Search for leptophobic Z′ bosons decaying into four-lepton final states in proton–proton collisions at √s = 8 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

leptophobic

Z



bosons

decaying

into

four-lepton

final

states

in

proton–proton

collisions

at

√

s

=

8

TeV

.TheCMS Collaboration CERN,Switzerland

a r t i c l e i n f o a b s t ra c t

Articlehistory: Received5January2017

Receivedinrevisedform30April2017 Accepted24August2017

Availableonline6September2017 Editor:M.Doser Keywords: LHC CMS Physics Exotica Z Fourleptons

Asearchforheavynarrowresonancesdecayingintofour-leptonfinalstateshasbeenperformedusing proton–proton collision data at √s=8TeV collected by the CMS experiment, corresponding to an integratedluminosityof19.7 fb−1_{.Noexcessofeventsoverthestandardmodelbackgroundexpectation} isobserved.Upperlimitsforabenchmarkmodelontheproductofcrosssectionandbranchingfraction forthe productionoftheseheavynarrowresonances arepresented.The limitexcludesleptophobicZ bosonswithmassesbelow2.5 TeV withinthebenchmarkmodel.Thisisthefirstresult toconstraina leptophobicZresonanceinthefour-leptonchannel.

©2017TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Extensionsofthestandardmodel(SM)thatincorporateoneor moreextra Abeliangauge groups predictthe existence ofone or more neutral gauge bosons [1,2]. These occur naturally in most grandunifiedtheories.Heavyneutralbosonsarealsopredictedin modelswithextraspatial dimensions[3,4],e.g. Randall–Sundrum models [5,6], where these resonances may arise from Kaluza– Klein excitations of a graviton. Searches for heavy neutral reso-nances at hadron colliders, and most recently atthe CERN LHC, are typically performedusing the dijet [7–10], dilepton [11–14], diphoton [15–17], diboson [18–24], and tt [25–28] final states. The dilepton channel provides a clean signal compared withthe dijetand tt channels. However, in leptophobic Z models, where theZ doesnotcouple toSM leptons, thedileptonlimitsare not applicable. Although searches based on the dijet final state re-mainapplicable,theysufferfromlargedijetbackgroundproduced byquantumchromodynamics(QCD) subprocesses.Weextendthe searchforheavy neutralvector bosonsby consideringpossible Z decaysinto newparticles predicted by various theoretical exten-sionsoftheSM.

InthisLetter, wereportona searchforaleptophobic Z reso-nancethatdecaysintofourleptonsviacascadedecaysasdescribed

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

Fig. 1. LeadingorderFeynmandiagramfortheproductionandcascadedecayofaZ resonancetoafour-leptonfinalstate.

inRef.[29].Inthismodel,theZiscoupledtoquarkpairsbutnot toleptonpairs,andcanbeproducedwithalargecrosssectionat theLHC. Thesenon-standard Z resonances alsodecaytopairs of newscalarbosons(ϕ)eachofwhichsubsequentlydecaystopairs of leptons (ϕ→ , where and=e or μ). Fig. 1 shows the leading-order Feynman diagramfor theproductionoffour-lepton finalstatesviaaZresonanceatahadroncollider.The reconstruc-tion of the ϕ bosons inthe dilepton channel is inefficientif the differencebetweenZand ϕmassesislargeandthetwodaughter leptons are consequently highly collimated. In thefollowing sec-tionswedescribeatechniquetoincreasetheselectionefficiency.

http://dx.doi.org/10.1016/j.physletb.2017.08.069

0370-2693/©2017TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

Theanalysisisasearch forheavynarrowresonancesdecaying into four isolated final state leptons. The benchmark model [29] assumes(/M<1%),corresponding toa naturalwidth ofthe Z resonancethat ismuch smaller thanthe detectorresolution.The followingfinalstatesareconsidered: μμμμ, μμμe, μμee, μeee, andeeee.The μμee, μμμe and μeee channelsareincludedto al-low forthe possibilityof lepton flavor violation(LFV) [30–32] in thedecays ofthe newscalarbosons. InthisLetter, we set limits ontheproductofthecrosssectionandbranchingfractionfor pro-ductionanddecaytofourleptons,andinterprettheresultsinthe contextofthebenchmarkmodeldescribedabove[29].

2. The CMS detector

The central feature of the CMS apparatus is a superconduct-ing solenoidof 6 m internal diameter, providinga magnetic field of3.8 T. Withinthe solenoidvolume area siliconpixel andstrip tracker,aleadtungstatecrystalelectromagneticcalorimeter(ECAL), anda brass andscintillator hadron calorimeter (HCAL).Each de-tector is composed of a barreland two endcap sections. Muons are measured in gas-ionization detectors embedded in the steel flux-returnyokeoutsidethesolenoid.Extensiveforward calorime-trycomplementsthecoverageprovided bythebarrelandendcap detectors.

Muons are measured in the range |η|<2.4 with detection planes made using three technologies: drift tubes, cathode strip chambers,andresistive-platechambers.Matchingmuonstotracks measured inthesilicontrackerresultsin arelative pT resolution formuonswith 20<pT<100GeV of 1.3–2.0%in the barreland better than6% inthe endcaps.The pT resolutionin thebarrelis betterthan10%formuonswithpT upto1 TeV[33].

The ECAL consistsof 75 848 crystals that provide coverage in pseudorapidity|η|<1.48 inabarrelregion(EB)and1.48<|η|<

3.00 in two endcap regions (EE). The electron momentum is es-timatedby combiningtheenergymeasurementin theECALwith themomentummeasurementinthetracker.Themomentum reso-lutionforelectronswithtransversemomentum pT≈45GeV from Z→e+e− decays ranges from 1.7% for nonshowering electrons (approximately 30%) in the barrel region to 4.5% for showering electrons(approximately60%)intheendcaps[34].

AmoredetaileddescriptionoftheCMSdetector,togetherwith adefinitionofthecoordinatesystemused andthe relevant kine-maticvariables,canbefoundinRef.[35].

3. The simulated event samples

TheMonteCarlo(MC)generatorprogram usedtoproducethe simulated event samples for the benchmark model is CalcHEP 3.4.1[36]interfacedwith pythia 6.4.24[37].Thesesamplesare di-videdintofivedecaychannels(μμμμ, μμμe, μμee, μeee,eeee) fordifferentZ bosonmasses(mZ)rangingfrom250to3000 GeV in increments of 250 GeV. The benchmark model assumes that new particles other than Z and ϕ are heavy enough not to af-fecttheproductionanddecayoftheZboson.SignalMC samples are produced withsixdifferentvalues ofthe ϕ mass (mϕ ),with

mϕ=50GeV used as the reference mass value in the interpre-tationof the results.An importantfeature of thisanalysis isthe presenceofa “boostedsignature”associated withthe collimation ofthetwoleptons comingfromthesameparent particleand re-sultingfromthelargedifferencebetweenmZ andmϕ .Inaddition, samplesare generated withmϕ masses of 5,10,20,30 and40% ofmZ,forwhich,inmostcases,thecontributionfromtheboosted signatureis lessimportant.Theproductoftheleading order(LO) signalcrosssection andbranchingfractionineachchannel varies with mZ (from 250 to 3000 GeV) as follows: μμμμ and eeee

from0.8 pb to3.0×10−6_{pb, μμee from12.3 pb to4.7×10}−5_pb, and μμμe and μeee from3.1 pb to1.2×10−5pb.Thebranching fractionof ϕ→ _{issetto1andthereforeonlytheleptonic} de-caychannelsareconsidered.ThesesignalMCsamplesareusedto optimizeeventselection,evaluatesignal efficienciesandcalculate exclusionlimits.

The dominant SM backgroundis the production of ZZ decay-ing intofour leptons.The qq-induced ZZ production isgenerated using the pythia event generator andthe gg-induced production using the gg2zz program [38]. Additional backgrounds from di-boson production(WW and WZ) aregenerated with pythia,and from top quark production (tt, tW, and tW) are generated with powheg1.0[39].Otherprocesses,suchasttZ andtriboson produc-tion(WWγ,WWZ,WZZ,andZZZ),aregeneratedwith MadGraph 5.1.3.30 [40]. Simulated eventsamples are normalized using the integratedluminosity andhigher ordertheoretical crosssections: next-to-next-to-leadingorderfortt[41] andnext-to-leadingorder forZZ[42]andtheotherbackgrounds.

TheMCsamplesaregeneratedusingtheCTEQ6L[43]setof par-ton distributionfunctions(PDFs)andthe pythia Z2*tune [44,45] in ordertomodelthe protonstructureandtheunderlying event. The samples are then processedwith thefull CMS detector sim-ulationsoftware,basedon Geant4[46,47],whichincludestrigger simulationandeventreconstruction.

4. Event selection

The 2012 data set of proton–protoncollisions at √s=8TeV, correspondingtoanintegratedluminosityof19.7 fb−1,isusedfor the analysis. Data are collected withlepton triggers with various

pT thresholds. The trigger used for the muon-enriched channels (μμμμ, μμμe) requiresthepresence ofatleastone muon can-didate with pT>40GeV and |η|<2.1. The trigger used for the electron-enriched channels (μeee,eeee) requires two clusters of energy deposits inthe ECAL withtransverse energy ET>33GeV each.Forthe μμee channel,thetriggerrequiresbothan electron andamuonwithpT>22GeV.

In the subsequent analysis, events are required to contain a reconstructed primary vertex (PV) with at least four associated tracks,anditsr (z)coordinatesarerequiredtobewithin2 (24) cm of thenominalinteraction point.The PVis definedasthevertex withthehighestsumofp2_Tfortheassociatedtracks.Weselectthe eventswithfour leptonsin thefinal state,where theleptons are identifiedby theselectioncriteriadescribed below.The two lead-ing leptons are required to have pT>45GeV to ensure that the trigger is fullyefficient forthe selected events. Thisrequirement hasanegligibleeffectonthesignalacceptance.Thetwo sublead-ingleptonsarerequiredtohavepT>30GeV.Thischoicebalances lossofefficiencyagainstincreasedmisidentificationprobability.All four leptons mustsatisfy |η|<2.4.No charge requirementis ap-pliedtotheleptonselection.

Muoncandidatesarereconstructedbyacombinedfitincluding hits in both tracking andmuon detectors (“global muons”) [33]. The tracksassociatedwithglobalmuonsarerequiredtohavethe following properties: at least one pixel detector hit, at least six strip trackerlayers with hits, at leastone muon chamber hit, at leasttwomuondetectorplaneswithmuonsegments,atransverse impact parameterofthetrackertrack|dxy|<0.2 cm withrespect tothePV,alongitudinaldistanceofthetrackertrack|dz|<0.5 cm withrespecttothePV,andδpT/pT<0.3 whereδpT isthe uncer-tainty inthe measured pT of thetrack. All muon candidates are requiredtobeisolated.Amuonisconsideredisolatedifthescalar

pT sumofalltrackswithinaconeof R<0.3 aroundthemuon, excluding the muon candidate itself,does not exceed10% of the

muon pT,where R=



( φ)2_{+ ( η)}2_{.Ifthereisa second} lep-toncandidatewithinacone R<0.3,weremoveitscontribution. Anelectroncandidateisidentifiedbymatchingaclusterinthe ECAL to a track in the silicon tracker [34]. Identification criteria are applied to suppress jetsmisidentified as electrons. Electrons are required to pass the following criteria:the profile of energy depositionintheECALshouldbeconsistentwithanelectron,the sumofHCAL energydeposits behind the ECALcluster should be lessthan10% oftheassociatedECALdeposit,thetrackassociated withtheclustershouldhavenomorethanonehitmissinginthe pixel detectorlayers and |dxy| should be less than 0.02 cm with respecttotheselectedPV. Allelectroncandidatesarerequiredto beisolatedusingthefollowingdefinition:withinacone R<0.3 aroundthetrackoftheelectroncandidate,thepTsumofallother tracksisrequiredtobelessthan5 GeV andtheETsumofthe en-ergiesofthecalorimeterdepositsthatarenotassociatedwiththe candidateisrequiredtobelessthan5%ofthecandidate’sET.This differsfromthe isolation requirementof3% in Ref.[13],because of the inefficiency (of approximately 6% at electron ET=1TeV) causedbyoverlapping electrons duetothehighLorentz boostof the ϕboson(mϕ=50GeV).Inaddition,ifthedirectionofthe sec-ond lepton candidate falls within the isolation cone of the first ( R<0.3),thecontributionsitmakestobothpTandETare sub-tractedwhenimposingtheisolationrequirements.

Thekinematicdistributions ofthefinal-stateparticlesare sim-ilar for all five channels. The final state consists of two leading leptons withhigh pT andtwo subleading leptons withrelatively low pT. The two leptons from the same parent ϕ boson can be highlyLorentzboostedifmϕ issignificantlysmallerthanmZ.This featureisgenerallyfound forhigh-mass (mZ>1TeV)samplesin thecaseofmϕ=50GeV.Thisboostedsignature introduces a sig-nificantinefficiencyfortheeventselectionexceptfortheLFVcase (ϕ decayingintoeμ).To takeinto accountthe boostedsignature for ϕ decayinginto μμ,one ofthemuon candidatesselected by theabove criteriaisallowedtobereconstructedonlyasatracker muon, a track in the tracker matched to track segments in the muonsystem(“trackermuons”)[33],ifthetwomuonsareasclose as R<0.4.Insuchexceptionalcases,therequirementsofatleast onemuonchamberhitandatleasttwomuondetectorplaneswith muonsegmentsarenotappliedtothetrackermuon.

Theboostedsignature fora ϕ decaying intoee is muchmore complicated since the electrons can easily merge into a single cluster in the ECAL. In this case, only one electron candidate is reconstructedfromthetwo original electrons.The probabilityfor having a merged candidate is about 50% with mZ =3TeV and

mϕ=50GeV. Theseevents wouldbe rejectedby the four-lepton requirement,introducingalargesignal inefficiency.Toselectsuch events,an electron candidate having a ratio of ECAL cluster en-ergytotrackmomentumlarger than1.5andasecond trackwith

pT>30GeV withinaconeof R(electron, track)<0.25,is consid-eredasa“mergedelectron”.Eventsareacceptedwiththree(two) leptons if they contain one (two) merged electron(s), since each mergedelectron is considered tocontribute two electrons to the total.Inorder to avoidsignificant misidentification, merged elec-tronsareonlyconsiderediftheECALclusterenergyisbiggerthan 500 GeV.

ThedominantbackgroundinthisanalysisarisesfromZZ events decaying into four leptons. To suppress this background, events withtwooppositely chargedsame-flavorleptonpairsare rejected ifthemassoftheleptonpair,m,isintherange89–93 GeV.The

Z masswindow is madeas narrow aspossible inorder to min-imisedegradation ofthesignal efficiencyinthe caseofmϕ≈mZ. This requirement results in negligible signal efficiency loss for

mZ>500GeV.At lower masses,the efficiencylossincreases and isapproximately20 (7)% atmZ=250GeV forthe eeee(μμμμ)

channel.Morethan70%(30%)oftheZZ backgroundisrejectedby themasswindow vetorequirementinthe muon(electron) chan-nel.This requirementisnot appliedto themerged electroncase, thus accounting forthe difference in rejection efficiency for the twochannels.

The event selection efficiency is 50–70% (μμμμ), 55–65% (μμμe and μμee) and45–65% (μeee and eeee)throughout the range mZ>1TeV for mϕ=50GeV. Below mZ =1TeV, the effi-ciency decreases rapidly because ofthe effect on the acceptance ofthekinematicrequirements.Heaviermϕ valuescorrespondtoa lessboostedsignatureandthereforeareselectedwithahigher ef-ficiency.FormZ>2 TeV,theefficiencyfortheothermϕ samplesis approximately10–15%(1–5%)higherintheelectron(muon) chan-nelsthanforthemϕ=50GeV scenario,wheretherangeofvalues reflects the variation withmZ. For mZ<1TeV, the contribution fromboostedeventsisnotsignificantandtheefficiencyissimilar forallvaluesofmϕ considered.

5. Background estimation

Mostofthe SMbackgrounds are suppressedby requiringfour isolated high-quality lepton candidates. As discussed above, the dominantbackgroundisfromZZ eventsdecayingintofourleptons. Otherbackgroundsoriginatefromtopquarkeventswithtwo gen-uineleptonsandtwoleptoncandidatesarisingfrommisidentified jets,andfromWW (WZ)eventsthatcontaintwo(one) misidenti-fiedor nonpromptleptons fromjets. Inthecaseof triboson pro-duction, there may be four genuine leptons in the event. These backgroundsareestimatedusingMCsimulation.

Thecontributionfromeventswithmorethantwoleptons aris-ing frommisidentified jets is expected to be small because this analysisrequiresfourisolatedleptonsinthefinal state.This back-groundisestimatedusingthe“misidentificationrate”method de-scribedinRef.[13].Themisidentificationratemeasuredasa func-tion ofelectron ET inthe barrelandendcapis appliedto events withelectroncandidatespassingthetriggerbutfailingthefull se-lection.Thecontributionfromjetbackgroundsestimatedusingthis procedureisfoundtobenegligible.

Fig. 2showsthe four-lepton invariant mass (m4) distribution

forselectedevents.Thenumberofobservedeventsandestimated backgrounds are summarized in Table 1. As shown inthe figure andtable,thedistributionofobservedeventsisinagreementwith the expected backgrounds. The table shows two different mass ranges.In theregionm4>1TeV, thebackgroundsfromSM

pro-cessesareverysmall,typicallylessthanoneevent.

6. Results

No excess ofeventsis observedinthe datasample compared to the SM expectations and exclusion limits at 95% confidence level (CL)are calculated in thecontext of thebenchmark model. The signal region consists of events with four leptons (e or μ) with|η|<2.4: thetwo leading (subleading)leptons are required to have pT>45(30)GeV.ABayesian approach isadoptedwitha likelihoodfunctiondefinedwithasignalstrengthmodifier,aprior probability,andaset ofnuisanceparameters. Theprior probabil-itydistributionforthesignalcrosssectionispositiveanduniform, sincethisisknowntoresultingoodfrequentistcoverage proper-ties.Thesystematicuncertaintiesassociatedwiththebackgrounds, selectionefficiencyandluminosityaretreatedasnuisance param-eterswithlog-normalpriordistributions[48].Alimitonthesignal contributionisderivedbyinterpretingthelikelihoodfunctionasa probability distributionandintegratingover this.The coverage of the95%CLassignedtothelimithasbeencheckedusingaMarkov chainMonteCarlomethod.

Fig. 2. Them4spectrumforthecombinationofthefivestudiedchannels.Thepointswithverticalbarsrepresentthedataandtheassociatedstatisticaluncertainties;the histogramsrepresenttheexpectationsfromSMprocesses;“Topquark”denotesthesumoftheeventsfortt,tW,ttZ processes;“EW”denotesthesumoftheeventsfrom WW, WZ, WWγ, WWZ, WZZ,andZZZ processes.TheinsetshowstheexpectationfromthebenchmarkmodelforasignalatmZ=2.5TeV withmϕ=50GeV.

Table 1

Summaryoftheobservedyieldandexpectedbackgroundsforallchannels,whereNobsisthenumberofobservedevents

indata.Thetotalbackground(Ntot)isthesumofthreedifferentbackgroundsthatareestimatedusingMCsimulations;

NZZreferstothebackgroundfromZZ events;Ntisthebackgroundfromtt,singletopquark,andttZ production;NEWis

thebackgroundfromWW andWZ,andtriplegaugebosonproduction.Thequoteduncertaintiesarestatisticalonly. Channel 0.1<m4<1.0 TeV m4>1.0 TeV

Nobs SM backgrounds Nobs Ntot

NZZ Nt NEW Ntot Z→μμμμ 3 4.9±0.3 0.9±0.5 – 5.9±0.6 0 – Z→μμμe 6 0.4±0.1 1.3±0.6 1.2±0.3 2.9±0.7 0 – Z→μμee 12 9.3±0.4 3.0±1.5 1.2±0.3 13.5±1.6 0 0.1±0.1 Z→μeee 2 0.2±0.1 0.4±0.1 0.6±0.2 1.2±0.2 0 0.1±0.1 Z→eeee 9 15.0±0.5 0.2±0.1 0.2±0.1 15.4±0.5 0 0.2±0.1 Combined 32 29.9±0.7 5.7±1.9 3.3±0.5 38.9±2.1 0 0.4±0.2

Thesystematicuncertaintiesaredominatedbytheuncertainties inthe backgroundestimates andin thelepton selection efficien-cies.TheuncertaintyintheMCestimationofthemainbackground cross section (ZZ and tt) arising from higher-order QCD correc-tions andchoice of PDFsis 15%. In orderto be conservative, we choose to double this figure and assign an uncertainty of 30% fromthissource.Thesystematicuncertaintyinthemuonselection efficiencyincluding reconstruction, identification, and isolation is 0.5% [33]. The uncertainties in the electron selection efficiency are 0.7% (0.6%) for electrons below 100 GeV in EB (EE) and1.4% (0.4%)forelectrons above100 GeV inEB (EE) [13].The uncertain-ties due to the lepton efficiency in both signal and background yields vary between 2.2% and2.7% as a function of m4.

Includ-ing theeffectof themerged leptonsignature, a total uncertainty of10%intheeventselectionefficiencyisassignedforeach chan-nel.Theimpactoftheuncertaintyintheelectronenergyscaleon signal (background) yield is 1% (0.5%) [13]. Uncertainties in the muonmomentumscaleandmassresolutionsarebelow0.1%[33]. Theuncertaintyintheintegratedluminosityisassignedtobe2.6% [49].Inthisanalysis,thestatisticaluncertaintiesaredominantand the systematic uncertainties have a small impact on the results. Wetestedtherobustnessofthelimitsbydoublingthevalues as-sumedforthe systematicuncertainties. Weobserved anegligible

change in the calculated limits, andconclude that the limitsare insensitivetoanyunderestimationofthesystematicuncertainties. Limits on the product of crosssection andbranching fraction are set in the context of the benchmark model asa function of

m4. The natural width of the Z resonance is assumed to be

smaller than the mass resolutionof the detectorin all channels. The detector resolution in the μμμμ channel varies from 1.1% at m4=250GeV to 7.5% at m4=3TeV, and it has a constant

value of about 0.6% over this range in the eeee channel. In the limit calculation, we set the mass window to be six times the massresolutioncentredaround thesignalmasspoint considered. Acountingexperimentisperformedforthelimitcalculation.Fig. 3 shows the upper limits on the product of the cross section and branchingfraction,forthecombinationofallfivechannels,forthe massrangeconsideredinthebenchmarkmodelofRef.[29].Inthe framework ofthis model,we translate thesecross section upper limits into lower limits on the Z boson mass. Forthe combina-tion of thefive channels, the value obtainedfor thislower mass limitis2.5 TeV.Theblacksolid(dashed)lineindicatestheobserved (expected) 95% CL upper limits, the inner (outer) band indicates the ±1(2) standard deviationuncertainty inthe expectedlimits, and the blue dashed line shows the theoretical Z cross section for mϕ=50GeV.This theoretical cross section is calculated un-der thebenchmarkmodelassumptionthat thebranchingfraction

Fig. 3. The95%CLupperlimitonthe crosssection timesbranchingfractionas afunctionofm4forthecombinationofthefivechannels:fullmassrange(top) andexpandedviewofthelowmassregion(bottom).Theshaded green(yellow) bandindicates theone(two)sigmauncertaintyintheexpectedlimits.Theblue dashedlinerepresentsthetheoreticalpredictionsforthebenchmarkmodel[29]for mϕ=50GeV.(Forinterpretationofthereferencestocolourinthisfigurelegend, thereaderisreferredtothewebversionofthisarticle.)

Table 2

The95%CLlowerlimits(inTeV)onmZforthefiveseparatechannelsandfortheir

combination.Results arepresentedforthe benchmarkassumptionmϕ=50GeV, andforthefivedifferentvaluesoftheratiomϕ/mZ.

mϕ 50 GeV 0.05mZ 0.1mZ 0.2mZ 0.3mZ 0.4mZ μμμμ 1.7 1.6 1.7 1.7 1.7 1.7 μμμe 2.0 2.0 2.1 2.1 2.1 2.1 μμee 2.4 2.4 2.5 2.5 2.5 2.5 μeee 2.0 2.0 2.1 2.1 2.1 2.1 eeee 1.7 1.7 1.7 1.7 1.7 1.7 Combined 2.5 2.6 2.6 2.6 2.6 2.6

B(ϕ→ _{)=100%.In theregion abovethe 1–1.5 TeV,thebands} arenotvisiblesincebackgroundsarenegligiblehere.

Table 2 shows the exclusion limit on mZ for the five sepa-ratechannels andforthe combination. Results are presented for the benchmark assumptionmϕ=50GeV,and forthe five differ-entvalues of theratio mϕ /mZ assumed forthe generated signal samples, taking into account the event selection efficiencies de-scribed above.The predicted cross sectionsdecrease asthe ratio

mϕ /mZ increases.Thecontributionofthemergedleptonsignature

alsodecreases,resultinginanoverallefficiencyincrease.Therefore

the scenarios withmϕ/mZ=5, 10, 20,30 and 40% of mZ, give slightlyhigherlimitsthanthemϕ=50GeV scenario.

7. Summary

Results have been presented froma search for heavy narrow resonances decaying into four-lepton final states via intermedi-ate scalar particles ϕ, where the branching fraction of ϕ → 

(=e or μ) is setto 1. These resultsare basedon a sample of proton–proton collision data at √s=8TeV, corresponding to an integratedluminosityof19.7 fb−1.The four-leptoninvariant mass spectraareconsistentwiththestandardmodelpredictions.Masses ofZ’bosonshavebeenexcludedat95%confidencelevelfora spe-cific benchmark model withmϕ=50GeV, and for five different assumptions for the ratio mϕ/mZ (mϕ/mZ=5, 10, 20, 30 and 40%). Five decay channels (μμμμ, μμμe, μμee, μeee,eeee) are considered inthisanalysis. Combining all channels, alower limit on the Z mass of 2.5TeV is obtained forthe benchmark model, and2.6TeV foreachofthemodelsassumingafixedratiobetween

mϕ and mZ. Thisis thefirst result toconstrain a leptophobic Z

resonanceinthefour-leptonchannel.

Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrative staffsatCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentresand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythe computinginfrastructureessential to ouranalyses. Finally, we acknowledge the enduring support for the construc-tionandoperation oftheLHC andtheCMSdetectorprovidedby thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIEN-CIAS(Colombia);MSESandCSF(Croatia);RPF(Cyprus);SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Fin-land,MEC,andHIP(Finland);CEAandCNRS/IN2P3(France);BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hun-gary);DAEandDST(India);IPM(Iran);SFI(Ireland);INFN(Italy); MSIPandNRF(RepublicofKorea);LAS (Lithuania);MOEandUM (Malaysia); BUAP, CINVESTAV,CONACYT, LNS, SEP, andUASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland);FCT(Portugal);JINR(Dubna);MON, RosAtom,RAS,RFBR andRAEP(Russia);MESTD(Serbia);SEIDIandCPAN(Spain);Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, andNSTDA (Thailand); TUBITAK andTAEK (Turkey);NASU andSFFR(Ukraine);STFC(UnitedKingdom);DOEandNSF(USA).

Individuals have received support from the Marie-Curie pro-gramme and the European Research Council and EPLANET (Eu-ropean Union); the Leventis Foundation; the A.P. Sloan Founda-tion; the Alexander von Humboldt Foundation; the Belgian Fed-eral Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technolo-gie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) ofthe Czech Republic;the Council ofScience and Indus-trialResearch, India;the HOMING PLUSprogrammeofthe Foun-dation for Polish Science, cofinanced from European Union, Re-gional Development Fund, the Mobility Plus programme of the Ministry of Science and Higher Education, the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/ 02861, Sonata-bis 2012/07/E/ST2/01406; the Thalis and Aristeia

programmes cofinancedby EU-ESF andthe Greek NSRF; the Na-tional Priorities Research Program by Qatar National Research Fund; the Programa Clarín-COFUND del Principado de Asturias; theRachadapisekSompotFundforPostdoctoralFellowship, Chula-longkornUniversityandtheChulalongkornAcademicintoIts 2nd Century Project Advancement Project (Thailand); and the Welch Foundation,contractC-1845.

References

[1] A.Leike,Thephenomenologyofextraneutralgaugebosons,Phys.Rep.317 (1999) 143, http://dx.doi.org/10.1016/S0370-1573(98)00133-1, arXiv:hep-ph/ 9805494.

[2] J.L.Hewett,T.G.Rizzo,Low-energyphenomenologyofsuperstring-inspiredE6

models, Phys. Rep. 183(1989) 193,http://dx.doi.org/10.1016/0370-1573(89) 90071-9.

[3] K.R. Dienes,E.Dudas,T. Gherghetta,Extraspacetimedimensionsand unifi-cation,Phys. Lett.B436(1998)55,http://dx.doi.org/10.1016/S0370-2693(98) 00977-0,arXiv:hep-ph/9803466.

[4] T.Appelquist,H.-C.Cheng,B.A.Dobrescu,Boundsonuniversalextra dimen-sions,Phys.Rev.D64(2001)035002,http://dx.doi.org/10.1103/PhysRevD.64. 035002,arXiv:hep-ph/0012100.

[5] L. Randall, R. Sundrum, An alternative tocompactification, Phys. Rev. Lett. 83 (1999)4690, http://dx.doi.org/10.1103/PhysRevLett.83.4690, arXiv:hep-ph/ 9906064.

[6] L.Randall,R.Sundrum,Alargemasshierarchyfromasmallextradimension, Phys.Rev.Lett.83(1999)3370,http://dx.doi.org/10.1103/PhysRevLett.83.3370, arXiv:hep-ph/9905221.

[7] ATLASCollaboration,Searchfornewphenomenainthedijetmassdistribution usingpp collisiondataat√s=8TeV withtheATLASdetector,Phys.Rev.D91 (2015)052007,http://dx.doi.org/10.1103/PhysRevD.91.052007,arXiv:1407.1376. [8] ATLAS Collaboration, Searchfor newphenomenaindijetmass andangular distributions from pp collisions at √s=13 TeV with the ATLAS detector, Phys.Lett.B754(2016)302,http://dx.doi.org/10.1016/j.physletb.2016.01.032, arXiv:1512.01530.

[9] CMSCollaboration,Searchfornarrowresonancesusingthedijetmass spec-truminpp collisionsat√s=8 TeV,Phys.Rev.D87(2013)114015,http://dx. doi.org/10.1103/PhysRevD.87.114015,arXiv:1302.4794.

[10] CMSCollaboration,Searchfornarrowresonancesdecayingtodijetsinproton– protoncollisionsat√s=13 TeV,Phys.Rev.Lett.116(2016)071801,http://dx. doi.org/10.1103/PhysRevLett.116.071801,arXiv:1512.01224.

[11] ATLASCollaboration, Search for high-massdileptonresonancesin pp colli-sionsat√s=8 TeVwiththeATLASdetector,Phys.Rev.D90(2014)052005, http://dx.doi.org/10.1103/PhysRevD.90.052005,arXiv:1405.4123.

[12] ATLASCollaboration, Searchfor high-massnewphenomenainthe dilepton finale state using proton–proton collisions at √s=13 TeV with the AT-LASdetector,Phys.Lett.B761(2016)372,http://dx.doi.org/10.1016/j.physletb. 2016.08.055,arXiv:1607.03669.

[13] CMSCollaboration,Searchforphysicsbeyondthestandardmodelindilepton massspectrainproton–protoncollisionsat√s=8TeV,J.HighEnergyPhys.04 (2015)025,http://dx.doi.org/10.1007/JHEP04(2015)025,arXiv:1412.6302. [14] CMS Collaboration, Search for narrow resonances in dilepton mass

spec-tra inproton–protoncollisions at√s=13TeV andcombination with8 TeV data,Phys.Lett.B768(2017)57,https://doi.org/10.1016/j.physletb.2017.02.010, arXiv:1609.05391,2016.

[15] ATLASCollaboration,Searchforresonancesindiphotoneventsat√s=13TeV with the ATLAS detector,J. HighEnergy Phys.09 (2016)001, http://dx.doi. org/10.1007/JHEP09(2016)001,arXiv:1606.03833.

[16] CMSCollaboration,Searchforresonantproductionofhigh-massphotonpairs inproton–protoncollisionsat√s=8 and13 TeV,Phys.Rev.Lett.117(2016) 051802,http://dx.doi.org/10.1103/PhysRevLett.117.051802,arXiv:1606.04093. [17] CMSCollaboration,Searchforhigh-massdiphotonresonancesinproton–proton

collisionsat13 TeV andcombinationwith8 TeV search,Phys.Lett.B767(2017) 147,https://doi.org/10.1016/j.physletb.2017.01.027,arXiv:1609.02507,2016. [18] ATLASCollaboration,SearchforheavyresonancesdecayingtoaZbosonanda

photoninppcollisionsat√s=13 TeVwiththeATLASdetector,Phys.Lett. B764(2017) 11, http://dx.doi.org/10.1016/j.physletb.2016.11.005, arXiv:1607. 06363.

[19] ATLAS Collaboration, Searchfor Higgsboson pair production inthe hh→ bb¯τ τ, γ γW W∗, γ γbb¯, bbb¯ b channels¯ withtheATLAS detector,Phys.Rev.D 92(2015) 092004,http://dx.doi.org/10.1103/PhysRevD.92.092004, arXiv:1509. 04670.

[20] ATLASCollaboration,SearchforWZresonancesinthefullyleptonicchannel usingppcollisionsat√s=8 TeVwiththeATLASdetector,Phys.Lett.B737 (2014)223,http://dx.doi.org/10.1016/j.physletb.2014.08.039,arXiv:1406.4456. [21] CMS Collaboration, Search for high-mass Zγ resonances in e+e−γ and

μ+μ−γ finalstatesinproton–protoncollisionsat√s=8 and13 TeV,J.High

EnergyPhys.01(2017)076,http://dx.doi.org/10.1007/JHEP01(2017)076,arXiv: 1610.02960.

[22] CMS Collaboration, Search for high-mass Zγ resonances in proton–proton collisions at √s= 8 and 13 TeV using jet substructure techniques, Phys.Lett.B(2017),http://dx.doi.org/10.1016/j.physletb.2017.06.062,inpress, arXiv:1612.09516,2016.

[23] CMSCollaboration,SearchforheavyresonancesdecayingtotwoHiggsbosons infinalstatescontainingfourbquarks,Eur.Phys.J.C76(2016)371,http://dx. doi.org/10.1140/epjc/s10052-016-4206-6,arXiv:1602.08762.

[24] CMSCollaboration,SearchforamassiveresonancedecayingintoaHiggs bo-sonandaWorZbosoninhadronicfinalstatesinproton–protoncollisions at√s=8 TeV,J.HighEnergyPhys.02(2016)145,http://dx.doi.org/10.1007/ JHEP02(2016)145,arXiv:1506.01443.

[25] ATLAS Collaboration, Search for resonances decaying into top-quark pairs using fully hadronic decays in pp collisions with ATLAS at √s=7 TeV, J. HighEnergyPhys.01(2013)116,http://dx.doi.org/10.1007/JHEP01(2013)116, arXiv:1211.2202.

[26] ATLASCollaboration,Searchfortt resonancesusinglepton-plus-jetseventsin proton–protoncollisionsat√s=8 TeV withtheATLASdetector,J. HighEnergy Phys. 08 (2015)148, http://dx.doi.org/10.1007/JHEP08(2015)148, arXiv:1505. 0718.

[27] CMSCollaboration,Searchforanomaloustt productioninthehighly-boosted all-hadronicfinalstate,J.HighEnergyPhys.09(2012)029,http://dx.doi.org/ 10.1007/JHEP09(2012)029,arXiv:1204.2488.

[28] CMSCollaboration,Searchforresonantt¯t productioninproton–proton colli-sionsat√s=8TeV,Phys.Rev.D93(2016)012001,http://dx.doi.org/10.1103/ PhysRevD.93.012001,arXiv:1506.03062.

[29] V.Barger,H.-S.Lee,Four-leptonresonanceattheLargeHadronCollider,Phys. Rev.D85(2012)055030,http://dx.doi.org/10.1103/PhysRevD.85.055030,arXiv: 1111.0633.

[30] Y.Kuno,Y.Okada,Muondecayandphysicsbeyondthestandardmodel,Rev. Mod.Phys.73(2001)151,http://dx.doi.org/10.1103/RevModPhys.73.151,arXiv: hep-ph/9909265.

[31]A.deGouvea,P.Vogel,Leptonflavorandnumberconservationand physics beyondthestandardmodel,in:Fund.Sym.intheEraoftheLHC,in:Prog. Part.Nucl.Phys.,vol. 71,2013,p. 75,arXiv:1303.4097.

[32] D.K.Ghosh,P.Roy,S.Roy,FourleptonflavorviolatingsignalsattheLHC,J.High EnergyPhys.05(2012)067,http://dx.doi.org/10.1007/JHEP05(2012)067,arXiv: 1203.0187.

[33] CMSCollaboration,PerformanceofCMSmuonreconstructioninppcollision eventsat√s=7 TeV,J.Instrum.7(2012)P10002,http://dx.doi.org/10.1088/ 1748-0221/7/10/P10002,arXiv:1206.4071.

[34] CMS Collaboration, Performance of electron reconstruction and selection with the CMS detector in proton–proton collisions at √s=8 TeV, J. In-strum. 10(2015)P06005, http://dx.doi.org/10.1088/1748-0221/10/06/P06005, arXiv:1502.02701.

[35] CMSCollaboration,TheCMSexperimentattheCERNLHC,J.Instrum.3(2008) S08004,http://dx.doi.org/10.1088/1748-0221/3/08/S08004.

[36] A.Belyaev,N.Christensen,A.Pukhov,CalcHEP3.4forcolliderphysicswithin andbeyondthe StandardModel,Comput.Phys.Commun.184(2013) 1729, http://dx.doi.org/10.1016/j.cpc.2013.01.014,arXiv:1207.6082.

[37] T. Sjöstrand, S.Mrenna, P.Skands, PYTHIA6.4 physicsand manual, J.High EnergyPhys.05(2006)026,http://dx.doi.org/10.1088/1126-6708/2006/05/026, arXiv:hep-ph/0603175.

[38]T.Binoth, N. Kauerm,P.Mertsch, Gluon-inducedQCD corrections to pp→ ZZ→  ¯_¯_{,arXiv:0807.0024,2008.}

[39] S.Alioli,P.Nason,C.Oleari,E.Re,NLOvector-bosonproductionmatchedwith showerinPOWHEG,J.HighEnergyPhys.07(2008)060,http://dx.doi.org/10. 1088/1126-6708/2008/07/060,arXiv:0805.4802.

[40] J.Alwall,et al.,Madgraphv5:goingbeyond,J.HighEnergyPhys.06(2011) 128,http://dx.doi.org/10.1007/JHEP06(2011)128,arXiv:1106.0522.

[41] M. Czakon, P. Fiedler, A.Mitov, Total top-quark pair-production cross sec-tionat hadron collidersthrough o(α4

S),Phys. Rev.Lett.110(2013) 252004,

http://dx.doi.org/10.1103/PhysRevLett.110.252004,arXiv:1303.6254.

[42] J.M.Campbell,R.K.Ellis,C.Williams,VectorbosonpairproductionattheLHC, J.HighEnergyPhys.07(2011)018,http://dx.doi.org/10.1007/JHEP07(2011)018, arXiv:1105.0020.

[43] J.Pumplin,D.R.Stump,J.Huston,H.-L.Lai,P.Nadolsky,W.-K.Tung,New gen-erationofpartondistributions withuncertaintiesfromglobalQCD analysis, J.HighEnergyPhys.07(2002)012,http://dx.doi.org/10.1088/1126-6708/2002/ 07/012,arXiv:hep-ph/0201195.

[44] CMSCollaboration, Studyofthe underlyingeventatforwardrapidityinpp collisionsat √s=0.9, 2.76,and 7 TeV,J. HighEnergyPhys. 04(2013)072, http://dx.doi.org/10.1007/JHEP04(2013)072,arXiv:1302.2394.

[45] CMSCollaboration,Eventgeneratortunesobtainedfromunderlyingeventand multipartonscatteringmeasurements,Eur.Phys.J.C76(2016)155,http://dx. doi.org/10.1140/epjc/s10052-016-3988-x,arXiv:1512.00815.

[46] S.Agostinelli,etal., GEANT4,GEANT4–asimulationtoolkit,Nucl.Instrum. MethodsPhys.Res.,Sect.A,Accel.Spectrom.Detect.Assoc.Equip.506(2003) 250,http://dx.doi.org/10.1016/S0168-9002(03)01368-8.

[47] J.Allison,etal.,GEANT4developmentsandapplications,IEEETrans.Nucl.Sci. 53(2006)270,http://dx.doi.org/10.1109/TNS.2006.869826.

[48] ParticleDataGroup,K.A.Olive,etal.,Reviewofparticlephysics,Chin.Phys.C 38(2014)090001,http://dx.doi.org/10.1088/1674-1137/38/9/090001.

[49] CMSCollaboration,CMSLuminosityBasedonPixelClusterCounting– Sum-mer2013Update,CMSPhysicsAnalysisSummaryCMS-PAS-LUM-13-001,2013, http://cdsweb.cern.ch/record/1598864.

The CMS Collaboration

V. Khachatryan,A.M. Sirunyan, A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Erö,M. Flechl, M. Friedl, R. Frühwirth1, V.M. Ghete, C. Hartl, N. Hörmann, J. Hrubec,M. Jeitler1,A. König, I. Krätschmer, D. Liko, T. Matsushita,I. Mikulec, D. Rabady, N. Rad, B. Rahbaran,H. Rohringer, J. Schieck1,J. Strauss,

W. Treberer-Treberspurg,W. Waltenberger, C.-E. Wulz1

InstitutfürHochenergiephysik,Wien,Austria

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

NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

S. Alderweireldt, E.A. De Wolf,X. Janssen,J. Lauwers, M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen,N. Van Remortel, A. Van Spilbeeck

UniversiteitAntwerpen,Antwerpen,Belgium

S. Abu Zeid,F. Blekman, J. D’Hondt, N. Daci,I. De Bruyn, K. Deroover, N. Heracleous,S. Lowette, S. Moortgat, L. Moreels,A. Olbrechts,Q. Python, S. Tavernier, W. Van Doninck, P. Van Mulders, I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

H. Brun, C. Caillol, B. Clerbaux, G. De Lentdecker, H. Delannoy, G. Fasanella,L. Favart, R. Goldouzian, A. Grebenyuk,G. Karapostoli,T. Lenzi, A. Léonard,J. Luetic, T. Maerschalk,A. Marinov, A. Randle-conde, T. Seva,C. Vander Velde, P. Vanlaer,R. Yonamine, F. Zenoni, F. Zhang2

UniversitéLibredeBruxelles,Bruxelles,Belgium

A. Cimmino,T. Cornelis, D. Dobur,A. Fagot, G. Garcia,M. Gul, D. Poyraz, S. Salva, R. Schöfbeck, A. Sharma,M. Tytgat, W. Van Driessche, E. Yazgan,N. Zaganidis

GhentUniversity,Ghent,Belgium

H. Bakhshiansohi,C. Beluffi3,O. Bondu, S. Brochet,G. Bruno, A. Caudron, S. De Visscher, C. Delaere, M. Delcourt,B. Francois, A. Giammanco, A. Jafari,P. Jez, M. Komm,V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, C. Nuttens,K. Piotrzkowski, L. Quertenmont,M. Selvaggi, M. Vidal Marono, S. Wertz

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

N. Beliy

UniversitédeMons,Mons,Belgium

W.L. Aldá Júnior, F.L. Alves,G.A. Alves,L. Brito, C. Hensel,A. Moraes, M.E. Pol,P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato4, A. Custódio, E.M. Da Costa, G.G. Da Silveira5, D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson,

D. Matos Figueiredo, C. Mora Herrera,L. Mundim, H. Nogima,W.L. Prado Da Silva, A. Santoro, A. Sznajder,E.J. Tonelli Manganote4, A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahujaa, C.A. Bernardesb, S. Dograa,T.R. Fernandez Perez Tomeia, E.M. Gregoresb, P.G. Mercadanteb, C.S. Moona, S.F. Novaesa, Sandra S. Padulaa, D. Romero Abadb,J.C. Ruiz Vargas

a_{UniversidadeEstadualPaulista,SãoPaulo,Brazil} b_{UniversidadeFederaldoABC,SãoPaulo,Brazil}

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

M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen,M. Chen, Y. Chen7,T. Cheng, C.H. Jiang, D. Leggat, Z. Liu, F. Romeo,S.M. Shaheen, A. Spiezia, J. Tao, C. Wang,Z. Wang, H. Zhang, J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

Y. Ban, G. Chen, 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, C.F. González Hernández,J.D. Ruiz Alvarez, J.C. Sanabria

UniversidaddeLosAndes,Bogota,Colombia

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

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic, M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,D. Ferencek, K. Kadija,S. Micanovic, L. Sudic, T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

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

A.A. Abdelalim9,10, Y. Mohammed11, E. Salama12,13

B. Calpas,M. Kadastik, M. Murumaa, L. Perrini, 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, 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, S. Ghosh,A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, I. Kucher, E. Locci,M. Machet, J. Malcles,J. Rander, A. Rosowsky, M. Titov, A. Zghiche

IRFU,CEA,UniversitéParis-Saclay,Gif-sur-Yvette,France

A. Abdulsalam,I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro, E. Chapon,C. Charlot, O. Davignon,R. Granier de Cassagnac, M. Jo, S. Lisniak,P. Miné, M. Nguyen, 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, E. Conte14,X. Coubez, J.-C. Fontaine14, D. Gelé, U. Goerlach,A.-C. Le Bihan, K. Skovpen, P. Van Hove

InstitutPluridisciplinaireHubertCurien(IPHC),UniversitédeStrasbourg,CNRS-IN2P3,France

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,C. Bernet, G. Boudoul,E. Bouvier, C.A. Carrillo Montoya, R. Chierici,D. Contardo, B. Courbon,P. Depasse, H. El Mamouni,J. Fan, J. Fay, S. Gascon,M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde,I.B. Laktineh, M. Lethuillier,L. Mirabito, A.L. Pequegnot, S. Perries,A. Popov15,D. Sabes, V. Sordini,M. Vander Donckt, P. Verdier, S. Viret

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

T. Toriashvili16

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze8

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann,S. Beranek, L. Feld, A. Heister, M.K. Kiesel, K. Klein, M. Lipinski, A. Ostapchuk, M. Preuten, F. Raupach, S. Schael, C. Schomakers,J.F. Schulte,J. Schulz, T. Verlage,H. Weber, V. Zhukov15

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

A. Albert, M. Brodski,E. Dietz-Laursonn, D. Duchardt, M. Endres,M. Erdmann, S. Erdweg, T. Esch, R. Fischer,A. Güth, M. Hamer,T. Hebbeker, C. Heidemann, K. Hoepfner,S. Knutzen, M. Merschmeyer, A. Meyer,P. Millet, S. Mukherjee,M. Olschewski, K. Padeken, T. Pook,M. Radziej, H. Reithler, M. Rieger, F. Scheuch,L. Sonnenschein, D. Teyssier,S. Thüer

V. Cherepanov, G. Flügge, W. Haj Ahmad, F. Hoehle, B. Kargoll, T. Kress, A. Künsken,J. Lingemann, T. Müller,A. Nehrkorn, A. Nowack,I.M. Nugent,C. Pistone, O. Pooth,A. Stahl17

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,C. Asawatangtrakuldee, K. Beernaert, O. Behnke,U. Behrens, A.A. Bin Anuar, K. Borras18,A. Campbell, P. Connor, C. Contreras-Campana, F. Costanza, C. Diez Pardos,G. Dolinska, G. Eckerlin, D. Eckstein, T. Eichhorn, E. Eren, E. Gallo19,J. Garay Garcia, A. Geiser, A. Gizhko,

J.M. Grados Luyando, P. Gunnellini, A. Harb, J. Hauk, M. Hempel20,H. Jung, A. Kalogeropoulos, O. Karacheban20,M. Kasemann, J. Keaveney, C. Kleinwort,I. Korol, D. Krücker,W. Lange, A. Lelek,

J. Leonard, K. Lipka,A. Lobanov, W. Lohmann20,R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, E. Ntomari,D. Pitzl, R. Placakyte, A. Raspereza,B. Roland, M.Ö. Sahin,P. Saxena, T. Schoerner-Sadenius,C. Seitz, S. Spannagel, N. Stefaniuk, G.P. Van Onsem,R. Walsh, C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

V. Blobel, M. Centis Vignali, A.R. Draeger,T. Dreyer, E. Garutti, D. Gonzalez, J. Haller, M. Hoffmann, A. Junkes, R. Klanner, R. Kogler,N. Kovalchuk, T. Lapsien, T. Lenz, I. Marchesini,D. Marconi, M. Meyer, M. Niedziela, D. Nowatschin, F. Pantaleo17,T. Peiffer, A. Perieanu, J. Poehlsen, C. Sander,C. Scharf, P. Schleper, A. Schmidt, S. Schumann,J. Schwandt, H. Stadie,G. Steinbrück, F.M. Stober,M. Stöver, H. Tholen, D. Troendle,E. Usai, L. Vanelderen, A. Vanhoefer, B. Vormwald

UniversityofHamburg,Hamburg,Germany

C. Barth,C. Baus, J. Berger,E. Butz, T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm,S. Fink, R. Friese, M. Giffels,A. Gilbert, P. Goldenzweig,D. Haitz, F. Hartmann17,S.M. Heindl, U. Husemann,I. Katkov15, P. Lobelle Pardo, B. Maier, H. Mildner, M.U. Mozer, Th. Müller, M. Plagge, G. Quast, K. Rabbertz, S. Röcker, F. Roscher,M. Schröder, I. Shvetsov,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, I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

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

NationalandKapodistrianUniversityofAthens,Athens,Greece

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

UniversityofIoánnina,Ioánnina,Greece

N. Filipovic

MTA-ELTELendületCMSParticleandNuclearPhysicsGroup,EötvösLorándUniversity,Budapest,Hungary

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,A. Makovec, J. Molnar,Z. Szillasi

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

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

InstituteofPhysics,UniversityofDebrecen,Hungary

S. Bahinipati, S. Choudhury24,P. Mal, K. Mandal, A. Nayak25, D.K. Sahoo,N. Sahoo, S.K. Swain

S. Bansal,S.B. Beri, V. Bhatnagar, R. Chawla, U. Bhawandeep, A.K. Kalsi,A. Kaur, M. Kaur, R. Kumar, P. Kumari,A. Mehta, M. Mittal, J.B. Singh, G. Walia

PanjabUniversity,Chandigarh,India

Ashok Kumar,A. Bhardwaj, B.C. Choudhary, R.B. Garg,S. Keshri, S. Malhotra,M. Naimuddin, N. Nishu, K. Ranjan,R. Sharma, V. Sharma

UniversityofDelhi,Delhi,India

R. Bhattacharya,S. Bhattacharya, K. Chatterjee, S. Dey,S. Dutt, S. Dutta, S. Ghosh, N. Majumdar, A. Modak, K. Mondal,S. Mukhopadhyay, S. Nandan,A. Purohit, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar,M. Sharan, S. Thakur

SahaInstituteofNuclearPhysics,Kolkata,India

P.K. Behera

IndianInstituteofTechnologyMadras,Madras,India

R. Chudasama,D. Dutta, V. Jha, V. Kumar, A.K. Mohanty17, P.K. Netrakanti,L.M. Pant, P. Shukla,A. Topkar

BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz,S. Dugad, G. Kole, B. Mahakud, S. Mitra, G.B. Mohanty, B. Parida,N. Sur, B. Sutar

TataInstituteofFundamentalResearch-A,Mumbai,India

S. Banerjee, S. Bhowmik26,R.K. Dewanjee, S. Ganguly,M. Guchait, Sa. Jain, S. Kumar, M. Maity26, G. Majumder,K. Mazumdar, T. Sarkar26, N. Wickramage27

TataInstituteofFundamentalResearch-B,Mumbai,India

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

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

H. Behnamian,S. Chenarani28, E. Eskandari Tadavani,S.M. Etesami28,A. Fahim29,M. Khakzad, M. Mohammadi Najafabadi,M. Naseri, S. Paktinat Mehdiabadi30, F. Rezaei Hosseinabadi, B. Safarzadeh31, 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,17,R. Vendittia,b, P. Verwilligena

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

G. Abbiendia,C. Battilana, 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,17

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

S. Albergoa,b,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,17

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

L. Benussi, S. Bianco, F. Fabbri,D. Piccolo, F. Primavera17

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. Brianza17,M.E. Dinardoa,b,S. Fiorendia,b,S. Gennaia, A. Ghezzia,b, P. Govonia,b, M. Malberti,

S. Malvezzia, R.A. Manzonia,b,17, B. Marzocchia,b,D. Menascea,L. Moronia,M. Paganonia,b,D. Pedrinia, S. Pigazzini,S. Ragazzia,b,T. Tabarelli de Fatisa,b

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

S. Buontempoa, N. Cavalloa,c, G. De Nardo, S. Di Guidaa,d,17, M. Espositoa,b, F. Fabozzia,c, A.O.M. Iorioa,b, G. Lanzaa,L. Listaa, S. Meolaa,d,17,P. Paoluccia,17, 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,17, N. Bacchettaa, L. Benatoa,b,D. Biselloa,b, A. Bolettia,b,R. Carlina,b,

A. Carvalho Antunes De Oliveiraa,b, P. Checchiaa,M. Dall’Ossoa,b,P. De Castro Manzanoa,T. Dorigoa, U. Dossellia,F. Gasparinia,b,U. Gasparinia,b,A. Gozzelinoa,S. Lacapraraa, M. Margonia,b,

A.T. Meneguzzoa,b,J. Pazzinia,b,17, N. Pozzobona,b,P. Ronchesea,b, F. Simonettoa,b,E. Torassaa, M. Zanetti,P. Zottoa,b,A. Zucchettaa,b,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,32,P. Azzurria,17, G. Bagliesia, J. Bernardinia, T. Boccalia, R. Castaldia,M.A. Cioccia,32, R. Dell’Orsoa,S. Donatoa,c,G. Fedi, A. Giassia, M.T. Grippoa,32, F. Ligabuea,c,T. Lomtadzea,L. Martinia,b, A. Messineoa,b_{, F. Palla}a_{,A. Rizzi}a,b_{, A. Savoy-Navarro}a,33_{,P. Spagnolo}a_{,R. Tenchini}a_{,G. Tonelli}a,b_,

A. Venturia, P.G. Verdinia a_{INFNSezionediPisa,Pisa,Italy}

b_{UniversitàdiPisa,Pisa,Italy}

L. Baronea,b, F. Cavallaria,M. Cipriania,b, G. D’imperioa,b,17,D. Del Rea,b,17,M. Diemoza, S. Gellia,b, 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,17,S. Argiroa,b,M. Arneodoa,c,N. Bartosika,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,G. Mazzaa,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, F. Rotondoa, M. Ruspaa,c,R. Sacchia,b,V. Solaa, A. Solanoa,b, A. Staianoa, P. Traczyka,b

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

c_{UniversitàdelPiemonteOrientale,Novara,Italy}

S. Belfortea,M. Casarsaa, F. Cossuttia,G. Della Riccaa,b, C. La Licataa,b, A. Schizzia,b, A. Zanettia a_{INFNSezionediTrieste,Trieste,Italy}

b_{UniversitàdiTrieste,Trieste,Italy}

D.H. Kim,G.N. Kim, M.S. Kim, S. Lee, S.W. Lee, Y.D. Oh,S. Sekmen, D.C. Son,Y.C. Yang

KyungpookNationalUniversity,Daegu,RepublicofKorea

A. Lee

ChonbukNationalUniversity,Jeonju,RepublicofKorea

H. Kim

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

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

HanyangUniversity,Seoul,RepublicofKorea

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

KoreaUniversity,Seoul,RepublicofKorea

J. Almond,J. Kim, H. Lee,S.B. Oh, B.C. Radburn-Smith, S.h. Seo, U.K. Yang,H.D. Yoo, G.B. Yu

SeoulNationalUniversity,Seoul,RepublicofKorea

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

UniversityofSeoul,Seoul,RepublicofKorea

Y. Choi,J. Goh, C. Hwang, 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

H. Castilla-Valdez, E. De La Cruz-Burelo,I. Heredia-De La Cruz36,A. Hernandez-Almada, R. Lopez-Fernandez, R. Magaña Villalba, J. Mejia Guisao,A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia

UniversidadIberoamericana,MexicoCity,Mexico

S. Carpinteyro, I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada

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, A. Saddique,M.A. Shah, 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. Zalewski

NationalCentreforNuclearResearch,Swierk,Poland

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, J. Rodrigues Antunes, J. Seixas,O. Toldaiev, D. Vadruccio,J. Varela, P. Vischia

LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal

I. Belotelov,P. Bunin, I. Golutvin, I. Gorbunov, V. Karjavin, G. Kozlov, A. Lanev,A. Malakhov,

V. Matveev38,39, P. Moisenz, V. Palichik,V. Perelygin, M. Savina, S. Shmatov, S. Shulha,N. Skatchkov, V. Smirnov, N. Voytishin, A. Zarubin

JointInstituteforNuclearResearch,Dubna,Russia

L. Chtchipounov,V. Golovtsov, Y. Ivanov, V. Kim40, E. Kuznetsova41,V. Murzin, V. Oreshkin, V. Sulimov, 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,M. Toms, E. Vlasov, A. Zhokin

A. Bylinkin39

MoscowInstituteofPhysicsandTechnology,Moscow,Russia

R. Chistov42, M. Danilov42,V. Rusinov

NationalResearchNuclearUniversity, ‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

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

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,V. Bunichev, M. Dubinin43, L. Dudko, V. Klyukhin, O. Kodolova, I. Lokhtin,I. Miagkov, S. Obraztsov,M. Perfilov, S. Petrushanko,V. Savrin, A. Snigirev

SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,Russia

V. Blinov44, Y. Skovpen44

NovosibirskStateUniversity(NSU),Novosibirsk,Russia

I. Azhgirey,I. Bayshev,S. Bitioukov, D. Elumakhov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol,S. Troshin, N. Tyurin,A. Uzunian, A. Volkov

StateResearchCenterofRussianFederation,InstituteforHighEnergyPhysics,Protvino,Russia

P. Adzic45,P. Cirkovic, D. Devetak,M. Dordevic, J. Milosevic,V. Rekovic

UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia

J. Alcaraz Maestre,M. Barrio Luna, 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, I. Gonzalez Caballero, J.R. González Fernández,E. Palencia Cortezon, S. Sanchez Cruz,I. Suárez Andrés, J.M. Vizan Garcia

UniversidaddeOviedo,Oviedo,Spain

I.J. Cabrillo, A. Calderon, J.R. Castiñeiras De Saa, E. Curras, M. Fernandez,J. Garcia-Ferrero,G. Gomez, A. Lopez Virto,J. Marco, C. Martinez Rivero,F. Matorras, J. Piedra Gomez, T. Rodrigo, 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, P. Bloch,A. Bocci, A. Bonato,C. Botta, T. Camporesi, R. Castello, M. Cepeda, G. Cerminara, M. D’Alfonso, D. d’Enterria, A. Dabrowski,V. Daponte, A. David, M. De Gruttola, A. De Roeck, E. Di Marco46, M. Dobson, B. Dorney, T. du Pree,D. Duggan, M. Dünser,N. Dupont, A. Elliott-Peisert,S. Fartoukh, G. Franzoni, J. Fulcher, W. Funk, D. Gigi,K. Gill, M. Girone, F. Glege, D. Gulhan, S. Gundacker, M. Guthoff,J. Hammer, P. Harris, J. Hegeman,V. Innocente, P. Janot, J. Kieseler, H. Kirschenmann,V. Knünz, A. Kornmayer17,

M.J. Kortelainen, K. Kousouris,M. Krammer1,C. Lange, P. Lecoq, C. Lourenço,M.T. Lucchini,L. Malgeri, M. Mannelli,A. Martelli, F. Meijers, J.A. Merlin, S. Mersi,E. Meschi, F. Moortgat, S. Morovic, M. Mulders, H. Neugebauer,S. Orfanelli, L. Orsini,L. Pape, E. Perez, M. Peruzzi,A. Petrilli, G. Petrucciani,A. Pfeiffer, M. Pierini,A. Racz,T. Reis, G. Rolandi47,M. Rovere, M. Ruan,H. Sakulin, J.B. Sauvan, C. Schäfer,

C. Schwick,M. Seidel, A. Sharma,P. Silva, P. Sphicas48, J. Steggemann,M. Stoye, Y. Takahashi, M. Tosi, D. Treille, A. Triossi,A. Tsirou, V. Veckalns49,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, 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. Starodumov50,V.R. Tavolaro,K. Theofilatos, R. Wallny

InstituteforParticlePhysics,ETHZurich,Zurich,Switzerland

T.K. Aarrestad, C. Amsler51, L. Caminada,M.F. Canelli, A. De Cosa, C. Galloni,A. Hinzmann, T. Hreus, B. Kilminster, J. Ngadiuba,D. Pinna,G. Rauco, P. Robmann, D. Salerno, Y. Yang

UniversitätZürich,Zurich,Switzerland

V. Candelise,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, W.-S. Hou, Y. Hsiung, Y.F. Liu,R.-S. Lu, M. Miñano Moya, E. Paganis, A. Psallidas,J.f. Tsai, Y.M. Tzeng

NationalTaiwanUniversity(NTU),Taipei,Taiwan

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

ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

A. Adiguzel, S. Cerci52,S. Damarseckin, Z.S. Demiroglu, C. Dozen,I. Dumanoglu, S. Girgis, G. Gokbulut, Y. Guler, I. Hos,E.E. Kangal53,O. Kara, A. Kayis Topaksu, U. Kiminsu,M. Oglakci, G. Onengut54,

K. Ozdemir55, D. Sunar Cerci52, H. Topakli56,S. Turkcapar, I.S. Zorbakir,C. Zorbilmez

CukurovaUniversity, PhysicsDepartment,ScienceandArtFaculty,Turkey

B. Bilin, S. Bilmis, B. Isildak57, G. Karapinar58, M. Yalvac, M. Zeyrek

MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E. Gülmez,M. Kaya59,O. Kaya60, E.A. Yetkin61, T. Yetkin62

BogaziciUniversity,Istanbul,Turkey

A. Cakir,K. Cankocak, S. Sen63

IstanbulTechnicalUniversity,Istanbul,Turkey

B. Grynyov

InstituteforScintillationMaterialsofNationalAcademyofScienceofUkraine,Kharkov,Ukraine

L. Levchuk,P. Sorokin

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, D.M. Newbold64, S. Paramesvaran, A. Poll, T. Sakuma,S. Seif El Nasr-storey, D. Smith,V.J. Smith

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell,A. Belyaev65,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

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, R. Di Maria, P. Dunne, A. Elwood, D. Futyan,Y. Haddad, G. Hall,G. Iles, T. James, R. Lane, C. Laner, R. Lucas64,L. Lyons, A.-M. Magnan,S. Malik, L. Mastrolorenzo, J. Nash, A. Nikitenko50,J. Pela, B. Penning, M. Pesaresi, D.M. Raymond, A. Richards,A. Rose,C. Seez, S. Summers,A. Tapper, K. Uchida, M. Vazquez Acosta66, T. Virdee17, J. Wright,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,C. West

TheUniversityofAlabama,Tuscaloosa,USA

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

BostonUniversity,Boston,USA

G. Benelli, E. Berry,D. Cutts, A. Garabedian,J. Hakala, U. Heintz, J.M. Hogan,O. Jesus, E. Laird, G. Landsberg, Z. Mao,M. Narain, S. Piperov,S. Sagir, E. Spencer, R. Syarif

BrownUniversity,Providence,USA

R. Breedon,G. Breto, D. Burns,M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher,C. Flores, G. Funk, M. Gardner,W. Ko, R. Lander, C. Mclean,

M. Mulhearn,D. Pellett,J. Pilot, S. Shalhout,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, S.M.A. Ghiasi Shirazi,G. Hanson,J. Heilman, P. Jandir, E. Kennedy, F. Lacroix,O.R. Long, M. Olmedo Negrete, M.I. Paneva, A. Shrinivas,W. Si, H. Wei,S. Wimpenny,

B.R. Yates

UniversityofCalifornia,Riverside,Riverside,USA

J.G. Branson, G.B. Cerati,S. Cittolin, M. Derdzinski, R. Gerosa, A. Holzner, D. Klein, V. Krutelyov, J. Letts, D. Olivito,S. Padhi, M. Pieri, M. Sani, V. Sharma, M. Tadel,A. Vartak, S. Wasserbaech67, C. Welke, J. Wood, F. Würthwein,A. Yagil,G. Zevi Della Porta