Measurements of t(t)over-bar charge asymmetry using dilepton final states in pp collisions at root s=8 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Measurements

of

tt charge

asymmetry

using

dilepton

final

states

in

pp

collisions

at

√

s

=

8

TeV

Receivedinrevisedform12June2016 Accepted4July2016

Availableonline9July2016 Editor:M.Doser Keywords: CMS Physics Top Chargeasymmetry

Thechargeasymmetryintt eventsismeasuredusingdileptonfinalstatesproducedinpp collisionsat theLHCat√s₌8TeV.Thedata sample,collectedwiththeCMSdetector,correspondstoanintegrated luminosity of 19.5fb−1.The measurements are performedusing events with two oppositelycharged leptons (electrons ormuons) and two ormore jets, where atleast one of the jets is identified as originating from a bottom quark. The charge asymmetry is measured from differencesin kinematic distributions,unfoldedtothepartonlevel,ofpositivelyandnegativelychargedtopquarksandleptons. Thett andleptonicinclusivechargeasymmetriesarefoundtobe0.011±0.011(stat)±0.007(syst) and 0.003±0.006(stat)±0.003(syst),respectively.Theseresults,aswellaschargeasymmetrymeasurements madeasafunctionoftheinvariantmass,rapidity,andtransverse momentumofthett system,are in agreementwithpredictionsofthestandardmodel.

©2016TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Theexceptionallylargemassofthetopquark,measuredbythis experimentasmt=172.44±0.48GeV[1],suggeststhetop quark

could havean important connection to physics beyondthe stan-dard model (SM), particularly in the mechanism of electroweak (EW) symmetry breaking. Precision measurements of top quark properties have the potential to identify the first hints of new particles,particularlythosewithstrongercouplingsto topquarks than to other fundamental particles. The SM predicts a charge asymmetry in tt production at hadron colliders through quark– antiquarkannihilation.This asymmetry iscaused by the interfer-encebetweentheBornandtheboxdiagrams,aswellasbetween theinitial- andfinal-stateradiationdiagrams,andispredictedby quantum chromodynamics (QCD) calculations at next-to-leading order(NLO) [2,3].Early measurements ofthis asymmetry by the CDF[4] andD0 [5]Collaborations exceeded the NLO predictions [2,3] by abouttwo standard deviations,andthe discrepancy was morepronounced inthe CDFevents withlarge tt invariantmass (M_tt>450GeV). Theseresultshaveledtoconsiderations thatthe anomalousasymmetrymightbegeneratedbytree-levelexchanges of new particles or by interference effects from new physics at highermassscales,notdirectly observableattheLHC[6].Recent

 _{E-mailaddress:cms-publication-committee-chair@cern.ch.}

developmentsinexperimentaltechniques[7,8]andtheoretical pre-dictions such as the inclusion of EW [9–12] and next-to-next-to-leading-order (NNLO) QCD [13,14] correctionshave largely re-solved the disagreement between theory and the Tevatron mea-surements.Nonetheless,thechargeasymmetry remainsan impor-tantprobeofnewphysics.

At theTevatron,collidingvalencequarks fromthe protonand antiproton beams result in asymmetric rapidity ( y) distributions oftopquarksandantiquarks.The proton–proton(pp) initialstate attheLHCisexpectedtoproducetopquark andantiquark rapid-ity distributions that are symmetric about y=0.However, since thequarks intheinitialstate can befromvalence, whilethe an-tiquarks arefromthe sea,the largeraverage momentum-fraction of quarks leads to an excess of top quarks produced in the for-warddirections.TherapiditydistributionoftopquarksintheSM isthereforebroaderthanthatofthemorecentrallyproducedtop antiquarks,meaning |yt| = |yt| − |yt|isa suitableobservable to

measurethett chargeasymmetry,definedintermsofeventyields N as

AC=

N(|yt| >0)−N(|yt| <0)

N(|yt| >0)+N(|yt| <0)

.

Whilethe measurementof AC reliesonthereconstruction ofthe

top quark andantiquark directions, an advantageof the dilepton finalstateisthatonecanalternativelymeasuretheleptoniccharge

http://dx.doi.org/10.1016/j.physletb.2016.07.006

0370-2693/©2016TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

asymmetrydefinedusingonlytheleptonpseudorapidities[15]η± as

Alep_C =N(|η| >0)−N(|η| <0) N(|η| >0)+N(|η| <0) ,

where|η| = |η+| − |η−|.Thisobservableisusefulbecauseitis free oftheambiguitiesassociatedwiththe topquark reconstruc-tion, andbecause the correlation betweenthe directionof a top quarkanditsdecayproductstransmitsanasymmetryintheparent top quarks to the daughterleptons. Furthermore, its dependence onthetopquarkpolarizationimpliesthatitisnotfullycorrelated with AC andprovides complementary information [16].Previous ATLASandCMSmeasurementsofAC usingdatafrompp collisions

at √s=7TeV [17,18] and 8TeV [19–22], and of Alep_C using the 7TeV datasamples[23,24],areconsistentwiththeSMpredictions. InthisLetter,measurementsarepresentedofAC andAlepC from

tt eventsinthedileptonfinal states,usingCMSdatafrompp col-lisions at √s=8TeV corresponding to an integrated luminosity of19.5fb−1.The analysisstrategy is similar to that presentedin Ref. [23] with manyimprovements, most importantlyin the un-foldingtechnique.Thisallowsforfulldifferentialmeasurementsof AC and Alep_C ,whicharemadeasa functionof Mtt aswell asthe

absoluterapidity andthetransverse momentumof thett system inthelaboratoryframe(|y_tt|andptt_T).Furthermore,thelargerdata sampleusedhereaswellasimprovementsmadeintheresolution ofthetopquarkreconstructionleadtobetterstatisticalprecision. 2. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ing solenoidof 6 m internal diameter, providinga magnetic field of3.8 T. Withinthe solenoidvolume are a siliconpixel andstrip tracker, a lead tungstate crystal electromagnetic calorimeter, and a brass and scintillator hadron calorimeter, each composed of a barrelandtwo endcapsections.Forward calorimetersextendthe pseudorapiditycoverageprovidedbythebarrelandendcap detec-tors. Gas-ionization detectors embedded in the steel flux-return yoke outside the solenoid provide additional measurements of muons.AmoredetaileddescriptionoftheCMSdetector,together witha definitionofthe coordinatesystemused andtherelevant kinematicvariables,canbefoundinRef.[15].

3. Eventselectionandreconstruction

Theeventselectionforthisanalysisisidenticaltothatusedin Ref.[25]andisonlybrieflydescribedinthissection.The particle-flow (PF)method [26,27] is used to reconstructfinal-state parti-cles.Events arerequiredtohaveexactlytwoisolated [25]leptons (electrons [28] or muons [29]) of opposite electric charge, with pT>20GeV and |η| <2.4.The dilepton pairinvariant mass M isrequiredtobeabove20GeV.Forsame-flavorleptons,M must also not be within 15GeV of the Z boson mass to suppressthe Drell–Yan(Z/γ_{+jets)background.}

Theanti-kTclusteringalgorithm[30]withadistanceparameter

of0.5 isused to formjetsfrom thePF objects. The contribution to thejet energyfromadditional interactions inthe samebunch crossing (pileup) is estimated for each event using the jet area method [31], and is subtracted from the overall jet pT. At least

twojetswithpT>30GeV and|η| <2.4 arerequiredineachevent.

Atleastone ofthesejetsmustbe consistentwithcontaining the decay of a heavy-flavor hadron, as identified using the medium operatingpointofthecombinedsecondaryvertex(CSV)b tagging algorithm[32].Werefertosuchjetsasb-taggedjets.

The missingtransverse momentum vector p_Tmiss isdefined as the negative vector sumof the pT of all PF objectsover the full

calorimetercoverage(|η| <5).ItsmagnitudeisreferredtoasEmiss_T . The calibrations that are applied to theenergy measurements of jets are propagated to a correction of p_Tmiss. The Emiss_T value is required to exceed 40GeV inevents with same-flavor leptons in order to further suppressthe Drell–Yan background. There is no Emiss_T requirementfore±μ∓ events.

The inclusivemeasurementof AC andall differential

measure-mentspresentedhererequirereconstructionofthett system.Each signal eventhastwo neutrinos,andthereisalsoatwofold ambi-guityincombiningtheb jetswiththeleptons.In62%oftheevents passingtheeventselectionrequirements,onlyoneoftheselected jetsisb tagged.Inthoseeventstheuntaggedjetwiththehighest ranking by theCSV algorithmis assumedtobe thesecond b jet. Solutionsfortheneutrinomomentaarefoundanalytically assum-ingmt=172.5GeV.Eacheventcanhaveupto8possiblesolutions,

and the one with the maximum weight obtained usingthe ma-trixweighting technique[33] ischosenasthemostprobable.For eventswithnophysicalsolution,weattempttofindasolutionfor thesumofneutrinopT ascloseaspossibletothemeasured pTmiss

[34,35]. Nonetheless, no solution is found for approximately16% of the events,both indata andsimulation. Events withno solu-tionsareusedonlyintheinclusivemeasurementofAlep_C ,although theresultsdonotsignificantlychangeifthoseeventsareexcluded. The signsof|yt|and|η|arecorrectlyreconstructedin74.9% and99.5% ofselectedsimulatedtt events,respectively.

4. Eventsamplesandbackgroundestimation

The simulated tt events used in this analysis are generated using the mc@nlo 3.41 [36,37] Monte Carlo (MC) event gener-ator, with mt=172.5GeV and the CTEQ6M parton distribution

functions(PDFs)[38].Thesubsequentpartonshoweringand frag-mentation are done using herwig 6.520 [39]. Simulations with different values of mt and the renormalization and factorization

scales (μR and μF)areusedtoevaluatetheassociatedsystematic

uncertainties. Events withdileptonic tt decays, includingtau lep-tonsthat decayleptonically, aredefinedassignal,while allother tt decaymodesaretreatedasbackground.Backgroundeventsfrom theW+jets,Drell–Yan, diboson(WW,WZ,andZZ),triboson,and tt+boson processesaregeneratedwith MadGraph 5.1.3.30[40,41], while single top quark events are generated using powheg 1.0 [42–46].The parton showeringand fragmentationare performed using pythia 6.4.22 [47],which is also usedfor an alternative tt event sample generated using powheg. Cross sections calculated to NLO or NNLO are used to normalize the background samples [48–56].

For all MC generated events, pileup is simulated with pythia and superimposed on the hard collisions using a pileup mul-tiplicity distribution that reflects the luminosity profile of the analyzed data. The CMS detector response is simulated using a Geant_{4-based model [57], andthe events are reconstructed and} analyzed with the same software used to process the data. The measured trigger efficiencies are used to weight the simulated events to account for the trigger requirement, while the lepton selection efficiencies (reconstruction,identification, and isolation) are consistent between data and simulation [25,58]. The differ-ences between b tagging efficiencies measured indata and sim-ulation[32]areaccountedforusingcorrectionfactors.

Thetotalcontributionfrombackgroundeventstothedata sam-ple is expectedto be 9%, ofwhich abouthalfcomes fromsingle top quark production in association with a W boson (tW), with dileptonic decays. Severalcontrol regions (CRs) in data are used to validatethe backgroundestimatesfromsimulationfortW and Z/γ∗+jets production andfor eventswithincorrectly identified leptons. TheCRsareselectedtohavesimilar kinematicproperties

tothe signal region, butwithone or two requirementsinverted, thus enriching them in different background contributions [25]. AgreementbetweendataandsimulationisobservedinthetW CR, andwe assign a 25% uncertainty in the tW cross section based ontherecent CMSmeasurementof23.4±5.4pb[59].The other CRsareusedtoderivescalefactors(SFs)tomultiplythesimulated eventyields forthecorresponding backgroundprocess, with sys-tematicuncertaintiesestimatedfromthe envelopeofvariationin theSFvalueusingthethreedileptonflavorcombinationsand var-iousalternativeCRs.

Other processes,including tt productionin association witha bosonaswell asdibosonandtribosonproduction,contributeless than20%ofthetotalbackgroundandareestimatedfrom simula-tionalone.RecentCMSmeasurements[60–62]indicateagreement betweenthepredictedandmeasuredcrosssectionsforthese pro-cesses,andtheir smallyields permitthe choiceofa conservative systematicuncertaintyof50%withnegligibleeffectontheanalysis precision.

A comparison of the observed and predicted distributions of

|yt|and|η|canbefoundinthesupplementarymaterial. 5. Unfoldingthedistributions

The measured distributions are distorted, relative to the true underlyingdistributions,bytheacceptanceofthedetector,the ef-ficiencyofthetriggerandeventselection,andthefiniteresolution ofthereconstructedkinematicquantities.Aftersubtractionofthe predictedbackground, we correctthe measured distributions for theseeffectsusinganunfoldingprocedurethatestimatesthe cor-respondingparton-level distributions.Inthecontextoftheoretical calculationsandpartonshowereventgenerators,the parton-level topquark isdefinedbeforeitdecaysanditskinematicproperties includetheeffects ofrecoil frominitial- and final-stateradiation intherestoftheeventandfromfinal-stateradiationfromthetop quark itself. The parton-level charged lepton, produced from the decayof theintermediate W boson, is definedbefore the lepton decaysorradiatesanyphotons.

Weusesixbinsofvaryingwidthinthe|yt|parton-level

dis-tribution that are well matched to the reconstruction resolution and contain approximately equal numbers of events. The |η| distributiondepends onlyon lepton measurements, and the bet-ter resolution allows us to use 12 bins. For the reconstruction-leveldistributions, we use twice asmany bins asthose usedfor the parton-level distributions. The unfolding is performed using the TUnfold package[63],usingregularizationbased onthe cur-vature of the simulatedsignal distribution to suppressstatistical fluctuationsinthehighfrequencycomponentsoftheunfolded dis-tribution.The regularization strength isoptimized by minimizing theaverageglobalcorrelationcoefficientintheunfolded distribu-tion; the resulting regularization is relatively weak, contributing atthelevelof5% tothetotal χ2 _{minimizedbythealgorithm.An}

analogousunfoldingprocedureisusedtomeasure AC andAlepC

dif-ferentially,afterintroducinga furtherthreebinsineach ofthett systemkinematicvariablesM_tt,|y_tt|,andptt

T.

6. Systematicuncertainties

Mostof the systematicuncertainties concern detector perfor-manceandthemodeling ofthe signal andbackgroundprocesses and are estimated from the change in the measurement when varying thesimulated eventsamples usedfor theunfolding. The uncertaintyfromthe jet energyscale correctionsisestimated by varyingthejet energies withintheir uncertainties [64] and prop-agating this to the pmiss

T . Similarly, the jet energy resolution is

Table 1

Systematicuncertaintiesintheinclusivevaluesofthechargeasymmetriesobtained fromtheunfoldeddistributions.Uncertaintiesoflessthan0.0005aremarkedbya dash(—).

Charge asymmetry variable AC AlepC

Experimental systematic uncertainties

Jet energy scale 0.001 — Jet energy resolution 0.002 — Lepton energy scale 0.001 —

Background 0.001 0.001

Pileup — —

b tagging efficiency 0.001 —

Lepton selection — —

tt modeling uncertainties

Parton distribution functions 0.001 0.001

Top quark pT 0.001 —

Renormalization and factorization scales 0.003 0.002 Top quark mass 0.001 0.001

Hadronization 0.003 —

Unfolding (simulation statistical) 0.005 0.002 Unfolding (regularization) — — Total systematic uncertainty 0.007 0.003

varied by2–5%,dependingon the η ofthejet[64],andthe elec-tron energyscale isvaried by ±0.6% (±1.5%) forbarrel(endcap) electrons, asestimatedfromcomparisonsbetweenmeasured and simulated Z boson events [28]. The uncertainty in muon ener-gies is negligible. The uncertainty in the background subtraction isobtainedbyvaryingthenormalizationofeachbackground com-ponentbytheuncertaintiesdescribedinSection4.

Manyof thesignal modelingand simulationuncertainties are evaluated by using weights to vary the mc@nlo tt sample: the simulatedpileupmultiplicitydistributionischangedwithinits un-certainty; the correction factorsbetween dataandsimulation for the b tagging efficiency[32],trigger efficiency, andlepton selec-tionefficiencyareshiftedupanddownbytheiruncertainties;and thePDFsarevariedusingthePDF4LHCprocedure[65,66].Previous CMSstudies[67,68]haveshownthatthepTdistributionofthetop

quark in data issofter than inthe NLO simulation of tt produc-tion. Since the origin ofthe discrepancy is not fully understood, thechangeinthemeasurementwhenreweighting the mc@nlo tt sample to matchthe top quark pT spectrum in data istaken as

a systematicuncertainty associatedwithsignalmodeling. Further signalmodelinguncertaintiesareevaluatedusingthededicatedtt samples: μR and μF are simultaneously varied up anddown by

a factor of 2, mt is varied by ±1GeV, andthe tt sample

gener-atedwith powheg and pythia isusedtomeasuretheuncertainty in hadronizationmodeling fromthe difference betweenthe her-wigand pythia descriptions.Thesystematicuncertaintyestimates evaluated usingdedicated tt sampleshave asignificant statistical uncertainty governed by the number of events in the simulated samples.Toavoidunderestimationoftheseuncertainties,the max-imum ofthe estimated systematicuncertainty andthe statistical uncertaintyinthatestimateistakenasthefinalsystematic uncer-tainty.

Theuncertaintyintheunfoldingprocedureisdominatedbythe statisticaluncertaintyarisingfromthelimitednumberofeventsin the mc@nlo tt sample.The uncertaintyfromtheregularization is found tobe small incomparison. The systematicuncertainties in theinclusivechargeasymmetryvaluesobtainedfromtheunfolded distributions aresummarizedinTable 1.Theindividualtermsare addedinquadraturetoestimatethetotalsystematicuncertainties. Forboth AC and Alep_C ,thedominantsystematicuncertaintyarises

fromthelimitednumberofsimulatedeventsusedforthe unfold-ing.

Fig. 1. Background-subtractedandunfoldeddistributionsof|yt|(top)and|η|

(bottom)fromdata(points),normalizedtounitarea.Parton-levelpredictionsfrom the mc@nlo simulationandcalculations atNLO(QCD+EW)[12]areshownby dashedandsolidhistograms,respectively.Theratioofthemeasuredbinvaluesto the mc@nlo predictionisshowninthebottompanel.Theverticalbarsshowthe totaluncertainty,thestatisticalcomponentofwhichismarkedbyahorizontal tick. Thefirstandlastbinsofeachplotincludeunderflowandoverflowevents, respec-tively.

7. Results

Theunfoldednormalizeddifferentialcrosssectionfromthe se-lected events indata is shownasa function of |yt| and|η| in Fig. 1, along with the parton-level predictions for tt produc-tionobtainedfromcalculationsatNLOintheSMgaugecouplings (QCD+EW) [12] and with the mc@nlo generator (which does not includeEW corrections).The corresponding AC and AlepC

val-ues are presented in Table 2. Correlations between the contents of different bins, introduced by the unfolding process and from the systematicuncertainties, are accountedfor inthe calculation oftheuncertainties.The measuredvaluesareconsistent withthe expectationsfromtheSM.Thechargeasymmetriesasafunctionof Mtt,|ytt|,andpttT arealsomeasured.Theresults,whichareshown

inFig. 2,are consistent withthe mc@nlo simulationpredictions, aswell aswiththeNLO(QCD+EW)calculationsforthe M_tt and

Table 2

Theinclusivechargeasymmetrymeasurementsobtainedfromtheunfolded distri-butionsandtheparton-levelpredictionsfromthe mc@nlo simulationand calcula-tionsatNLO(QCD+EW)[12].Forthedata,thefirstuncertaintyisstatisticaland thesecondissystematic.Theuncertaintiesinthe mc@nlo resultsarestatisticaland theuncertaintiesintheNLOcalculationscomefromvaryingtogetherμR andμF

upanddownbyafactoroftwo.

Variable Data mc@nlo NLO (QCD+EW)

AC 0.011±0.011±0.007 0.006±0.001 0.0111±0.0004

AlepC 0.003±0.006±0.003 0.004±0.001 0.0064±0.0003

|ytt|dependencies.No comparisonismadewithNLOcalculations

for the ptt_T dependencies as it is expected that the effect of the parton shower process on the ptt_T distribution makes fixed-order calculationsaninadequateapproximationofthedata.

8. Summary

Measurements are presented of the charge asymmetry in tt dilepton final states from distributions, unfolded to the parton level, of the absolute rapidity (pseudorapidity) difference of top quarks(leptons)withpositiveandnegativecharge. Thedata sam-ple corresponds to an integrated luminosity of 19.5fb−1 from pp collisions at √s=8TeV, collected by the CMS experimentat the LHC. The tt and leptonic inclusive charge asymmetries are found to be, respectively, 0.011±0.011(stat)±0.007(syst) and 0.003±0.006(stat)±0.003(syst) whenmeasured inclusively.The chargeasymmetriesarealsomeasuredasafunctionofthe invari-ant mass, absolute rapidity, andtransverse momentum of the tt system in the laboratory frame. Althoughstatistically limited, all measurements areinagreement withthe standardmodel predic-tions. Future measurements at√s=13TeV withlarger data sets are expected to have better statistical precision outweighing the dilution ofthe charge asymmetry from the decreased fractionof eventswiththequark–antiquarkinitialstate.

Acknowledgements

We would like to thank W. Bernreuther andZ.-G. Si for cal-culating the theoretical distributions shown in this paper. We congratulate our colleagues in the CERN acceleratordepartments for the excellent performance of the LHC andthank the techni-cal andadministrativestaffs atCERNandatother CMSinstitutes for their contributions to the successof the CMSeffort. In addi-tion, we gratefully acknowledge the computing centres and per-sonnel of the Worldwide LHC Computing Grid for delivering so effectively thecomputinginfrastructure essentialto our analyses. Finally, we acknowledge the enduring support for the construc-tion andoperationofthe LHCandtheCMSdetectorprovided by thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES(Bulgaria);CERN;CAS,MOST,andNSFC(China);COLCIENCIAS (Colombia);MSESandCSF(Croatia);RPF(Cyprus);MoER,ERCIUT andERDF(Estonia); AcademyofFinland,MEC,andHIP (Finland); CEA andCNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE andUM (Malaysia); CINVESTAV, CONACYT,SEP,andUASLP-FAI(Mexico);MBIE(NewZealand);PAEC (Pakistan);MSHEandNSC(Poland);FCT(Portugal);JINR(Dubna); MON,RosAtom,RASandRFBR(Russia);MESTD(Serbia);SEIDIand CPAN(Spain);SwissFundingAgencies(Switzerland);MST(Taipei); ThEPCenter,IPST, STARandNSTDA(Thailand);TÜBITAK andTAEK (Turkey);NASU andSFFR (Ukraine);STFC(United Kingdom);DOE andNSF(USA).Individuals havereceivedsupportfromthe

Marie-Fig. 2. Dependenceofthett andleptonicchargeasymmetriesAC(left)andAlepC (right)obtainedfromtheunfoldeddistributionsindata(points)onMtt(upper),|ytt|(middle),

andptt

T (lower).Parton-levelpredictionsfromthe mc@nlo simulationandcalculationsatNLO(QCD+EW)[12]areshownbydashedandsolidhistograms,respectively.The

verticalbarsshowthetotaluncertainty,thestatisticalcomponentofwhichismarkedbyahorizontal tick.Thelastbinofeachplotincludesoverflowevents.

CurieprogrammeandtheEuropeanResearchCouncilandEPLANET (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation;theAlexandervonHumboldtFoundation;theBelgian Federal Science Policy Office; the Fonds pour la Formation à la Recherchedansl’Industrieetdansl’Agriculture(FRIA-Belgium);the AgentschapvoorInnovatiedoorWetenschapenTechnologie (IWT-Belgium);the Ministryof Education,Youth andSports(MEYS) of theCzechRepublic;theCouncilofScienceandIndustrialResearch, India; the HOMING PLUS programmeof the Foundation for Pol-ish Science, cofinanced from European Union, Regional Develop-ment Fund; the OPUS programme of the National Science Cen-ter(Poland);the Compagnia diSan Paolo (Torino); MIURproject 20108T4XTM (Italy); the Thalis and Aristeia programmes cofi-nancedbyEU-ESFandtheGreekNSRF;theNationalPriorities Re-searchProgrambyQatarNationalResearchFund;theRachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn Univer-sity(Thailand);theChulalongkorn Academicinto Its2nd Century

Project Advancement Project (Thailand); and the Welch Founda-tion,contractC-1845.

Appendix A. Supplementarymaterial

Supplementarymaterialrelatedtothisarticlecanbefound on-lineathttp://dx.doi.org/10.1016/j.physletb.2016.07.006.

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W. Adam, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Erö,M. Flechl, M. Friedl,

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V. Mossolov,N. Shumeiko,J. Suarez Gonzalez

NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

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UniversiteitAntwerpen,Antwerpen,Belgium

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A. Aleksandrov, R. Hadjiiska, P. Iaydjiev,M. Rodozov, S. Stoykova, G. Sultanov, M. Vutova

InstituteforNuclearResearchandNuclearEnergy,Sofia,Bulgaria

A. Dimitrov, I. Glushkov,L. Litov, B. Pavlov,P. Petkov

UniversityofSofia,Sofia,Bulgaria

W. Fang6

BeihangUniversity,Beijing,China

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InstituteofHighEnergyPhysics,Beijing,China

C. Asawatangtrakuldee, Y. Ban, Q. Li, S. Liu,Y. Mao, S.J. Qian, D. Wang,Z. Xu

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

C. Avila,A. Cabrera, L.F. Chaparro Sierra, C. Florez, J.P. Gomez, B. Gomez Moreno,J.C. Sanabria

UniversidaddeLosAndes,Bogota,Colombia

N. Godinovic, D. Lelas, I. Puljak,P.M. Ribeiro Cipriano

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic, M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,K. Kadija, J. Luetic, S. Micanovic,L. Sudic

A. Attikis, G. Mavromanolakis,J. Mousa, C. Nicolaou, F. Ptochos,P.A. Razis, H. Rykaczewski

UniversityofCyprus,Nicosia,Cyprus

M. Finger8,M. Finger Jr.8

CharlesUniversity,Prague,CzechRepublic

E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador

Y. Assran9,10, A. Ellithi Kamel11, A. Mahrous12,A. Radi10,13

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

B. Calpas,M. Kadastik, M. Murumaa, M. Raidal, A. Tiko,C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,J. Pekkanen, M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Härkönen,V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini,S. Lehti, T. Lindén,P. Luukka,

T. Peltola,J. Tuominiemi,E. Tuovinen, L. Wendland

HelsinkiInstituteofPhysics,Helsinki,Finland

J. Talvitie,T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon,F. Couderc, M. Dejardin, D. Denegri,B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour,

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A. Rosowsky,M. Titov, A. Zghiche

DSM/IRFU,CEA/Saclay,Gif-sur-Yvette,France

A. Abdulsalam,I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro, E. Chapon,C. Charlot,

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C. Ochando,G. Ortona, P. Paganini,P. Pigard, S. Regnard,R. Salerno, Y. Sirois,T. Strebler, Y. Yilmaz,A. Zabi

LaboratoireLeprince-Ringuet,EcolePolytechnique,IN2P3–CNRS,Palaiseau,France

J.-L. Agram14,J. Andrea, A. Aubin,D. Bloch, J.-M. Brom,M. Buttignol, E.C. Chabert,N. Chanon, C. Collard,

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K. Skovpen,P. Van Hove

InstitutPluridisciplinaireHubertCurien,UniversitédeStrasbourg,UniversitédeHauteAlsaceMulhouse,CNRS/IN2P3,Strasbourg,France

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

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UniversitédeLyon,UniversitéClaudeBernardLyon1,CNRS–IN2P3,InstitutdePhysiqueNucléairedeLyon,Villeurbanne,France

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Z. Tsamalaidze8

TbilisiStateUniversity,Tbilisi,Georgia

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RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

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RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

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D. Eckstein, T. Eichhorn, E. Gallo19,J. Garay Garcia, A. Geiser, A. Gizhko, P. Gunnellini, J. Hauk,

M. Hempel20,H. Jung, A. Kalogeropoulos, O. Karacheban20, M. Kasemann,P. Katsas, J. Kieseler,

C. Kleinwort,I. Korol, W. Lange, J. Leonard,K. Lipka, A. Lobanov, W. Lohmann20,R. Mankel,

I.-A. Melzer-Pellmann,A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, A. Nayak,E. Ntomari,D. Pitzl,

R. Placakyte, A. Raspereza,B. Roland, M.Ö. Sahin,P. Saxena, T. Schoerner-Sadenius,C. Seitz, S. Spannagel,

N. Stefaniuk, K.D. Trippkewitz,G.P. Van Onsem, R. Walsh, C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

V. Blobel, M. Centis Vignali, A.R. Draeger,T. Dreyer, J. Erfle,E. Garutti, K. Goebel, D. Gonzalez, M. Görner,

J. Haller, M. Hoffmann,R.S. Höing, A. Junkes, R. Klanner, R. Kogler,N. Kovalchuk, T. Lapsien, T. Lenz,

I. Marchesini, D. Marconi,M. Meyer, M. Niedziela, D. Nowatschin, J. Ott, F. Pantaleo15,T. Peiffer,

A. Perieanu, N. Pietsch,J. Poehlsen,C. Sander, C. Scharf, P. Schleper, E. Schlieckau, A. Schmidt,

S. Schumann,J. Schwandt, V. Sola,H. Stadie, G. Steinbrück, F.M. Stober,H. Tholen, D. Troendle,E. Usai,

L. Vanelderen,A. Vanhoefer, B. Vormwald

UniversityofHamburg,Hamburg,Germany

C. Barth,C. Baus, J. Berger,C. Böser, E. Butz, T. Chwalek, F. Colombo, W. De Boer, A. Descroix,

A. Dierlamm, S. Fink,F. Frensch, R. Friese,M. Giffels, A. Gilbert,D. Haitz, F. Hartmann15,S.M. Heindl,

U. Husemann,I. Katkov16,A. Kornmayer15,P. Lobelle Pardo, B. Maier, H. Mildner, M.U. Mozer, T. Müller,

Th. Müller, M. Plagge, G. Quast, K. Rabbertz,S. Röcker, F. Roscher, M. Schröder,G. Sieber, H.J. Simonis,

R. Ulrich, J. Wagner-Kuhr, S. Wayand,M. Weber, T. Weiler, S. Williamson, C. Wöhrmann, R. Wolf

InstitutfürExperimentelleKernphysik,Karlsruhe,Germany

G. Anagnostou, G. Daskalakis,T. Geralis,V.A. Giakoumopoulou, A. Kyriakis, D. Loukas, A. Psallidas,

I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

A. Agapitos, S. Kesisoglou, A. Panagiotou, N. Saoulidou, E. Tziaferi

I. Evangelou,G. Flouris, C. Foudas, P. Kokkas, N. Loukas, N. Manthos,I. Papadopoulos, E. Paradas, J. Strologas

UniversityofIoánnina,Ioánnina,Greece

G. Bencze,C. Hajdu, P. Hidas,D. Horvath21, F. Sikler,V. Veszpremi, G. Vesztergombi22, A.J. Zsigmond

WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni,S. Czellar, J. Karancsi23,J. Molnar, Z. Szillasi

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

M. Bartók22,A. Makovec,P. Raics, Z.L. Trocsanyi, B. Ujvari

UniversityofDebrecen,Debrecen,Hungary

S. Choudhury24,P. Mal, K. Mandal, D.K. Sahoo, N. Sahoo,S.K. Swain

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

S. Bansal,S.B. Beri, V. Bhatnagar, R. Chawla, R. Gupta,U. Bhawandeep, A.K. Kalsi, A. Kaur, M. Kaur,

R. Kumar,A. Mehta,M. Mittal, J.B. Singh, G. Walia

PanjabUniversity,Chandigarh,India

Ashok Kumar,A. Bhardwaj, B.C. Choudhary, R.B. Garg,S. Keshri, A. Kumar,S. Malhotra, M. Naimuddin,

N. Nishu, K. Ranjan,R. Sharma, V. Sharma

UniversityofDelhi,Delhi,India

R. Bhattacharya,S. Bhattacharya, K. Chatterjee, S. Dey,S. Dutta, S. Ghosh, N. Majumdar, A. Modak,

K. Mondal, S. Mukhopadhyay, S. Nandan,A. Purohit, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar,

M. Sharan

SahaInstituteofNuclearPhysics,Kolkata,India

R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty15,L.M. Pant, P. Shukla, A. Topkar

BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz,S. Banerjee, S. Bhowmik25, R.M. Chatterjee, R.K. Dewanjee,S. Dugad, S. Ganguly, S. Ghosh,

M. Guchait,A. Gurtu26, Sa. Jain, G. Kole, S. Kumar,B. Mahakud, M. Maity25,G. Majumder, K. Mazumdar,

S. Mitra, G.B. Mohanty, B. Parida,T. Sarkar25,N. Sur, B. Sutar, N. Wickramage27

TataInstituteofFundamentalResearch,Mumbai,India

S. Chauhan,S. Dube, A. Kapoor, K. Kothekar, A. Rane, S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

H. Bakhshiansohi,H. Behnamian,S.M. Etesami28, A. Fahim29, M. Khakzad, M. Mohammadi Najafabadi,

M. Naseri, S. Paktinat Mehdiabadi,F. Rezaei Hosseinabadi, B. Safarzadeh30, M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, C. Calabriaa,b, C. Caputoa,b, A. Colaleoa,D. Creanzaa,c, L. Cristellaa,b,N. De Filippisa,c,

M. De Palmaa,b, L. Fiorea, G. Iasellia,c, G. Maggia,c, M. Maggia,G. Minielloa,b,S. Mya,b,S. Nuzzoa,b,

A. Pompilia,b, G. Pugliesea,c,R. Radognaa,b,A. Ranieria, G. Selvaggia,b, L. Silvestrisa,15,R. Vendittia,b

b_{UniversitàdiBari,Bari,Italy} c_{PolitecnicodiBari,Bari,Italy}

G. Abbiendia,C. Battilana15, D. Bonacorsia,b, S. Braibant-Giacomellia,b,L. Brigliadoria,b,

R. Campaninia,b, P. Capiluppia,b,A. Castroa,b,F.R. Cavalloa, S.S. Chhibraa,b, G. Codispotia,b,

M. Cuffiania,b,G.M. Dallavallea,F. Fabbria,A. Fanfania,b,D. Fasanellaa,b, P. Giacomellia, C. Grandia,

L. Guiduccia,b,S. Marcellinia,G. Masettia,A. Montanaria,F.L. Navarriaa,b, A. Perrottaa,A.M. Rossia,b,

T. Rovellia,b,G.P. Sirolia,b,N. Tosia,b,15

a_{INFNSezionediBologna,Bologna,Italy} b_{UniversitàdiBologna,Bologna,Italy}

G. Cappellob,M. Chiorbolia,b,S. Costaa,b,A. Di Mattiaa,F. Giordanoa,b,R. Potenzaa,b, A. Tricomia,b,

C. Tuvea,b

a_{INFNSezionediCatania,Catania,Italy} b_{UniversitàdiCatania,Catania,Italy}

G. Barbaglia, V. Ciullia,b,C. Civininia, R. D’Alessandroa,b,E. Focardia,b,V. Goria,b, P. Lenzia,b,

M. Meschinia, S. Paolettia,G. Sguazzonia,L. Viliania,b,15

a_{INFNSezionediFirenze,Firenze,Italy} b_{UniversitàdiFirenze,Firenze,Italy}

L. Benussi, S. Bianco, F. Fabbri,D. Piccolo, F. Primavera15

INFNLaboratoriNazionalidiFrascati,Frascati,Italy

V. Calvellia,b, F. Ferroa, M. Lo Veterea,b, M.R. Mongea,b,E. Robuttia,S. Tosia,b

a_{INFNSezionediGenova,Genova,Italy} b_{UniversitàdiGenova,Genova,Italy}

L. Brianza,M.E. Dinardoa,b, S. Fiorendia,b,S. Gennaia,R. Gerosaa,b,A. Ghezzia,b, P. Govonia,b,

S. Malvezzia, R.A. Manzonia,b,15, B. Marzocchia,b,D. Menascea,L. Moronia,M. Paganonia,b,D. Pedrinia,

S. Pigazzini,S. Ragazzia,b,N. Redaellia, T. Tabarelli de Fatisa,b

a_{INFNSezionediMilano-Bicocca,Milano,Italy} b_{UniversitàdiMilano-Bicocca,Milano,Italy}

S. Buontempoa, N. Cavalloa,c, S. Di Guidaa,d,15, M. Espositoa,b, F. Fabozzia,c,A.O.M. Iorioa,b,G. Lanzaa,

L. Listaa,S. Meolaa,d,15,M. Merolaa,P. Paoluccia,15,C. Sciaccaa,b,F. Thyssen

a_{INFNSezionediNapoli,Napoli,Italy} b_{UniversitàdiNapoli‘FedericoII’,Napoli,Italy} c_{UniversitàdellaBasilicata,Potenza,Italy} d_{UniversitàG.Marconi,Roma,Italy}

P. Azzia,15, N. Bacchettaa, L. Benatoa,b,D. Biselloa,b, A. Bolettia,b,R. Carlina,b,P. Checchiaa,

M. Dall’Ossoa,b,15,T. Dorigoa,U. Dossellia, F. Gasparinia,b, U. Gasparinia,b,F. Gonellaa,A. Gozzelinoa,

S. Lacapraraa,M. Margonia,b,A.T. Meneguzzoa,b,F. Montecassianoa, M. Passaseoa,J. Pazzinia,b,15,

N. Pozzobona,b,P. Ronchesea,b, F. Simonettoa,b,E. Torassaa,M. Tosia,b,M. Zanetti,P. Zottoa,b,

A. Zucchettaa,b,15,G. Zumerlea,b

a_{INFNSezionediPadova,Padova,Italy} b_{UniversitàdiPadova,Padova,Italy} c_{UniversitàdiTrento,Trento,Italy}

A. Braghieria,A. Magnania,b, P. Montagnaa,b,S.P. Rattia,b, V. Rea, C. Riccardia,b,P. Salvinia,I. Vaia,b,

P. Vituloa,b

a_{INFNSezionediPavia,Pavia,Italy} b_{UniversitàdiPavia,Pavia,Italy}

L. Alunni Solestizia,b, G.M. Bileia,D. Ciangottinia,b,L. Fanòa,b, P. Laricciaa,b, R. Leonardia,b,

G. Mantovania,b, M. Menichellia,A. Sahaa,A. Santocchiaa,b

a_{INFNSezionediPerugia,Perugia,Italy} b_{UniversitàdiPerugia,Perugia,Italy}

K. Androsova,31,P. Azzurria,15,G. Bagliesia,J. Bernardinia,T. Boccalia,R. Castaldia, M.A. Cioccia,31,

R. Dell’Orsoa,S. Donatoa,c,G. Fedi, L. Foàa,c,†, A. Giassia, M.T. Grippoa,31,F. Ligabuea,c, T. Lomtadzea,

L. Martinia,b,A. Messineoa,b,F. Pallaa, A. Rizzia,b, A. Savoy-Navarroa,32, P. Spagnoloa, R. Tenchinia,

G. Tonellia,b,A. Venturia, P.G. Verdinia

a_{INFNSezionediPisa,Pisa,Italy} b_{UniversitàdiPisa,Pisa,Italy}

c_{ScuolaNormaleSuperiorediPisa,Pisa,Italy}

L. Baronea,b, F. Cavallaria,G. D’imperioa,b,15, D. Del Rea,b,15,M. Diemoza,S. Gellia,b,C. Jordaa,

E. Longoa,b, F. Margarolia,b, P. Meridiania,G. Organtinia,b, R. Paramattia,F. Preiatoa,b, S. Rahatloua,b,

C. Rovellia,F. Santanastasioa,b

a_{INFNSezionediRoma,Roma,Italy} b_{UniversitàdiRoma,Roma,Italy}

N. Amapanea,b,R. Arcidiaconoa,c,15,S. Argiroa,b,M. Arneodoa,c,R. Bellana,b, C. Biinoa, N. Cartigliaa,

M. Costaa,b,R. Covarellia,b, A. Deganoa,b, N. Demariaa,L. Fincoa,b,B. Kiania,b, C. Mariottia, S. Masellia,

E. Migliorea,b,V. Monacoa,b, E. Monteila,b,M.M. Obertinoa,b,L. Pachera,b,N. Pastronea, M. Pelliccionia,

G.L. Pinna Angionia,b,F. Raveraa,b,A. Romeroa,b,M. Ruspaa,c, R. Sacchia,b, A. Solanoa,b, A. Staianoa

a_{INFNSezionediTorino,Torino,Italy} b_{UniversitàdiTorino,Torino,Italy}

c_{UniversitàdelPiemonteOrientale,Novara,Italy}

S. Belfortea,V. Candelisea,b, M. Casarsaa,F. Cossuttia,G. Della Riccaa,b,B. Gobboa,C. La Licataa,b,

A. Schizzia,b,A. Zanettia

a_{INFNSezionediTrieste,Trieste,Italy} b_{UniversitàdiTrieste,Trieste,Italy}

S.K. Nam

KangwonNationalUniversity,Chunchon,RepublicofKorea

D.H. Kim,G.N. Kim, M.S. Kim, D.J. Kong, S. Lee, S.W. Lee, Y.D. Oh,A. Sakharov, D.C. Son

KyungpookNationalUniversity,Daegu,RepublicofKorea

J.A. Brochero Cifuentes,H. Kim, T.J. Kim33

ChonbukNationalUniversity,Jeonju,RepublicofKorea

S. Song

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

S. Cho,S. Choi, Y. Go, D. Gyun,B. Hong, H. Kim,Y. Kim,B. Lee, K. Lee, K.S. Lee, S. Lee, J. Lim, S.K. Park,

Y. Roh

KoreaUniversity,Seoul,RepublicofKorea

H.D. Yoo

SeoulNationalUniversity,Seoul,RepublicofKorea

M. Choi,H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park, G. Ryu, M.S. Ryu

Y. Choi,J. Goh, D. Kim, E. Kwon, J. Lee,I. Yu

SungkyunkwanUniversity,Suwon,RepublicofKorea

V. Dudenas, A. Juodagalvis,J. Vaitkus

VilniusUniversity,Vilnius,Lithuania

I. Ahmed,Z.A. Ibrahim, J.R. Komaragiri, M.A.B. Md Ali34,F. Mohamad Idris35,W.A.T. Wan Abdullah,

M.N. Yusli,Z. Zolkapli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

E. Casimiro Linares, H. Castilla-Valdez, E. De La Cruz-Burelo,I. Heredia-De La Cruz36,

A. Hernandez-Almada,R. Lopez-Fernandez, J. Mejia Guisao, A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, F. Vazquez Valencia

UniversidadIberoamericana,MexicoCity,Mexico

I. Pedraza, H.A. Salazar Ibarguen

BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico

A. Morelos Pineda

UniversidadAutónomadeSanLuisPotosí,SanLuisPotosí,Mexico

D. Krofcheck

UniversityofAuckland,Auckland,NewZealand

P.H. Butler

UniversityofCanterbury,Christchurch,NewZealand

A. Ahmad, M. Ahmad, Q. Hassan,H.R. Hoorani, W.A. Khan, T. Khurshid,M. Shoaib, M. Waqas

NationalCentreforPhysics,Quaid-I-AzamUniversity,Islamabad,Pakistan

H. Bialkowska, M. Bluj,B. Boimska, T. Frueboes,M. Górski, M. Kazana, K. Nawrocki,

K. Romanowska-Rybinska, M. Szleper,P. Traczyk,P. Zalewski

NationalCentreforNuclearResearch,Swierk,Poland

G. Brona, K. Bunkowski, A. Byszuk37,K. Doroba, A. Kalinowski, M. Konecki,J. Krolikowski, M. Misiura,

M. Olszewski, M. Walczak

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

P. Bargassa,C. Beirão Da Cruz E Silva, A. Di Francesco, P. Faccioli, P.G. Ferreira Parracho,M. Gallinaro,

J. Hollar, N. Leonardo,L. Lloret Iglesias, M.V. Nemallapudi, F. Nguyen, J. Rodrigues Antunes, J. Seixas,

O. Toldaiev, D. Vadruccio,J. Varela, P. Vischia

LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal

I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, V. Korenkov,A. Lanev, A. Malakhov, V. Matveev38,39,

V.V. Mitsyn,P. Moisenz, V. Palichik, V. Perelygin, S. Shmatov, S. Shulha,N. Skatchkov, V. Smirnov,

E. Tikhonenko, N. Voytishin, A. Zarubin

V. Golovtsov,Y. Ivanov, V. Kim40,E. Kuznetsova, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov,

V. Sulimov,L. Uvarov, S. Vavilov, A. Vorobyev

PetersburgNuclearPhysicsInstitute,Gatchina(St.Petersburg),Russia

Yu. Andreev,A. Dermenev,S. Gninenko, N. Golubev, A. Karneyeu, M. Kirsanov,N. Krasnikov,

A. Pashenkov,D. Tlisov, A. Toropin

InstituteforNuclearResearch,Moscow,Russia

V. Epshteyn,V. Gavrilov, N. Lychkovskaya,V. Popov, I. Pozdnyakov,G. Safronov, A. Spiridonov, E. Vlasov,

A. Zhokin

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia

M. Chadeeva,R. Chistov, M. Danilov,O. Markin, E. Tarkovskii

NationalResearchNuclearUniversity‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

V. Andreev,M. Azarkin39,I. Dremin39, M. Kirakosyan, A. Leonidov39,G. Mesyats, S.V. Rusakov

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,V. Bunichev, M. Dubinin41, L. Dudko, A. Ershov, V. Klyukhin,

O. Kodolova,N. Korneeva,I. Lokhtin, I. Miagkov, S. Obraztsov,M. Perfilov, V. Savrin

SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,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

StateResearchCenterofRussianFederation,InstituteforHighEnergyPhysics,Protvino,Russia

P. Adzic42,P. Cirkovic, D. Devetak,J. Milosevic,V. Rekovic

UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia

J. Alcaraz Maestre,E. Calvo, M. Cerrada,M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris,

A. Escalante Del Valle,C. Fernandez Bedoya, J.P. Fernández Ramos,J. Flix, M.C. Fouz,P. Garcia-Abia,

O. Gonzalez Lopez,S. Goy Lopez, J.M. Hernandez, M.I. Josa, E. Navarro De Martino,

A. Pérez-Calero Yzquierdo,J. Puerta Pelayo, A. Quintario Olmeda,I. Redondo, L. Romero,M.S. Soares

CentrodeInvestigacionesEnergéticasMedioambientalesyTecnológicas(CIEMAT),Madrid,Spain

J.F. de Trocóniz,M. Missiroli, D. Moran

UniversidadAutónomadeMadrid,Madrid,Spain

J. Cuevas,J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero,E. Palencia Cortezon15,

J.M. Vizan Garcia

UniversidaddeOviedo,Oviedo,Spain

I.J. Cabrillo, A. Calderon, J.R. Castiñeiras De Saa, E. Curras, P. De Castro Manzano,M. Fernandez,

J. Garcia-Ferrero,G. Gomez, A. Lopez Virto, J. Marco,R. Marco, C. Martinez Rivero,F. Matorras,

J. Piedra Gomez,T. Rodrigo, A.Y. Rodríguez-Marrero,A. Ruiz-Jimeno, L. Scodellaro, N. Trevisani,I. Vila,

R. Vilar Cortabitarte

InstitutodeFísicadeCantabria(IFCA),CSIC–UniversidaddeCantabria,Santander,Spain

D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis,P. Baillon, A.H. Ball, D. Barney, A. Benaglia,L. Benhabib,

G.M. Berruti,P. Bloch, A. Bocci, A. Bonato, C. Botta, H. Breuker, T. Camporesi, R. Castello, M. Cepeda,

A. De Roeck, E. Di Marco43,M. Dobson, M. Dordevic, B. Dorney, T. du Pree,D. Duggan, M. Dünser,

N. Dupont,A. Elliott-Peisert, G. Franzoni, J. Fulcher, W. Funk, D. Gigi, K. Gill,M. Girone, F. Glege,

R. Guida, S. Gundacker, M. Guthoff,J. Hammer, P. Harris, J. Hegeman, V. Innocente, P. Janot,

H. Kirschenmann,V. Knünz, M.J. Kortelainen, K. Kousouris,P. Lecoq, C. Lourenço,M.T. Lucchini,

N. Magini,L. Malgeri, M. Mannelli,A. Martelli, L. Masetti,F. Meijers, S. Mersi, E. Meschi, F. Moortgat,

S. Morovic, M. Mulders, H. Neugebauer,S. Orfanelli44, L. Orsini,L. Pape, E. Perez, M. Peruzzi,A. Petrilli,

G. Petrucciani,A. Pfeiffer, M. Pierini,D. Piparo, A. Racz,T. Reis, G. Rolandi45,M. Rovere, M. Ruan,

H. Sakulin, J.B. Sauvan, C. Schäfer, C. Schwick,M. Seidel, A. Sharma,P. Silva, M. Simon, P. Sphicas46,

J. Steggemann,M. Stoye, Y. Takahashi, D. Treille, A. Triossi,A. Tsirou, V. Veckalns47,G.I. Veres22,

N. Wardle,H.K. Wöhri, A. Zagozdzinska37, W.D. Zeuner

CERN,EuropeanOrganizationforNuclearResearch,Geneva,Switzerland

W. Bertl,K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski,U. Langenegger,

T. Rohe

PaulScherrerInstitut,Villigen,Switzerland

F. Bachmair, L. Bäni, L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Donegà, P. Eller, C. Grab,

C. Heidegger, D. Hits, J. Hoss,G. Kasieczka, P. Lecomte†, W. Lustermann,B. Mangano, M. Marionneau,

P. Martinez Ruiz del Arbol, M. Masciovecchio, M.T. Meinhard,D. Meister,F. Micheli, P. Musella,

F. Nessi-Tedaldi, F. Pandolfi, J. Pata, F. Pauss,G. Perrin, L. Perrozzi,M. Quittnat, M. Rossini,

M. Schönenberger, A. Starodumov48,M. Takahashi, V.R. Tavolaro, K. Theofilatos,R. Wallny

InstituteforParticlePhysics,ETHZurich,Zurich,Switzerland

T.K. Aarrestad, C. Amsler49, L. Caminada,M.F. Canelli, V. Chiochia,A. De Cosa, C. Galloni, A. Hinzmann,

T. Hreus, B. Kilminster,C. Lange, J. Ngadiuba, D. Pinna,G. Rauco, P. Robmann, D. Salerno, Y. Yang

UniversitätZürich,Zurich,Switzerland

K.H. Chen, T.H. Doan,Sh. Jain, R. Khurana,M. Konyushikhin, C.M. Kuo, W. Lin, Y.J. Lu, A. Pozdnyakov,

S.S. Yu

NationalCentralUniversity,Chung-Li,Taiwan

Arun Kumar, P. Chang, Y.H. Chang,Y.W. Chang, Y. Chao, K.F. Chen, P.H. Chen, C. Dietz,F. Fiori,

U. Grundler,W.-S. Hou, Y. Hsiung, Y.F. Liu,R.-S. Lu, M. Miñano Moya,E. Petrakou, J.f. Tsai, Y.M. Tzeng

NationalTaiwanUniversity(NTU),Taipei,Taiwan

B. Asavapibhop, K. Kovitanggoon, G. Singh, N. Srimanobhas,N. Suwonjandee

ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

A. Adiguzel, M.N. Bakirci50, S. Damarseckin, Z.S. Demiroglu, C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis,

G. Gokbulut, Y. Guler, E. Gurpinar,I. Hos, E.E. Kangal51,G. Onengut52,K. Ozdemir53, A. Polatoz,

D. Sunar Cerci54,B. Tali54, C. Zorbilmez

CukurovaUniversity,Adana,Turkey

B. Bilin, S. Bilmis, B. Isildak55, G. Karapinar56, M. Yalvac, M. Zeyrek

MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E. Gülmez,M. Kaya57,O. Kaya58, E.A. Yetkin59, T. Yetkin60

BogaziciUniversity,Istanbul,Turkey

A. Cakir,K. Cankocak, S. Sen61,F.I. Vardarlı

B. Grynyov

InstituteforScintillationMaterialsofNationalAcademyofScienceofUkraine,Kharkov,Ukraine

L. Levchuk,P. Sorokin

NationalScientificCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine

R. Aggleton,F. Ball, L. Beck, J.J. Brooke, D. Burns,E. Clement, D. Cussans, H. Flacher,J. Goldstein,

M. Grimes, G.P. Heath, H.F. Heath,J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold62,

S. Paramesvaran,A. Poll, T. Sakuma,S. Seif El Nasr-storey, S. Senkin, D. Smith,V.J. Smith

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell,A. Belyaev63,C. Brew, R.M. Brown, L. Calligaris,D. Cieri, D.J.A. Cockerill, J.A. Coughlan,

K. Harder,S. Harper, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea,I.R. Tomalin, T. Williams,

S.D. Worm

RutherfordAppletonLaboratory,Didcot,UnitedKingdom

M. Baber,R. Bainbridge, O. Buchmuller, A. Bundock,D. Burton, S. Casasso,M. Citron, D. Colling, L. Corpe,

P. Dauncey,G. Davies, A. De Wit, M. Della Negra, P. Dunne, A. Elwood, D. Futyan,Y. Haddad, G. Hall,

G. Iles, R. Lane,R. Lucas62,L. Lyons, A.-M. Magnan, S. Malik, L. Mastrolorenzo,J. Nash, A. Nikitenko48,

J. Pela, B. Penning,M. Pesaresi, D.M. Raymond, A. Richards,A. Rose, C. Seez,A. Tapper, K. Uchida,

M. Vazquez Acosta64, T. Virdee15, S.C. Zenz

ImperialCollege,London,UnitedKingdom

J.E. Cole, P.R. Hobson,A. Khan, P. Kyberd,D. Leslie, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner

BrunelUniversity,Uxbridge,UnitedKingdom

A. Borzou,K. Call,J. Dittmann, K. Hatakeyama, H. Liu, N. Pastika

BaylorUniversity,Waco,USA

O. Charaf,S.I. Cooper, C. Henderson, P. Rumerio

TheUniversityofAlabama,Tuscaloosa,USA

D. Arcaro, A. Avetisyan, T. Bose,D. Gastler, D. Rankin, C. Richardson,J. Rohlf, L. Sulak,D. Zou

BostonUniversity,Boston,USA

J. Alimena,G. Benelli, E. Berry, D. Cutts, A. Ferapontov, A. Garabedian,J. Hakala, U. Heintz, O. Jesus,

E. Laird,G. Landsberg, Z. Mao, M. Narain, S. Piperov,S. Sagir, R. Syarif

BrownUniversity,Providence,USA

R. Breedon,G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan,M. Chertok, J. Conway, R. Conway,

P.T. Cox,R. Erbacher, G. Funk, M. Gardner,W. Ko, R. Lander, C. Mclean,M. Mulhearn, D. Pellett,J. Pilot,

F. Ricci-Tam,S. Shalhout, J. Smith, M. Squires, D. Stolp, M. Tripathi,S. Wilbur, R. Yohay

UniversityofCalifornia,Davis,Davis,USA

R. Cousins,P. Everaerts, A. Florent, J. Hauser,M. Ignatenko, D. Saltzberg, E. Takasugi,V. Valuev, M. Weber

UniversityofCalifornia,LosAngeles,USA

K. Burt,R. Clare, J. Ellison, J.W. Gary, G. Hanson,J. Heilman, M. Ivova PANEVA, P. Jandir, E. Kennedy,

F. Lacroix,O.R. Long, M. Malberti,M. Olmedo Negrete, A. Shrinivas, H. Wei,S. Wimpenny, B.R. Yates