigned masses 5 GeV below and above the massof the (cid:101) χ ± higgsino, respectively, while the gravitino is assumed to be massless. In the limit of no mixing between higgsinos and gauginos, the light neutralinos and charginos become de-generate [54]. The 5 GeV splitting is representative of proximity to this limit. We generatesignal events for a range of (cid:101) t R and (cid:101) χ ± mass values. Cross sections for both the strong and elec-troweak production processes are assigned an uncertainty of 20%, which also accounts for theuncertainties associated with the PDFs and with the renormalization and factorization scales.Figure 4 shows the excluded regions in the plane of m (cid:101) χ ± versus m (cid:101) t . The results are shown forseveral choices for the (cid:101) χ → H (cid:101) G branching fraction. One-dimensional exclusion plots withfixed choices for the branching fraction and chargino mass are shown in Fig. 5. The searchsensitivity is larger for lower chargino masses because of the larger cross section. There is lesssensitivity for the Higgs-boson-dominated mode in comparison with the Z-boson-dominatedmode. Figure 6 shows the results as a function of the (cid:101) χ → H (cid:101) G branching fraction and the topsquark mass for different chargino masses. (GeV) t~ m
200 300 400 500 600 700 800 ( G e V ) – c~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s Natural Higgsino NLSP (GMSB) ) = 0.5, strong and weak productionG~ Z fi c~ ( B ) = G~ H fi c~ ( B Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m (GeV) t~ m
200 250 300 350 400 450 500 ( G e V ) – c~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s Natural Higgsino NLSP (GMSB) ) = 1, strong and weak productionG~ H fi c~ ( B Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m (GeV) t~ m
200 300 400 500 600 700 800 ( G e V ) – c~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s Natural Higgsino NLSP (GMSB) ) = 1, strong and weak productionG~ Z fi c~ ( B Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m Figure 4: The 95% confidence level upper limits in the top squark versus chargino mass plane,for the natural higgsino NLSP scenario with the following (cid:101) χ branching fractions: B ( (cid:101) χ → H (cid:101) G ) = B ( (cid:101) χ → Z (cid:101) G ) = B ( (cid:101) χ → H (cid:101) G ) = B ( (cid:101) χ → Z (cid:101) G ) = We next consider the slepton co-NLSP scenario [21, 53], in which mass-degenerate right-handedsleptons (cid:101) (cid:96) R (selectron, smuon, stau) serve together as the NLSP. This scenario arises in a broadclass of GMSB models and can lead to a multilepton final state [55–58]. The process proceedsprimarily through gluino (cid:101) g and squark (cid:101) q pair production [59]. An event diagram and schematic .2 Slepton co-NLSP scenario (GeV) t~ m
200 300 400 500 600 700 800 ( pb ) B · s -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m Natural Higgsino NLSP (GMSB) = 150 GeV – c~ ) = 0.5, mG~ Z fi c~ ( B ) = G~ H fi c~ ( B Observed 95% CL limitsExpected 95% CL limits s – Expected Theory (NLO+NLL)Theoretical uncertainty (GeV) t~ m
200 300 400 500 600 700 800 ( pb ) B · s -2 -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m unph ys i c a l Natural Higgsino NLSP (GMSB) = 350 GeV – c~ ) = 0.5, mG~ Z fi c~ ( B ) = G~ H fi c~ ( B Observed 95% CL limitsExpected 95% CL limits s – Expected Theory (NLO+NLL)Theoretical uncertainty (GeV) t~ m
200 300 400 500 600 700 800 ( pb ) B · s -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m = 150 GeV – c~ ) = 1, mG~ H fi c~ ( B , Natural Higgsino NLSP (GMSB)
Observed 95% CL limitsExpected 95% CL limits s – Expected s – Expected Theory (NLO+NLL)Theoretical uncertainty (GeV) t~ m
200 300 400 500 600 700 800 ( pb ) B · s -2 -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m unph ys i c a l Natural Higgsino NLSP (GMSB) = 350 GeV – c~ ) = 1, mG~ H fi c~ ( B Observed 95% CL limitsexpected 95% CL limits s – Expected s – Expected Theory (NLO+NLL)Theoretical uncertainty (GeV) t~ m
200 300 400 500 600 700 800 ( pb ) B · s -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m Natural Higgsino NLSP (GMSB) = 150 GeV – c~ ) = 1, mG~ Z fi c~ ( B Observed 95% CL limitsExpected 95% CL limits s – Expected Theory (NLO+NLL)Theoretical uncertainty (GeV) t~ m
200 300 400 500 600 700 800 ( pb ) B · s -2 -1 CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m unph ys i c a l Natural Higgsino NLSP (GMSB) = 350 GeV – c~ ) = 1, mG~ Z fi c~ ( B Observed 95% CL limitsExpected 95% CL limits s – Expected Theory (NLO+NLL)Theoretical uncertainty
Figure 5: The 95% confidence level upper limits on cross section times branching fraction B ,for the natural higgsino NLSP scenario for B ( (cid:101) χ → H (cid:101) G ) = B ( (cid:101) χ → Z (cid:101) G ) = B ( (cid:101) χ → H (cid:101) G ) = B ( (cid:101) χ → Z (cid:101) G ) = (cid:101) χ neutralino is taken to be a bino, the superpartnerof the B gauge boson. The bino decays to a lepton and the NLSP, while the NLSP decays to thegravitino LSP and an additional lepton. Depending on the mass spectrum, the events can havelarge H T . Channels with no tagged b jets and off-Z OSSF pairs exhibit the largest sensitivity forthis scenario.Beyond production through squarks and gluinos, production through chargino-neutralino orright-handed slepton pairs is possible. The decay of each parent eventually leads to a bino (cid:101) χ , which decays as shown in Fig. 7, leading to a final state with multileptons and E missT as forthe strong-production process. The relative importance of the strong- and weak-production (GeV) t~ m
200 300 400 500 600 700 800 ) G ~ H fi c~ ( B CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m = 150 GeV, strong and weak production – c~ Natural Higgsino NLSP (GMSB)
Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected (GeV) t~ m
200 300 400 500 600 700 800 ) G ~ H fi c~ ( B CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m unph ys i c a l = 250 GeV, strong and weak production – c~ Natural Higgsino NLSP (GMSB)
Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected (GeV) t~ m
200 300 400 500 600 700 800 ) G ~ H fi c~ ( B CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s + 5 GeV – c~ = m c~ m 5 GeV - – c~ = m c~ m unph ys i c a l = 350 GeV, strong and weak production – c~ Natural Higgsino NLSP (GMSB)
Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected
Figure 6: The 95% confidence level upper limits on the branching fraction B ( (cid:101) χ → H (cid:101) G ) forthe natural higgsino NLSP scenario with fixed charged higgsino mass of 150 GeV (upper left),250 GeV (upper right), and 350 GeV (bottom) assuming B ( (cid:101) χ → H (cid:101) G ) + B ( (cid:101) χ → Z (cid:101) G ) = P P ˜ q, ˜ g ˜ q, ˜ g ˜ χ ˜ χ ˜ ‘ R ˜ ‘ R jet(s) ‘ ‘ ˜ G ˜ G‘‘ jet(s)1 !" +,-.$ &'()"* =(0%% &'()"* % A"BB2%%% :(.0'(/%A"BB2" C96$2$
Figure 7: Event diagram and a schematic superpartner mass spectrum for the GMSB sleptonco-NLSP scenario.mechanisms depends on the values of the superpartner masses.Signal events for the slepton co-NLSP scenario are generated using the
PYTHIA generator. Thesuperpartner mass spectrum is parametrized in terms of the masses of the (cid:101) χ ± chargino and thegluino. The remaining superpartner masses are chosen to be m (cid:101) (cid:96) R = m (cid:101) χ ± , m (cid:101) χ = m (cid:101) χ ± , .3 The stau-(N)NLSP scenario m (cid:101) (cid:96) L = m (cid:101) χ ± , and m (cid:101) q = m (cid:101) g , with no mixing of the left- and right-handed slepton andsquark components, and with the higgsino masses so large that their contributions are negli-gible. The cross sections are calculated at NLO using K-factors from PROSPINO [60] and areassigned a 30% theoretical uncertainty, taking into account cross section, scale, and PDF uncer-tainties.The 95% CL exclusions limits for the slepton co-NLSP scenario are shown in Fig. 8 (left) as afunction of the gluino and chargino masses. In the region dominated by strong superpartnerproduction, the exclusion curve asymptotically approaches a horizontal plateau, while it tendstowards a vertical line in the region dominated by weak superpartner production. (GeV) – c~ m
800 1000 1200 1400 1600 1800 ( G e V ) g ~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s g~ = 0.8m q~ m – c~ = 0.5m c~ m – c~ = 0.8 (0.3) m L(R) l~ m Slepton co-NLSP (GMSB)
Observed 95% CL limitsTheoretical uncertainty (NLO)Expected 95% CL limits experimental s – Expected (GeV) m ~ = m e~ m
50 100 150 200 250 300 350 400 450 500 ( G e V ) t ~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s Stau-NLSP and Stau-NNLSP
Observed 95% CL limitsTheoretical uncertainty (NLO)Expected 95% CL limits experimental s – Expected experimental s – Expected experimental s Expected -3
Figure 8: The 95% confidence level upper limits for the slepton co-NLSP model in the gluinoversus chargino mass plane (left) and for the stau-(N)NLSP scenarios in the stau versusdegenerate-smuon and -selectron mass plane (right). The region to the left and below the con-tours is excluded.
In the stau-NLSP scenario, the right-handed stau lepton is the NLSP. This scenario arises formoderate to large values of the MSSM parameter tan β [4, 5]. Mass-degenerate right-handedselectrons and smuons decay to the stau through the three-body processes (cid:101) e R → (cid:101) τ R τ e and (cid:101) µ R → (cid:101) τ R τµ . The stau decays as (cid:101) τ R → (cid:101) G τ . Pair production of selectrons or smuons leads to amultilepton final state dominated by τ leptons. A diagram and schematic mass spectrum areshown in Fig. 9.Besides the stau-NLSP scenario, we also consider the stau-NNLSP scenario in which mass-degenerate right-handed selectrons and smuons are co-NLSPs, while the right-handed stau isthe next-to-next-to-lightest SUSY particle (NNLSP). The process proceeds via electroweak pairproduction of staus. The staus decay to the NLSP and a τ lepton. The NLSPs decay to a τ lepton and gravitino.The search channels most sensitive to the stau-(N)NLSP scenarios contain τ h leptons, no taggedb jets, off-Z OSSF pairs, and large E missT . Signal events for the stau-(N)NLSP model are gener-ated using PYTHIA [45]. The cross sections are normalized to NLO calculations using
PROSPINO [60] and are assigned a 30% theoretical uncertainty.The 95% CL exclusion limits for the stau-(N)NLSP scenario are shown in Fig. 8 (bottom). Whenthe mass difference between the stau and the other sleptons is small, the leptons are soft. Thisresults in low signal efficiency, which causes the exclusion contour to become nearly parallel tothe diagonal for points near the diagonal. The difference between the expected and observedlimits in the region below the diagonal is driven by the excesses observed between the data P P ˜ ‘ − R ˜ ‘ + R ˜ τ + R ˜ τ − R ‘ − τ − τ + ˜ G ˜ Gτ − τ + ‘ + !" +,-.$ &'()"* =(0%% &'()"* % A"BB2%%% :(.0'(/%A"BB2" C96$2$
Figure 9: Event diagram and a schematic superpartner mass spectrum for the GMSB stau-(N)NLSP scenario.and SM estimates in the four-or-more lepton, OSSF1, off-Z, τ h channels without b jets, noted inSec. 7. In the T1tttt simplified model spectra (SMS) scenario [58, 61, 62], pair-produced gluinos eachdecay to a top quark and a virtual top squark. The virtual top squark decays to a top quarkand the LSP, where the LSP is the lightest neutralino. Thus each gluino undergoes an effectivethree-body decay to two top quarks and the LSP, yielding four top quarks in the final state.Each top quark can potentially yield a b jet and a leptonically decaying W boson, leading to amultilepton final state with b jets and E missT . Because of the large number of jets, the H T valuecan be quite large. An event diagram and schematic mass spectrum are shown in Fig. 10. P P ˜ g ˜ g ¯ t t ˜ χ ˜ χ ¯ tt !" ' -.//' '/'' 01&/&2'34,+5$%&' -6/77' () ' Figure 10: Event diagram and a schematic superpartner mass spectrum for the SMS T1ttttscenario.The presence of four top quarks in the final state results in four b quarks and four W bosons.The W-boson decays can produce up to four leptons with large E missT . The SM backgroundis significantly reduced by requiring the presence of a b jet. This requirement represents animprovement with respect to our analysis of the 7 TeV data [11].Signal events for the T1tttt scenario are generated using M AD G RAPH . The cross sections arecalculated at the NLO plus next-to-leading-logarithm (NLL) level [59, 63–66] with uncertaintiesthat vary between 23% and 27% [67].The 95% CL exclusion limits in the gluino versus LSP mass plane are shown in Fig. 11 (left).We exclude gluinos with mass values below 1 TeV over much of this plane. .5 Third-generation SMS scenario T6ttWW (GeV) g~ m
700 800 900 1000 1100 1200 ( G e V ) c~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s c~ t t fi g~, g~g~ fi , pp T1tttt
Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected (GeV) b~ m
350 400 450 500 550 600 650 700 ( G e V ) – c~ m CMS -1 = 19.5 fb t d L (cid:242) = 8 TeV, s c~ tW fi b~*, b~ b~ fi , pp T6ttWW
Observed 95% CL limitsTheoretical uncertainty (NLO+NLL)Expected 95% CL limits experimental s – Expected = 50 GeV c~ m Figure 11: 95% confidence level upper limits for the T1tttt scenario in the LSP versus gluinomass plane (left) and for the T6ttWW scenario in the chargino versus bottom-squark mass plane(right) are shown. Masses to the left and below the contours are excluded.
In the T6ttWW SMS scenario, we search for SUSY signals with direct bottom-squark pair pro-duction [62, 68]. An event diagram and schematic mass spectrum are shown in Fig. 12. Thebottom squark decays as (cid:101) b → t (cid:101) χ − , while the chargino decays as (cid:101) χ − → W − (cid:101) χ . This scenariopopulates channels with tagged b jets. P P ˜ b ˜ b ∗ χ − W − χ + W + t ˜ χ ˜ χ ¯ t !" ' -.//' '/'' 01&/&2'34,+5$%&' -6/77' () ' Figure 12: Event diagram and a schematic superpartner mass spectrum for the SMS T6ttWWscenario.For simplicity, we consider on-shell charginos. The W boson from the chargino decay can beeither on- or off-shell. Signal events are generated using M AD G RAPH with normalization ofthe cross section performed to NLO+NLL [59, 63–66]. The uncertainty of the cross sectioncalculation is 30% [67].Figure 11 (bottom) shows the exclusion limits for the T6ttWW scenario in the chargino versusbottom-squark mass plane. The mass of the (cid:101) χ is assumed to be 50 GeV. We exclude bottomsquarks with mass values less than 550 GeV. This result complements our study of this samescenario performed using same-sign dilepton events and obtains similar conclusions [22]. t → cH Beyond the SUSY scenarios examined in Sec. 8, we interpret our results in the context of theflavor-changing decay of a top quark to a Higgs boson and a charm quark. Although not t → cH forbidden in the SM, the SM branching fraction is predicted to be extremely small (10 − –10 − [9, 10]), due to suppression both by the Glashow–Iliopoulos–Maiani mechanism [69]and by the Cabibbo–Kobayashi–Maskawa quark-mixing matrix [70] factor. Observation of thet → cH transition can therefore provide evidence for BSM physics, i.e., for non-SM particlesproduced virtually in loops. In this sense the t → cH transition plays a complementary role toSUSY searches compared to the direct superpartner production scenarios considered in Sec. 8.In addition, the t → cH decay directly probes the flavor-violating couplings of the Higgs bo-son to the top quark. Since up-type quark-flavor violation is less constrained than down-typequark-flavor violation [71], exploration of this issue is of general interest.The production of a tt pair followed by the decay of one top quark to a cH state and the otherto a bW state can yield a multilepton signature, especially if the Higgs boson decays throughone of the following channels: • H → WW ∗ → (cid:96) ν (cid:96) ν , • H → ττ , or • H → ZZ ∗ → jj (cid:96)(cid:96) , νν (cid:96)(cid:96) , (cid:96)(cid:96)(cid:96)(cid:96) ,where j refers to a jet. If the t → bW decay also produces a lepton, there can be up to fiveleptons in an event.To simulate signal events, we generate a tt sample in which one top quark decays to cH andthe other to bW. We assume m H =
126 GeV [72] and that the Higgs boson has SM branchingfractions. We only consider the decay modes listed above because the contributions of otherHiggs boson decay modes to the multilepton final state are found to be negligible. Signal eventsare generated using M AD G RAPH , with normalization performed at the next-to-next-to-leadingorder [73].The signal events predominantly populate channels with three leptons, a tagged b jet, no τ h -lepton candidate, and an OSSF off-Z pair or no OSSF pair. The most sensitive channels arelisted in Table 4. The main source of SM background arises from tt production. The observednumbers of events are seen to be in agreement with the SM expectations to within the uncer-tainties.Table 4: The ten most sensitive signal regions for the t → cH process, along with the number ofobserved (Obs.), background (Exp.), and expected signal (Sig.) events, assuming B ( t → cH ) = E missT , H T , number of tagged b jets or τ h candidates, and, if an OSSF pair ispresent, its invariant mass with respect to the Z-boson mass window.OSSF pair N τ h E missT (GeV) H T (GeV) N b Obs. Exp. Sig.Below-Z 0 50–100 0–200 ≥ ±
23 9.5 ± ≥ ±
13 5.9 ± ≥ ±
11 5.9 ± ≥ ±
10 4.3 ± > ≥ ± ± > ≥ ± ± ±
27 9.7 ± ≥ ±
113 13.1 ± ±
15 4.3 ± ≥ ± ± Using the same limit-setting procedure as in Sec. 8, we obtain a 95% CL upper limit on thebranching fraction of B ( t → cH ) < ( + − ) %. Theuncertainties include both the statistical and systematic terms. The observed limit correspondsto a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, λ Htc and λ Hct , respectively, of (cid:113) | λ Htc | + | λ Hct | < (cid:113) | λ Htc | + | λ Hct | < → WW ∗ → (cid:96) ν (cid:96) ν mode dominates the overall result.Table 5: Comparison of the observed (Obs.) and median expected (Exp.) 95% CL upper lim-its on B ( t → cH ) from individual Higgs boson decay modes, along with their one standarddeviation ( σ ) uncertainties. The uncertainties include both statistical and systematic terms.Higgs boson decay mode Upper limits on B ( t → cH ) Obs. Exp. 1 σ range B ( H → WW ∗ ) = B ( H → ττ ) = B ( H → ZZ ∗ ) =
10 Summary
We have performed a search for physics beyond the standard model based on events with threeor more leptons, where one of these leptons can be a hadronically decaying τ lepton. We searchin channels with e + e − or µ + µ − pairs that are either consistent or inconsistent with Z bosondecay, in channels without such a pair, in channels with or without a hadronically decaying τ -lepton candidate, in channels with and without a tagged bottom-quark jet, in events withand without a large level of jet activity (measured with the scalar sum of jet p T values), andin different bins of missing transverse energy. We find no significant excesses compared to theexpectations from standard model processes. The search is performed separately for eventswith exactly three leptons and with four or more leptons.We examine a broad class of supersymmetric scenarios that, taken together, populate a broadspectrum of multilepton final states. Compared to previous results, we probe new regions ofthe parameter space for the natural higgsino next-to-lightest supersymmetric particle (NLSP),slepton co-NLSP, and stau-(N)NLSP scenarios, where (N)NLSP denotes the (next-to-)next-to-lightest-supersymmetric particle. In addition, we investigate scenarios with gluino pair pro-duction followed by gluino decay to a top-antitop pair and the lightest supersymmetric par-ticle, and direct bottom-squark pair production. Cross section upper limits at 95% confidencelevel are presented for all these scenarios.We further explore rare transitions of the top quark to a charm quark and a Higgs boson, t → cH. We set a 95% confidence level upper limit of 1.3% on the branching fraction of this decay,which corresponds to an upper bound (cid:113) | λ Htc | + | λ Hct | <
10 Summary
Acknowledgements
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: the Austrian Federal Min-istry of Science, Research and Economy and the Austrian Science Fund; the Belgian Fonds dela Recherche Scientifique, and Fonds voor Wetenschappelijk Onderzoek; the Brazilian Fund-ing Agencies (CNPq, CAPES, FAPERJ, and FAPESP); the Bulgarian Ministry of Education andScience; CERN; the Chinese Academy of Sciences, Ministry of Science and Technology, andNational Natural Science Foundation of China; the Colombian Funding Agency (COLCIEN-CIAS); the Croatian Ministry of Science, Education and Sport, and the Croatian Science Foun-dation; the Research Promotion Foundation, Cyprus; the Ministry of Education and Research,Recurrent Financing Contract No. SF0690030s09 and European Regional Development Fund,Estonia; the Academy of Finland, Finnish Ministry of Education and Culture, and HelsinkiInstitute of Physics; the Institut National de Physique Nucl´eaire et de Physique des Partic-ules / CNRS, and Commissariat `a l’ ´Energie Atomique et aux ´Energies Alternatives / CEA,France; the Bundesministerium f ¨ur Bildung und Forschung, Deutsche Forschungsgemeinschaft,and Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany; the General Secretariatfor Research and Technology, Greece; the National Scientific Research Foundation, and Na-tional Innovation Office, Hungary; the Department of Atomic Energy and the Department ofScience and Technology, India; the Institute for Studies in Theoretical Physics and Mathematics,Iran; the Science Foundation, Ireland; the Istituto Nazionale di Fisica Nucleare, Italy; the Ko-rean Ministry of Education, Science and Technology and the World Class University program ofNRF, Republic of Korea; the Lithuanian Academy of Sciences; the Ministry of Education, andUniversity of Malaya (Malaysia); the Mexican Funding Agencies (CINVESTAV, CONACYT,SEP, and UASLP-FAI); the Ministry of Business, Innovation and Employment, New Zealand;the Pakistan Atomic Energy Commission; the Ministry of Science and Higher Education andthe National Science Centre, Poland; the Fundac¸ ˜ao para a Ciˆencia e a Tecnologia, Portugal;JINR, Dubna; the Ministry of Education and Science of the Russian Federation, the FederalAgency of Atomic Energy of the Russian Federation, Russian Academy of Sciences, and theRussian Foundation for Basic Research; the Ministry of Education, Science and Technologi-cal Development of Serbia; the Secretar´ıa de Estado de Investigaci ´on, Desarrollo e Innovaci ´onand Programa Consolider-Ingenio 2010, Spain; the Swiss Funding Agencies (ETH Board, ETHZurich, PSI, SNF, UniZH, Canton Zurich, and SER); the Ministry of Science and Technology,Taipei; the Thailand Center of Excellence in Physics, the Institute for the Promotion of Teach-ing Science and Technology of Thailand, Special Task Force for Activating Research and theNational Science and Technology Development Agency of Thailand; the Scientific and Techni-cal Research Council of Turkey, and Turkish Atomic Energy Authority; the National Academyof Sciences of Ukraine, and State Fund for Fundamental Researches, Ukraine; the Science andTechnology Facilities Council, UK; the U.S. Department of Energy, and the U.S. National Sci-ence Foundation.Individuals have received support from the Marie-Curie program and the European ResearchCouncil and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Founda-tion; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; theFonds pour la Formation `a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); eferences the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministryof Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Indus-trial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS program ofFoundation for Polish Science, cofinanced by EU, Regional Development Fund; and the Thalisand Aristeia programs cofinanced by EU-ESF and the Greek NSRF. References [1] ATLAS Collaboration, “Observation of a new particle in the search for the StandardModel Higgs boson with the ATLAS detector at the LHC”,
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Charles University, Prague, Czech Republic
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Helsinki Institute of Physics, Helsinki, Finland
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Lappeenranta University of Technology, Lappeenranta, Finland
T. Tuuva
DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France
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Institut Pluridisciplinaire Hubert Curien, Universit´e de Strasbourg, Universit´e de HauteAlsace Mulhouse, CNRS/IN2P3, Strasbourg, France
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S. Gadrat
Universit´e de Lyon, Universit´e Claude Bernard Lyon 1, CNRS-IN2P3, Institut de PhysiqueNucl´eaire de Lyon, Villeurbanne, France
S. Beauceron, N. Beaupere, G. Boudoul, S. Brochet, C.A. Carrillo Montoya, J. Chasserat,R. Chierici, D. Contardo , P. Depasse, H. El Mamouni, J. Fan, J. Fay, S. Gascon, M. Gouzevitch,B. Ille, T. Kurca, M. Lethuillier, L. Mirabito, S. Perries, J.D. Ruiz Alvarez, L. Sgandurra,V. Sordini, M. Vander Donckt, P. Verdier, S. Viret, H. Xiao Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi,Georgia
Z. Tsamalaidze RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany
C. Autermann, S. Beranek, M. Bontenackels, B. Calpas, M. Edelhoff, L. Feld, O. Hindrichs,K. Klein, A. Ostapchuk, A. Perieanu, F. Raupach, J. Sammet, S. Schael, D. Sprenger, H. Weber,B. Wittmer, V. Zhukov RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany
M. Ata, J. Caudron, E. Dietz-Laursonn, D. Duchardt, M. Erdmann, R. Fischer, A. G ¨uth,T. Hebbeker, C. Heidemann, K. Hoepfner, D. Klingebiel, S. Knutzen, P. Kreuzer,M. Merschmeyer, A. Meyer, M. Olschewski, K. Padeken, P. Papacz, H. Reithler, S.A. Schmitz,L. Sonnenschein, D. Teyssier, S. Th ¨uer, M. Weber
RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany
V. Cherepanov, Y. Erdogan, G. Fl ¨ugge, H. Geenen, M. Geisler, W. Haj Ahmad, F. Hoehle,B. Kargoll, T. Kress, Y. Kuessel, J. Lingemann , A. Nowack, I.M. Nugent, L. Perchalla, O. Pooth,A. Stahl Deutsches Elektronen-Synchrotron, Hamburg, Germany
I. Asin, N. Bartosik, J. Behr, W. Behrenhoff, U. Behrens, A.J. Bell, M. Bergholz , A. Bethani,K. Borras, A. Burgmeier, A. Cakir, L. Calligaris, A. Campbell, S. Choudhury, F. Costanza,C. Diez Pardos, S. Dooling, T. Dorland, G. Eckerlin, D. Eckstein, T. Eichhorn, G. Flucke,A. Geiser, A. Grebenyuk, P. Gunnellini, S. Habib, J. Hauk, G. Hellwig, M. Hempel, D. Horton,H. Jung, M. Kasemann, P. Katsas, J. Kieseler, C. Kleinwort, M. Kr¨amer, D. Kr ¨ucker, W. Lange,J. Leonard, K. Lipka, W. Lohmann , B. Lutz, R. Mankel, I. Marfin, I.-A. Melzer-Pellmann,A.B. Meyer, J. Mnich, A. Mussgiller, S. Naumann-Emme, O. Novgorodova, F. Nowak,E. Ntomari, H. Perrey, A. Petrukhin, D. Pitzl, R. Placakyte, A. Raspereza, P.M. Ribeiro Cipriano,C. Riedl, E. Ron, M. ¨O. Sahin, J. Salfeld-Nebgen, P. Saxena, R. Schmidt , T. Schoerner-Sadenius,M. Schr ¨oder, M. Stein, A.D.R. Vargas Trevino, R. Walsh, C. Wissing A The CMS Collaboration
University of Hamburg, Hamburg, Germany
M. Aldaya Martin, V. Blobel, H. Enderle, J. Erfle, E. Garutti, K. Goebel, M. G ¨orner, M. Gosselink,J. Haller, R.S. H ¨oing, H. Kirschenmann, R. Klanner, R. Kogler, J. Lange, T. Lapsien, T. Lenz,I. Marchesini, J. Ott, T. Peiffer, N. Pietsch, D. Rathjens, C. Sander, H. Schettler, P. Schleper,E. Schlieckau, A. Schmidt, M. Seidel, J. Sibille , V. Sola, H. Stadie, G. Steinbr ¨uck, D. Troendle,E. Usai, L. Vanelderen Institut f ¨ur Experimentelle Kernphysik, Karlsruhe, Germany
C. Barth, C. Baus, J. Berger, C. B ¨oser, E. Butz, T. Chwalek, W. De Boer, A. Descroix, A. Dierlamm,M. Feindt, M. Guthoff , F. Hartmann , T. Hauth , H. Held, K.H. Hoffmann, U. Husemann,I. Katkov , A. Kornmayer , E. Kuznetsova, P. Lobelle Pardo, D. Martschei, M.U. Mozer,Th. M ¨uller, M. Niegel, A. N ¨urnberg, O. Oberst, G. Quast, K. Rabbertz, F. Ratnikov, S. R ¨ocker, F.-P. Schilling, G. Schott, H.J. Simonis, F.M. Stober, R. Ulrich, J. Wagner-Kuhr, S. Wayand, T. Weiler,R. Wolf, M. Zeise Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi,Greece
G. Anagnostou, G. Daskalakis, T. Geralis, S. Kesisoglou, A. Kyriakis, D. Loukas, A. Markou,C. Markou, A. Psallidas, I. Topsis-Giotis
University of Athens, Athens, Greece
L. Gouskos, A. Panagiotou, N. Saoulidou, E. Stiliaris
University of Io´annina, Io´annina, Greece
X. Aslanoglou, I. Evangelou , G. Flouris, C. Foudas , J. Jones, P. Kokkas, N. Manthos,I. Papadopoulos, E. Paradas Wigner Research Centre for Physics, Budapest, Hungary
G. Bencze , C. Hajdu, P. Hidas, D. Horvath , F. Sikler, V. Veszpremi, G. Vesztergombi ,A.J. Zsigmond Institute of Nuclear Research ATOMKI, Debrecen, Hungary
N. Beni, S. Czellar, J. Molnar, J. Palinkas, Z. Szillasi
University of Debrecen, Debrecen, Hungary
J. Karancsi, P. Raics, Z.L. Trocsanyi, B. Ujvari
National Institute of Science Education and Research, Bhubaneswar, India
S.K. Swain
Panjab University, Chandigarh, India
S.B. Beri, V. Bhatnagar, N. Dhingra, R. Gupta, M. Kaur, M. Mittal, N. Nishu, A. Sharma,J.B. Singh
University of Delhi, Delhi, India
Ashok Kumar, Arun Kumar, S. Ahuja, A. Bhardwaj, B.C. Choudhary, A. Kumar, S. Malhotra,M. Naimuddin, K. Ranjan, V. Sharma, R.K. Shivpuri
Saha Institute of Nuclear Physics, Kolkata, India
S. Banerjee, S. Bhattacharya, K. Chatterjee, S. Dutta, B. Gomber, Sa. Jain, Sh. Jain, R. Khurana,A. Modak, S. Mukherjee, D. Roy, S. Sarkar, M. Sharan, A.P. Singh
Bhabha Atomic Research Centre, Mumbai, India
A. Abdulsalam, D. Dutta, S. Kailas, V. Kumar, A.K. Mohanty , L.M. Pant, P. Shukla, A. Topkar1
A. Abdulsalam, D. Dutta, S. Kailas, V. Kumar, A.K. Mohanty , L.M. Pant, P. Shukla, A. Topkar1 Tata Institute of Fundamental Research - EHEP, Mumbai, India
T. Aziz, R.M. Chatterjee, S. Ganguly, S. Ghosh, M. Guchait , A. Gurtu , G. Kole,S. Kumar, M. Maity , G. Majumder, K. Mazumdar, G.B. Mohanty, B. Parida, K. Sudhakar,N. Wickramage Tata Institute of Fundamental Research - HECR, Mumbai, India
S. Banerjee, S. Dugad
Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
H. Arfaei, H. Bakhshiansohi, H. Behnamian, S.M. Etesami , A. Fahim , A. Jafari, M. Khakzad,M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi, B. Safarzadeh , M. Zeinali University College Dublin, Dublin, Ireland
M. Grunewald
INFN Sezione di Bari a , Universit`a di Bari b , Politecnico di Bari c , Bari, Italy M. Abbrescia a , b , L. Barbone a , b , C. Calabria a , b , S.S. Chhibra a , b , A. Colaleo a , D. Creanza a , c , N. DeFilippis a , c , M. De Palma a , b , L. Fiore a , G. Iaselli a , c , G. Maggi a , c , M. Maggi a , B. Marangelli a , b ,S. My a , c , S. Nuzzo a , b , N. Pacifico a , A. Pompili a , b , G. Pugliese a , c , R. Radogna a , b , G. Selvaggi a , b ,L. Silvestris a , G. Singh a , b , R. Venditti a , b , P. Verwilligen a , G. Zito a INFN Sezione di Bologna a , Universit`a di Bologna b , Bologna, Italy G. Abbiendi a , A.C. Benvenuti a , D. Bonacorsi a , b , S. Braibant-Giacomelli a , b , L. Brigliadori a , b ,R. Campanini a , b , P. Capiluppi a , b , A. Castro a , b , F.R. Cavallo 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 , M. Meneghelli a , b , A. Montanari a , F.L. Navarria a , b ,F. Odorici a , A. Perrotta a , F. Primavera a , b , A.M. Rossi a , b , T. Rovelli a , b , G.P. Siroli a , b , N. Tosi a , b ,R. Travaglini a , b INFN Sezione di Catania a , Universit`a di Catania b , CSFNSM c , Catania, Italy S. Albergo a , b , G. Cappello a , M. Chiorboli a , b , S. Costa a , b , F. Giordano a , c ,2 , 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 , V. Ciulli a , b , C. Civinini a , R. D’Alessandro a , b , E. Focardi a , b , E. Gallo a , S. Gonzi a , b ,V. Gori a , b , P. Lenzi a , b , M. Meschini a , S. Paoletti a , G. Sguazzoni a , A. Tropiano a , b INFN Laboratori Nazionali di Frascati, Frascati, Italy
L. Benussi, S. Bianco, F. Fabbri, D. Piccolo
INFN Sezione di Genova a , Universit`a di Genova b , Genova, Italy P. Fabbricatore a , R. Ferretti a , b , F. Ferro a , M. Lo Vetere a , b , R. Musenich a , E. Robutti a , S. Tosi a , b INFN Sezione di Milano-Bicocca a , Universit`a di Milano-Bicocca b , Milano, Italy M.E. Dinardo a , b , S. Fiorendi a , b ,2 , S. Gennai a , R. Gerosa, A. Ghezzi a , b , P. Govoni a , b ,M.T. Lucchini a , b ,2 , S. Malvezzi a , R.A. Manzoni a , b ,2 , A. Martelli a , b ,2 , B. Marzocchi, D. Menasce a ,L. Moroni a , M. Paganoni a , b , D. Pedrini a , 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 , Universit`a dellaBasilicata (Potenza) c , Universit`a G. Marconi (Roma) d , Napoli, Italy S. Buontempo a , N. Cavallo a , c , S. Di Guida a , d , F. Fabozzi a , c , A.O.M. Iorio a , b , L. Lista a ,S. Meola a , d ,2 , M. Merola a , P. Paolucci a ,2 A The CMS Collaboration
INFN Sezione di Padova a , Universit`a di Padova b , Universit`a di Trento (Trento) c , Padova,Italy P. Azzi a , N. Bacchetta a , D. Bisello a , b , A. Branca a , b , R. Carlin a , b , P. Checchia a , T. Dorigo a ,M. Galanti a , b ,2 , F. Gasparini a , b , U. Gasparini a , b , P. Giubilato a , b , A. Gozzelino a , K. Kanishchev a , c ,S. Lacaprara a , I. Lazzizzera a , c , M. Margoni a , b , A.T. Meneguzzo a , b , F. Montecassiano a ,M. Passaseo a , J. Pazzini a , b , N. Pozzobon a , b , P. Ronchese a , b , F. Simonetto a , b , E. Torassa a ,M. Tosi a , b , S. Vanini a , b , P. Zotto a , b , A. Zucchetta a , b , G. Zumerle a , b INFN Sezione di Pavia a , Universit`a di Pavia b , Pavia, Italy M. Gabusi a , b , S.P. Ratti a , b , C. Riccardi a , b , P. Salvini a , P. Vitulo a , b INFN Sezione di Perugia a , Universit`a di Perugia b , Perugia, Italy M. Biasini a , b , G.M. Bilei a , L. Fan `o a , b , P. Lariccia a , b , G. Mantovani a , b , M. Menichelli a , F. Romeo a , b ,A. Saha a , A. Santocchia a , b , A. Spiezia a , b INFN Sezione di Pisa a , Universit`a di Pisa b , Scuola Normale Superiore di Pisa c , Pisa, Italy K. Androsov a ,28 , P. Azzurri a , G. Bagliesi a , J. Bernardini a , T. Boccali a , G. Broccolo a , c , R. Castaldi a ,M.A. Ciocci a ,28 , R. Dell’Orso a , S. Donato a , c , F. Fiori a , c , L. Fo`a a , c , A. Giassi a , M.T. Grippo a ,28 ,A. Kraan a , F. Ligabue a , c , T. Lomtadze a , L. Martini a , b , A. Messineo a , b , C.S. Moon a ,29 , F. Palla a ,2 ,A. Rizzi a , b , A. Savoy-Navarro a ,30 , A.T. Serban a , P. Spagnolo a , P. Squillacioti a ,28 , R. Tenchini a ,G. Tonelli a , b , A. Venturi a , P.G. Verdini a , C. Vernieri a , c INFN Sezione di Roma a , Universit`a di Roma b , Roma, Italy L. Barone a , b , F. Cavallari a , D. Del Re a , b , M. Diemoz a , M. Grassi a , b , C. Jorda a , E. Longo a , b ,F. Margaroli a , b , P. Meridiani a , F. Micheli a , b , S. Nourbakhsh a , b , G. Organtini a , b , R. Paramatti a ,S. Rahatlou a , b , C. Rovelli a , L. Soffi a , b , P. Traczyk a , b INFN Sezione di Torino a , Universit`a di Torino b , Universit`a del Piemonte Orientale (No-vara) c , Torino, Italy N. Amapane a , b , R. Arcidiacono a , c , S. Argiro a , b , M. Arneodo a , c , R. Bellan a , b , C. Biino a ,N. Cartiglia a , S. Casasso a , b , M. Costa a , b , A. Degano a , b , N. Demaria a , C. Mariotti a , S. Maselli a ,E. Migliore a , b , V. Monaco a , b , M. Musich a , M.M. Obertino a , c , G. Ortona a , b , L. Pacher a , b ,N. Pastrone a , M. Pelliccioni a ,2 , A. Potenza a , b , A. Romero a , b , M. Ruspa a , c , R. Sacchi a , b ,A. Solano a , b , A. Staiano a , U. Tamponi a INFN Sezione di Trieste a , Universit`a di Trieste b , Trieste, Italy S. Belforte a , V. Candelise a , b , M. Casarsa a , F. Cossutti a , G. Della Ricca a , b , B. Gobbo a , C. LaLicata a , b , M. Marone a , b , D. Montanino a , b , A. Penzo a , A. Schizzi a , b , T. Umer a , b , A. Zanetti a Kangwon National University, Chunchon, Korea
S. Chang, T.Y. Kim, S.K. Nam
Kyungpook National University, Daegu, Korea
D.H. Kim, G.N. Kim, J.E. Kim, M.S. Kim, D.J. Kong, S. Lee, Y.D. Oh, H. Park, A. Sakharov,D.C. Son
Chonnam National University, Institute for Universe and Elementary Particles, Kwangju,Korea
J.Y. Kim, Zero J. Kim, S. Song
Korea University, Seoul, Korea
S. Choi, D. Gyun, B. Hong, M. Jo, H. Kim, Y. Kim, B. Lee, K.S. Lee, S.K. Park, Y. Roh
University of Seoul, Seoul, Korea
M. Choi, J.H. Kim, C. Park, I.C. Park, S. Park, G. Ryu Sungkyunkwan University, Suwon, Korea
Y. Choi, Y.K. Choi, J. Goh, E. Kwon, J. Lee, H. Seo, I. Yu
Vilnius University, Vilnius, Lithuania
A. Juodagalvis
National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia
J.R. Komaragiri
Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico
H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-de La Cruz , R. Lopez-Fernandez,J. Mart´ınez-Ortega, A. Sanchez-Hernandez, L.M. Villasenor-Cendejas Universidad Iberoamericana, Mexico City, Mexico
S. Carrillo Moreno, F. Vazquez Valencia
Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
H.A. Salazar Ibarguen
Universidad Aut ´onoma de San Luis Potos´ı, San Luis Potos´ı, Mexico
E. Casimiro Linares, A. Morelos Pineda
University of Auckland, Auckland, New Zealand
D. Krofcheck
University of Canterbury, Christchurch, New Zealand
P.H. Butler, R. Doesburg, S. Reucroft
National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan
A. Ahmad, M. Ahmad, M.I. Asghar, J. Butt, Q. Hassan, H.R. Hoorani, W.A. Khan, T. Khurshid,S. Qazi, M.A. Shah, M. Shoaib
National Centre for Nuclear Research, Swierk, Poland
H. Bialkowska, M. Bluj , B. Boimska, T. Frueboes, M. G ´orski, M. Kazana, K. Nawrocki,K. Romanowska-Rybinska, M. Szleper, G. Wrochna, P. Zalewski Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
G. Brona, K. Bunkowski, M. Cwiok, W. Dominik, K. Doroba, A. Kalinowski, M. Konecki,J. Krolikowski, M. Misiura, W. Wolszczak
Laborat ´orio de Instrumenta¸c˜ao e F´ısica Experimental de Part´ıculas, Lisboa, Portugal
P. Bargassa, C. Beir˜ao Da Cruz E Silva, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro,F. Nguyen, J. Rodrigues Antunes, J. Seixas, J. Varela, P. Vischia
Joint Institute for Nuclear Research, Dubna, Russia
I. Golutvin, A. Kamenev, V. Karjavin, V. Konoplyanikov, V. Korenkov, A. Lanev, A. Malakhov,V. Matveev , P. Moisenz, V. Palichik, V. Perelygin, M. Savina, S. Shmatov, S. Shulha,N. Skatchkov, V. Smirnov, E. Tikhonenko, A. Zarubin Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia
V. Golovtsov, Y. Ivanov, V. Kim , P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov,L. Uvarov, S. Vavilov, A. Vorobyev, An. Vorobyev Institute for Nuclear Research, Moscow, Russia
Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov, N. Krasnikov, A. Pashenkov,D. Tlisov, A. Toropin A The CMS Collaboration
Institute for Theoretical and Experimental Physics, Moscow, Russia
V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, G. Safronov, S. Semenov, A. Spiridonov,V. Stolin, E. Vlasov, A. Zhokin
P.N. Lebedev Physical Institute, Moscow, Russia
V. Andreev, M. Azarkin, I. Dremin, M. Kirakosyan, A. Leonidov, G. Mesyats, S.V. Rusakov,A. Vinogradov
Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow,Russia
A. Belyaev, E. Boos, M. Dubinin , L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova,I. Lokhtin, S. Obraztsov, S. Petrushanko, V. Savrin, A. Snigirev State Research Center of Russian Federation, Institute for High Energy Physics, Protvino,Russia
I. Azhgirey, I. Bayshev, S. Bitioukov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine,V. Petrov, R. Ryutin, A. Sobol, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov
University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade,Serbia
P. Adzic , M. Dordevic, M. Ekmedzic, J. Milosevic Centro de Investigaciones Energ´eticas Medioambientales y Tecnol ´ogicas (CIEMAT),Madrid, Spain
M. Aguilar-Benitez, J. Alcaraz Maestre, C. Battilana, E. Calvo, M. Cerrada, M. Chamizo Llatas ,N. Colino, B. De La Cruz, A. Delgado Peris, D. Dom´ınguez V´azquez, C. Fernandez Bedoya,J.P. Fern´andez Ramos, A. Ferrando, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez,S. Goy Lopez, J.M. Hernandez, M.I. Josa, G. Merino, E. Navarro De Martino, A. P´erez-Calero Yzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, M.S. Soares,C. Willmott Universidad Aut ´onoma de Madrid, Madrid, Spain
C. Albajar, J.F. de Troc ´oniz, M. Missiroli
Universidad de Oviedo, Oviedo, Spain
H. Brun, J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, L. LloretIglesias
Instituto de F´ısica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain
J.A. Brochero Cifuentes, I.J. Cabrillo, A. Calderon, J. Duarte Campderros, M. Fernandez,G. Gomez, J. Gonzalez Sanchez, A. Graziano, A. Lopez Virto, J. Marco, R. Marco, C. MartinezRivero, F. Matorras, F.J. Munoz Sanchez, J. Piedra Gomez, T. Rodrigo, A.Y. Rodr´ıguez-Marrero,A. Ruiz-Jimeno, L. Scodellaro, I. Vila, R. Vilar Cortabitarte
CERN, European Organization for Nuclear Research, Geneva, Switzerland
D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis, P. Baillon, A.H. Ball, D. Barney, A. Benaglia,J. Bendavid, L. Benhabib, J.F. Benitez, C. Bernet , G. Bianchi, P. Bloch, A. Bocci, A. Bonato,O. Bondu, C. Botta, H. Breuker, T. Camporesi, G. Cerminara, T. Christiansen, J.A. CoarasaPerez, S. Colafranceschi , M. D’Alfonso, D. d’Enterria, A. Dabrowski, A. David, F. De Guio,A. De Roeck, S. De Visscher, M. Dobson, N. Dupont-Sagorin, A. Elliott-Peisert, J. Eugster,G. Franzoni, W. Funk, M. Giffels, D. Gigi, K. Gill, D. Giordano, M. Girone, M. Giunta, F. Glege,R. Gomez-Reino Garrido, S. Gowdy, R. Guida, J. Hammer, M. Hansen, P. Harris, J. Hegeman,V. Innocente, P. Janot, E. Karavakis, K. Kousouris, K. Krajczar, P. Lecoq, C. Lourenc¸o,N. Magini, L. Malgeri, M. Mannelli, L. Masetti, F. Meijers, S. Mersi, E. Meschi, F. Moortgat, M. Mulders, P. Musella, L. Orsini, E. Palencia Cortezon, L. Pape, E. Perez, L. Perrozzi, A. Petrilli,G. Petrucciani, A. Pfeiffer, M. Pierini, M. Pimi¨a, D. Piparo, M. Plagge, A. Racz, W. Reece,G. Rolandi , M. Rovere, H. Sakulin, F. Santanastasio, C. Sch¨afer, C. Schwick, S. Sekmen,A. Sharma, P. Siegrist, P. Silva, M. Simon, P. Sphicas , D. Spiga, J. Steggemann, B. Stieger,M. Stoye, D. Treille, A. Tsirou, G.I. Veres , J.R. Vlimant, H.K. W ¨ohri, W.D. Zeuner Paul Scherrer Institut, Villigen, Switzerland
W. Bertl, K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, S. K ¨onig,D. Kotlinski, U. Langenegger, D. Renker, T. Rohe
Institute for Particle Physics, ETH Zurich, Zurich, Switzerland
F. Bachmair, L. B¨ani, L. Bianchini, P. Bortignon, M.A. Buchmann, B. Casal, N. Chanon,A. Deisher, G. Dissertori, M. Dittmar, M. Doneg`a, M. D ¨unser, P. Eller, C. Grab, D. Hits,W. Lustermann, B. Mangano, A.C. Marini, P. Martinez Ruiz del Arbol, D. Meister, N. Mohr,C. N¨ageli , P. Nef, F. Nessi-Tedaldi, F. Pandolfi, F. Pauss, M. Peruzzi, M. Quittnat, L. Rebane,F.J. Ronga, M. Rossini, A. Starodumov , M. Takahashi, K. Theofilatos, R. Wallny, H.A. Weber Universit¨at Z ¨urich, Zurich, Switzerland
C. Amsler , M.F. Canelli, V. Chiochia, A. De Cosa, C. Favaro, A. Hinzmann, T. Hreus,M. Ivova Rikova, B. Kilminster, B. Millan Mejias, J. Ngadiuba, P. Robmann, H. Snoek, S. Taroni,M. Verzetti, Y. Yang National Central University, Chung-Li, Taiwan
M. Cardaci, K.H. Chen, C. Ferro, C.M. Kuo, S.W. Li, W. Lin, Y.J. Lu, R. Volpe, S.S. Yu
National Taiwan University (NTU), Taipei, Taiwan
P. Bartalini, P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, P.H. Chen, C. Dietz,U. Grundler, W.-S. Hou, Y. Hsiung, K.Y. Kao, Y.J. Lei, Y.F. Liu, R.-S. Lu, D. Majumder,E. Petrakou, X. Shi, J.G. Shiu, Y.M. Tzeng, M. Wang, R. Wilken
Chulalongkorn University, Bangkok, Thailand
B. Asavapibhop, N. Suwonjandee
Cukurova University, Adana, Turkey
A. Adiguzel, M.N. Bakirci , S. Cerci , C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis,G. Gokbulut, E. Gurpinar, I. Hos, E.E. Kangal, A. Kayis Topaksu, G. Onengut , K. Ozdemir,S. Ozturk , A. Polatoz, K. Sogut , D. Sunar Cerci , B. Tali , H. Topakli , M. Vergili Middle East Technical University, Physics Department, Ankara, Turkey
I.V. Akin, T. Aliev, B. Bilin, S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Guler, G. Karapinar ,K. Ocalan, A. Ozpineci, M. Serin, R. Sever, U.E. Surat, M. Yalvac, M. Zeyrek Bogazici University, Istanbul, Turkey
E. G ¨ulmez, B. Isildak , M. Kaya , O. Kaya , S. Ozkorucuklu Istanbul Technical University, Istanbul, Turkey
H. Bahtiyar , E. Barlas, K. Cankocak, Y.O. G ¨unaydin , F.I. Vardarlı, M. Y ¨ucel National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine
L. Levchuk, P. Sorokin
University of Bristol, Bristol, United Kingdom
J.J. Brooke, E. Clement, D. Cussans, H. Flacher, R. Frazier, J. Goldstein, M. Grimes, G.P. Heath,H.F. Heath, J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold , S. Paramesvaran, A. Poll,S. Senkin, V.J. Smith, T. Williams A The CMS Collaboration
Rutherford Appleton Laboratory, Didcot, United Kingdom
K.W. Bell, A. Belyaev , C. Brew, R.M. Brown, D.J.A. Cockerill, J.A. Coughlan, K. Harder,S. Harper, J. Ilic, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea, I.R. Tomalin,W.J. Womersley, S.D. Worm Imperial College, London, United Kingdom
M. Baber, R. Bainbridge, O. Buchmuller, D. Burton, D. Colling, N. Cripps, M. Cutajar,P. Dauncey, G. Davies, M. Della Negra, W. Ferguson, J. Fulcher, D. Futyan, A. Gilbert,A. Guneratne Bryer, G. Hall, Z. Hatherell, J. Hays, G. Iles, M. Jarvis, G. Karapostoli, M. Kenzie,R. Lane, R. Lucas , L. Lyons, A.-M. Magnan, J. Marrouche, B. Mathias, R. Nandi, J. Nash,A. Nikitenko , J. Pela, M. Pesaresi, K. Petridis, M. Pioppi , D.M. Raymond, S. Rogerson,A. Rose, C. Seez, P. Sharp † , A. Sparrow, A. Tapper, M. Vazquez Acosta, T. Virdee, S. Wakefield,N. Wardle Brunel University, Uxbridge, United Kingdom
J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, D. Leggat, D. Leslie, W. Martin, I.D. Reid,P. Symonds, L. Teodorescu, M. Turner
Baylor University, Waco, USA
J. Dittmann, K. Hatakeyama, A. Kasmi, H. Liu, T. Scarborough
The University of Alabama, Tuscaloosa, USA
O. Charaf, S.I. Cooper, C. Henderson, P. Rumerio
Boston University, Boston, USA
A. Avetisyan, T. Bose, C. Fantasia, A. Heister, P. Lawson, D. Lazic, C. Richardson, J. Rohlf,D. Sperka, J. St. John, L. Sulak
Brown University, Providence, USA
J. Alimena, S. Bhattacharya, G. Christopher, D. Cutts, Z. Demiragli, A. Ferapontov,A. Garabedian, U. Heintz, S. Jabeen, G. Kukartsev, E. Laird, G. Landsberg, M. Luk, M. Narain,M. Segala, T. Sinthuprasith, T. Speer, J. Swanson
University of California, Davis, Davis, USA
R. Breedon, G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway,R. Conway, P.T. Cox, R. Erbacher, M. Gardner, W. Ko, A. Kopecky, R. Lander, T. Miceli,M. Mulhearn, D. Pellett, J. Pilot, F. Ricci-Tam, B. Rutherford, M. Searle, S. Shalhout, J. Smith,M. Squires, M. Tripathi, S. Wilbur, R. Yohay
University of California, Los Angeles, USA
V. Andreev, D. Cline, R. Cousins, S. Erhan, P. Everaerts, C. Farrell, M. Felcini, J. Hauser,M. Ignatenko, C. Jarvis, G. Rakness, P. Schlein † , E. Takasugi, V. Valuev, M. Weber University of California, Riverside, Riverside, USA
J. Babb, R. Clare, J. Ellison, J.W. Gary, G. Hanson, J. Heilman, P. Jandir, F. Lacroix, H. Liu,O.R. Long, A. Luthra, M. Malberti, H. Nguyen, A. Shrinivas, J. Sturdy, S. Sumowidagdo,S. Wimpenny
University of California, San Diego, La Jolla, USA
W. Andrews, J.G. Branson, G.B. Cerati, S. Cittolin, R.T. D’Agnolo, D. Evans, A. Holzner,R. Kelley, D. Kovalskyi, M. Lebourgeois, J. Letts, I. Macneill, S. Padhi, C. Palmer, M. Pieri,M. Sani, V. Sharma, S. Simon, E. Sudano, M. Tadel, Y. Tu, A. Vartak, S. Wasserbaech ,F. W ¨urthwein, A. Yagil, J. Yoo University of California, Santa Barbara, Santa Barbara, USA
D. Barge, J. Bradmiller-Feld, C. Campagnari, T. Danielson, A. Dishaw, K. Flowers, M. FrancoSevilla, P. Geffert, C. George, F. Golf, J. Incandela, C. Justus, R. Maga ˜na Villalba, N. Mccoll,V. Pavlunin, J. Richman, R. Rossin, D. Stuart, W. To, C. West
California Institute of Technology, Pasadena, USA
A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, E. Di Marco, J. Duarte, D. Kcira, A. Mott,H.B. Newman, C. Pena, C. Rogan, M. Spiropulu, V. Timciuc, R. Wilkinson, S. Xie, R.Y. Zhu
Carnegie Mellon University, Pittsburgh, USA
V. Azzolini, A. Calamba, R. Carroll, T. Ferguson, Y. Iiyama, D.W. Jang, M. Paulini, J. Russ,H. Vogel, I. Vorobiev
University of Colorado at Boulder, Boulder, USA
J.P. Cumalat, B.R. Drell, W.T. Ford, A. Gaz, E. Luiggi Lopez, U. Nauenberg, J.G. Smith,K. Stenson, K.A. Ulmer, S.R. Wagner
Cornell University, Ithaca, USA
J. Alexander, A. Chatterjee, J. Chu, N. Eggert, L.K. Gibbons, W. Hopkins, A. Khukhunaishvili,B. Kreis, N. Mirman, G. Nicolas Kaufman, J.R. Patterson, A. Ryd, E. Salvati, W. Sun, W.D. Teo,J. Thom, J. Thompson, J. Tucker, Y. Weng, L. Winstrom, P. Wittich
Fairfield University, Fairfield, USA
D. Winn
Fermi National Accelerator Laboratory, Batavia, USA
S. Abdullin, M. Albrow, J. Anderson, G. Apollinari, L.A.T. Bauerdick, A. Beretvas, J. Berryhill,P.C. Bhat, K. Burkett, J.N. Butler, V. Chetluru, H.W.K. Cheung, F. Chlebana, S. Cihangir,V.D. Elvira, I. Fisk, J. Freeman, Y. Gao, E. Gottschalk, L. Gray, D. Green, S. Gr ¨unendahl,O. Gutsche, D. Hare, R.M. Harris, J. Hirschauer, B. Hooberman, S. Jindariani, M. Johnson,U. Joshi, K. Kaadze, B. Klima, S. Kwan, J. Linacre, D. Lincoln, R. Lipton, T. Liu, J. Lykken,K. Maeshima, J.M. Marraffino, V.I. Martinez Outschoorn, S. Maruyama, D. Mason, P. McBride,K. Mishra, S. Mrenna, Y. Musienko , S. Nahn, C. Newman-Holmes, V. O’Dell, O. Prokofyev,N. Ratnikova, E. Sexton-Kennedy, S. Sharma, A. Soha, W.J. Spalding, L. Spiegel, L. Taylor,S. Tkaczyk, N.V. Tran, L. Uplegger, E.W. Vaandering, R. Vidal, A. Whitbeck, J. Whitmore,W. Wu, F. Yang, J.C. Yun University of Florida, Gainesville, USA
D. Acosta, P. Avery, D. Bourilkov, T. Cheng, S. Das, M. De Gruttola, G.P. Di Giovanni,D. Dobur, R.D. Field, M. Fisher, Y. Fu, I.K. Furic, J. Hugon, B. Kim, J. Konigsberg, A. Korytov,A. Kropivnitskaya, T. Kypreos, J.F. Low, K. Matchev, P. Milenovic , G. Mitselmakher, L. Muniz,A. Rinkevicius, L. Shchutska, N. Skhirtladze, M. Snowball, J. Yelton, M. Zakaria Florida International University, Miami, USA
V. Gaultney, S. Hewamanage, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez
Florida State University, Tallahassee, USA
T. Adams, A. Askew, J. Bochenek, J. Chen, B. Diamond, J. Haas, S. Hagopian, V. Hagopian,K.F. Johnson, H. Prosper, V. Veeraraghavan, M. Weinberg
Florida Institute of Technology, Melbourne, USA
M.M. Baarmand, B. Dorney, M. Hohlmann, H. Kalakhety, F. Yumiceva
University of Illinois at Chicago (UIC), Chicago, USA
M.R. Adams, L. Apanasevich, V.E. Bazterra, R.R. Betts, I. Bucinskaite, R. Cavanaugh, A The CMS Collaboration
O. Evdokimov, L. Gauthier, C.E. Gerber, D.J. Hofman, S. Khalatyan, P. Kurt, D.H. Moon,C. O’Brien, C. Silkworth, P. Turner, N. Varelas
The University of Iowa, Iowa City, USA
U. Akgun, E.A. Albayrak , B. Bilki , W. Clarida, K. Dilsiz, F. Duru, M. Haytmyradov, J.-P. Merlo, H. Mermerkaya , A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul, Y. Onel,F. Ozok , R. Rahmat, S. Sen, P. Tan, E. Tiras, J. Wetzel, T. Yetkin , K. Yi Johns Hopkins University, Baltimore, USA
B.A. Barnett, B. Blumenfeld, S. Bolognesi, D. Fehling, A.V. Gritsan, P. Maksimovic, C. Martin,M. Swartz
The University of Kansas, Lawrence, USA
P. Baringer, A. Bean, G. Benelli, J. Gray, R.P. Kenny III, M. Murray, D. Noonan, S. Sanders,J. Sekaric, R. Stringer, Q. Wang, J.S. Wood
Kansas State University, Manhattan, USA
A.F. Barfuss, I. Chakaberia, A. Ivanov, S. Khalil, M. Makouski, Y. Maravin, L.K. Saini,S. Shrestha, I. Svintradze
Lawrence Livermore National Laboratory, Livermore, USA
J. Gronberg, D. Lange, F. Rebassoo, D. Wright
University of Maryland, College Park, USA
A. Baden, B. Calvert, S.C. Eno, J.A. Gomez, N.J. Hadley, R.G. Kellogg, T. Kolberg, Y. Lu,M. Marionneau, A.C. Mignerey, K. Pedro, A. Skuja, J. Temple, M.B. Tonjes, S.C. Tonwar
Massachusetts Institute of Technology, Cambridge, USA
A. Apyan, R. Barbieri, G. Bauer, W. Busza, I.A. Cali, M. Chan, L. Di Matteo, V. Dutta, G. GomezCeballos, M. Goncharov, D. Gulhan, M. Klute, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, T. Ma,C. Paus, D. Ralph, C. Roland, G. Roland, G.S.F. Stephans, F. St ¨ockli, K. Sumorok, D. Velicanu,J. Veverka, B. Wyslouch, M. Yang, A.S. Yoon, M. Zanetti, V. Zhukova
University of Minnesota, Minneapolis, USA
B. Dahmes, A. De Benedetti, A. Gude, S.C. Kao, K. Klapoetke, Y. Kubota, J. Mans, N. Pastika,R. Rusack, A. Singovsky, N. Tambe, J. Turkewitz
University of Mississippi, Oxford, USA
J.G. Acosta, L.M. Cremaldi, R. Kroeger, S. Oliveros, L. Perera, D.A. Sanders, D. Summers
University of Nebraska-Lincoln, Lincoln, USA
E. Avdeeva, K. Bloom, S. Bose, D.R. Claes, A. Dominguez, R. Gonzalez Suarez, J. Keller,D. Knowlton, I. Kravchenko, J. Lazo-Flores, S. Malik, F. Meier, G.R. Snow
State University of New York at Buffalo, Buffalo, USA
J. Dolen, A. Godshalk, I. Iashvili, S. Jain, A. Kharchilava, A. Kumar, S. Rappoccio
Northeastern University, Boston, USA
G. Alverson, E. Barberis, D. Baumgartel, M. Chasco, J. Haley, A. Massironi, D. Nash, T. Orimoto,D. Trocino, D. Wood, J. Zhang
Northwestern University, Evanston, USA
A. Anastassov, K.A. Hahn, A. Kubik, L. Lusito, N. Mucia, N. Odell, B. Pollack, A. Pozdnyakov,M. Schmitt, S. Stoynev, K. Sung, M. Velasco, S. Won University of Notre Dame, Notre Dame, USA
D. Berry, A. Brinkerhoff, K.M. Chan, A. Drozdetskiy, M. Hildreth, C. Jessop, D.J. Karmgard,N. Kellams, J. Kolb, K. Lannon, W. Luo, S. Lynch, N. Marinelli, D.M. Morse, T. Pearson,M. Planer, R. Ruchti, J. Slaunwhite, N. Valls, M. Wayne, M. Wolf, A. Woodard
The Ohio State University, Columbus, USA
L. Antonelli, B. Bylsma, L.S. Durkin, S. Flowers, C. Hill, R. Hughes, K. Kotov, T.Y. Ling,D. Puigh, M. Rodenburg, G. Smith, C. Vuosalo, B.L. Winer, H. Wolfe, H.W. Wulsin
Princeton University, Princeton, USA
E. Berry, P. Elmer, V. Halyo, P. Hebda, A. Hunt, P. Jindal, S.A. Koay, P. Lujan, D. Marlow,T. Medvedeva, M. Mooney, J. Olsen, P. Pirou´e, X. Quan, A. Raval, H. Saka, D. Stickland, C. Tully,J.S. Werner, S.C. Zenz, A. Zuranski
University of Puerto Rico, Mayaguez, USA
E. Brownson, A. Lopez, H. Mendez, J.E. Ramirez Vargas
Purdue University, West Lafayette, USA
E. Alagoz, D. Benedetti, G. Bolla, D. Bortoletto, M. De Mattia, A. Everett, Z. Hu, M.K. Jha,M. Jones, K. Jung, M. Kress, N. Leonardo, D. Lopes Pegna, V. Maroussov, P. Merkel, D.H. Miller,N. Neumeister, B.C. Radburn-Smith, I. Shipsey, D. Silvers, A. Svyatkovskiy, F. Wang, W. Xie,L. Xu, H.D. Yoo, J. Zablocki, Y. Zheng
Purdue University Calumet, Hammond, USA
N. Parashar
Rice University, Houston, USA
A. Adair, B. Akgun, K.M. Ecklund, F.J.M. Geurts, W. Li, B. Michlin, B.P. Padley, R. Redjimi,J. Roberts, J. Zabel
University of Rochester, Rochester, USA
B. Betchart, A. Bodek, R. Covarelli, P. de Barbaro, R. Demina, Y. Eshaq, T. Ferbel, A. Garcia-Bellido, P. Goldenzweig, J. Han, A. Harel, D.C. Miner, G. Petrillo, D. Vishnevskiy, M. Zielinski
The Rockefeller University, New York, USA
A. Bhatti, R. Ciesielski, L. Demortier, K. Goulianos, G. Lungu, S. Malik, C. Mesropian
Rutgers, The State University of New Jersey, Piscataway, USA
S. Arora, A. Barker, J.P. Chou, C. Contreras-Campana, E. Contreras-Campana, D. Duggan,J. Evans, D. Ferencek, Y. Gershtein, R. Gray, E. Halkiadakis, D. Hidas, A. Lath, S. Panwalkar,M. Park, R. Patel, V. Rekovic, J. Robles, S. Salur, S. Schnetzer, C. Seitz, S. Somalwar, R. Stone,S. Thomas, P. Thomassen, M. Walker
University of Tennessee, Knoxville, USA
K. Rose, S. Spanier, Z.C. Yang, A. York
Texas A&M University, College Station, USA
O. Bouhali , R. Eusebi, W. Flanagan, J. Gilmore, T. Kamon , V. Khotilovich, V. Krutelyov,R. Montalvo, I. Osipenkov, Y. Pakhotin, A. Perloff, J. Roe, A. Safonov, T. Sakuma, I. Suarez,A. Tatarinov, D. Toback Texas Tech University, Lubbock, USA
N. Akchurin, C. Cowden, J. Damgov, C. Dragoiu, P.R. Dudero, J. Faulkner, K. Kovitanggoon,S. Kunori, S.W. Lee, T. Libeiro, I. Volobouev A The CMS Collaboration
Vanderbilt University, Nashville, USA
E. Appelt, A.G. Delannoy, S. Greene, A. Gurrola, W. Johns, C. Maguire, Y. Mao, A. Melo,M. Sharma, P. Sheldon, B. Snook, S. Tuo, J. Velkovska
University of Virginia, Charlottesville, USA
M.W. Arenton, S. Boutle, B. Cox, B. Francis, J. Goodell, R. Hirosky, A. Ledovskoy, H. Li, C. Lin,C. Neu, J. Wood
Wayne State University, Detroit, USA
S. Gollapinni, R. Harr, P.E. Karchin, C. Kottachchi Kankanamge Don, P. Lamichhane
University of Wisconsin, Madison, USA
D.A. Belknap, L. Borrello, D. Carlsmith, M. Cepeda, S. Dasu, S. Duric, E. Friis, M. Grothe,R. Hall-Wilton, M. Herndon, A. Herv´e, P. Klabbers, J. Klukas, A. Lanaro, C. Lazaridis,A. Levine, R. Loveless, A. Mohapatra, I. Ojalvo, T. Perry, G.A. Pierro, G. Polese, I. Ross,T. Sarangi, A. Savin, W.H. Smith, N. Woods † : Deceased1: Also at Vienna University of Technology, Vienna, Austria2: Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland3: Also at Institut Pluridisciplinaire Hubert Curien, Universit´e de Strasbourg, Universit´e deHaute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France4: Also at National Institute of Chemical Physics and Biophysics, Tallinn, Estonia5: Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University,Moscow, Russia6: Also at Universidade Estadual de Campinas, Campinas, Brazil7: Also at California Institute of Technology, Pasadena, USA8: Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France9: Also at Suez University, Suez, Egypt10: Also at British University in Egypt, Cairo, Egypt11: Also at Cairo University, Cairo, Egypt12: Also at Fayoum University, El-Fayoum, Egypt13: Also at Helwan University, Cairo, Egypt14: Now at Ain Shams University, Cairo, Egypt15: Also at Universit´e de Haute Alsace, Mulhouse, France16: Also at Joint Institute for Nuclear Research, Dubna, Russia17: Also at Brandenburg University of Technology, Cottbus, Germany18: Also at The University of Kansas, Lawrence, USA19: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary20: Also at E ¨otv ¨os Lor´and University, Budapest, Hungary21: Also at Tata Institute of Fundamental Research - HECR, Mumbai, India22: Now at King Abdulaziz University, Jeddah, Saudi Arabia23: 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 Sharif University of Technology, Tehran, 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 Centre National de la Recherche Scientifique (CNRS) - IN2P3, Paris, France30: Also at Purdue University, West Lafayette, USA1