Search for excited quarks of light and heavy flavor in gamma plus jet final states in proton-proton collisions at √s=13 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

excited

quarks

of

light

and

heavy

flavor

in

γ

+

jet final

states

in

proton–proton

collisions

at

√

s

=

13 TeV

.TheCMS Collaboration

CERN,Switzerland

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

Articlehistory:

Received13November2017

Receivedinrevisedform22February2018 Accepted3April2018

Availableonline9April2018 Editor:M.Doser

Keywords:

CMS Physics Excitedquarks

Asearchispresentedforexcitedquarksoflightandheavyflavorthatdecaytoγ+jet finalstates.The analysis isbasedondata correspondingtoanintegratedluminosity of35.9 fb−1 collectedbytheCMS experimentinproton–protoncollisionsat√s=13TeV attheLHC.Asignalwouldappearasaresonant contributiontotheinvariantmassspectrumoftheγ+jet system,abovethebackgroundexpectedfrom standard modelprocesses.Noresonantexcessisfound,andupperlimitsaresetontheproductofthe excited quark cross sectionand its branching fraction as a functionofits mass. Theseare the most stringentlimits todateintheγ+jet finalstate, andexcludeexcitedlightquarkswithmassesbelow 5.5 TeV andexcitedbquarkswithmassesbelow1.8 TeV,assumingstandardmodellikecouplingstrengths. ©2018TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Highenergyproton–protoncollisionsresultinginaphotonand a jet with large transverse momenta (pT) provide a powerful

meansof searchingfornewphysics.Forexample,models involv-ing compositeness [1–3] predict excited statesofquarksthat can be identified by searching for events that contain a photon and ajet fromtheir decays.Wepresenta search forexcitedstates of light(u,d)andheavy(b)quarksusingthisdecaysignature.

We assumethat the couplingbetweenthe excited quark (q_), theordinaryquarks,andgaugebosonsproceedsthrougha gauge-invariant magnetic-moment operator, described by the effective Lagrangian [4]: Lint= 1 2q  Rσμν  gsfs λa 2 G a μν +g fτ 2·Wμν + g _fY 2Bμν  qL+h.c., (1) whereq

R is theright-handed excited quark field; σμν thePauli

spin matrix; qL theleft-handedquark field; Gaμν , W μν ,and Bμν

are the field tensors of the SU(3), SU(2), and U(1) gauge fields respectively; λa, τ,and Y are the corresponding gauge structure constants,andgs,g,andgarethegaugecouplings.The compos-iteness scale  isthe energyscale typical for theseinteractions. Thequantities fs, f ,and fareunknowndimensionlessconstants

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

that representthestrengths oftheexcitedquark couplingstothe standardmodel(SM)partners.Theirvaluesaredeterminedbythe compositeness dynamics,andare usuallyassumedto be oforder unity.

In pp collisions, excited quarks are expected to be produced predominantly through quark–gluon fusion (qg), and then decay into a quark and a gauge boson (g,W,Z, γ). Searcheshave been performed in different channels [5–12], butno evidence for the existenceofexcitedquarkshasyetbeenfound.Thisanalysislooks for evidence of qg→q→qγ (where q represents u or d)and bg→b_{→bγ productionby searchingforresonancesin γ+jet} finalstates.Thesignalmodelincludesexcitedquarkswithspin-1₂, and assumes a compositeness scale that equals the mass of the resonance (mRes).An assumption isalso madethat fs, f , and f haveidenticalvalues [3,4] andhenceforththesewillbereferredto collectivelyas f .The datacorrespondtoan integratedluminosity of 35.9 fb−1 collected by the CMSexperiment in pp collisions at √

s=13TeV attheCERNLHC,in2016.

A final state with a photon and a jet is produced in the SM mainly through qg→qγ, qq→gγ, gg→gγ, multijet, and W/Z+γ processes. Among these, the main irreducible back-grounds are quark–gluon Compton scattering (qg→qγ) and quark–antiquark annihilation (qq→gγ). Although the probabil-ityforajettobereconstructedasaphotonis≈10−4to10−3,the crosssectionformultijetproductionistwotothreeordersof mag-nitudelargerthanthatfortheirreduciblebackgrounds,depending onthe pT ofthejet [13],makingjetmisidentificationthe

second-largestsourceofbackground.ElectroweakproductionofW/Z+γ, wheretheWorZbosondecaystoapairofquarkjets,contributes

https://doi.org/10.1016/j.physletb.2018.04.007

0370-2693/©2018TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

averysmallfractionofthebackgroundduetoitssmallproduction crosssection.

ThisLetterprovides abriefdescriptionofthe CMSdetectorin Section 2.The main strategy used in selecting the eventsis dis-cussed in Section 3. Section 4 contains information about signal andbackgroundmodels, while Section 5 lists thesystematic un-certaintiesestimatedinthisanalysis.The resultsofthestudyare presentedinSection6andsummarizedinSection7.

2. TheCMSdetector

The central feature of the CMS detector is a superconduct-ing solenoidof 6 m internal diameter,providing a magnetic field of 3.8 T.Withinthesolenoid volumeare a siliconpixel andstrip tracker,aleadtungstatecrystalelectromagneticcalorimeter(ECAL), andabrassandscintillatorhadroncalorimeter(HCAL),each com-posedofa barrelandtwo endcapsections.The very forward re-gionsofthedetectornearthebeamlineiscoveredbytheforward calorimeters.Muonsaremeasured ingas-ionizationdetectors em-beddedin the steelflux-return yokeoutside thesolenoid. In the barrel section of the ECAL, an energy resolution of about 1% is achieved forunconverted or late-converting photonsin the tens of GeV energyrange.Theremainingbarrelphotonshavea resolu-tionofabout1.3%uptopseudorapidity|η|=1 risingtoabout2.5% at|η|=1.4 [13],where ηisdefinedas−ln[tan(θ/2)],θbeingthe polarangleofthe cylindricalcoordinates ofthe CMSdetector.In theendcaps,theresolutionofunconvertedorlate-converting pho-tons is about 2.5%, while the remaining endcap photons have a resolutionbetween3–4%. When combininginformation fromthe entiredetector, the jet energy resolution is typically around 15% at10 GeV, 8% at 100 GeV, and4% at 1 TeV. A more detailed de-scription of the CMS detector, together with a definition of the coordinatesystemusedandthe relevantkinematicvariables, can befoundin [14].

The CMS experiment selects physics events using a two-tier triggersystem,ahardware-basedlevel-1(L1)andasoftware-based high-leveltrigger(HLT).TheL1triggerselectseventsofinterest us-inginformationfromthecalorimetersandthemuonsystemonly, andreducesthereadoutratefromthebunchcrossingfrequencyof 40 MHz tobelow100 kHz. The HLTsystemfurther decreasesthis rateto an average ofa few 100 Hz to a maximumof 1 kHz.The eventsselectedbytheHLTarethenreconstructedofflineandused foranalysis.

3. Eventselection

Events are analyzed using a particle-flow (PF) algorithm [15], whichreconstructsandidentifies eachindividual particlewithan optimizedcombinationof informationfromthe various elements of the CMS detector. The energy of photons is directly obtained from the ECAL measurement, corrected for zero-suppression ef-fects [13].Theenergyofelectrons isdeterminedfroma combina-tionoftheelectron momentumattheprimary interactionvertex as determined by the tracker, the energy of the corresponding ECALcluster, andthe energy sum ofall bremsstrahlungphotons spatiallycompatiblewithoriginatingfromthe electrontrack.The energy of muons is obtained from the curvature of the corre-spondingtrack.Theenergyofchargedhadronsisdeterminedfrom a combination of their momentum measured in the tracker and thematchingECALandHCALenergydeposits,correctedfor zero-suppressioneffectsandfortheresponsefunctionofthe calorime-terstohadronicshowers.Finally,theenergyofneutralhadronsis obtainedfromthecorrespondingcorrectedECALandHCALenergy. The jets in each event are formed mainly from photons, charged,andneutralhadronsusingtheinfrared- andcollinear-safe

anti-kT algorithm [16], withdistance parameter R=0.4 where

R=(η)2+ (φ)2,ηandφ beingthepseudorapidityand azimuthalangle(inradians)differencebetweenthejetaxisandits constituents.Jetmomentaandenergiesarecorrectedtoestablisha uniformcalorimetricresponsein ηandanabsoluteresponsein pT

attheparticlelevelusingcalibrationconstants [17] obtainedfrom simulation,testbeamresults,andppcollisiondataat√s=13TeV. The data sample used in this analysis consistsof events that areselectedbyaphotontriggerhavinga pγ_T thresholdof165 GeV andan additionalconditionontheratioofthephotonenergy de-positedin theHCALto that inthe ECAL(H/E), whichis required tobelessthan10%.Theefficiencyofthetriggerusedinthestudy hasbeen evaluated separately using samplescollected with pho-ton,muon,orjet triggerstoaccountforpossiblebiasesintrigger selection. The trigger efficiencies measured in thesesamples are greaterthan95%forpγ_T >200 GeV,asmeasuredoffline.

Intheoffline selection,each eventisrequiredtohaveatleast one reconstructed primary vertex with at least four associated tracks, and lie within 24 cm along the z direction and within 2 cm inthetransverseplane,fromthenominalcollisionpoint.The reconstructed vertex with the largest value of summed physics-objectp2

Tistakenastheprimaryppinteractionvertex.Thephysics

objectsare thejets, clusteredusingthejet findingalgorithm [16, 18] withthetracksassignedtothevertexasinputs,andthe asso-ciatedmissingtransversemomentum,takenasthenegativevector sumofthe pT ofthosejets.

Thephotonidentification [13] isbasedonrequirementsonH/E and shower profile of the photon. The photon is isolated from identifiedelectronsinthedetectorbyrequiringtheabsenceofhits intheinnertrackerlayersnearthephotondirection.Thephotonis alsorequiredtobewell isolatedfromotherphotonsandhadrons withinaconeofR=0.3 arounditsaxis.Thephotonmusthave

pγ_T >200 GeV andlieinthecentralbarrelregion(|ηγ_|<1.4442).

Among the photonspassing theabove criteriain each event, the onewiththehighestpT isselectedtoreconstructthemassofthe

photon+jetsystemintheevent.Theisolation quantitiesare cor-rectedforeffectsfromoverlapping ppinteractions (pileup)inthe sameor adjacentbunch crossings, bysubtracting the energy cal-culated fromthemeanenergydensityintheevent, ascomputed usingtheFastJet package [18].Thephoton identificationand iso-lation criteria used in this analysislead to a signal efficiency of ∼80%withanestimatedbackgroundrejectionof∼90%.

In order to be combined witha photon to form a resonance candidate,theselectedjet mustbeseparatedfromthechosen pho-ton candidateby R>0.5 and satisfy thetight jet identification criteria[19]. The jet identificationcriteriacomprise requirements on thenumberof constituents,andon thefractionof jet energy carriedby eachconstituenttype. Thejet isrequiredto bewithin the region |ηjet_{|<2.4 and must have a p}jet

T >170 GeV. The

an-gularseparationbetweentheselectedphotonandjetisrestricted by applyinga requirementofη(γ,jet)<1.5. Thisselection re-moves a large fraction of the multijet background coming from non-isolated π0_{s, without rejecting signal events, and thus}

en-hancesthesignal-over-backgroundratio.Ifmorethanonejet can-didateispresentintheevent, thejet withthehighest pT isused

inthe analysis. The selectedeventsform the“inclusivecategory” forthesearchoflightexcitedquarks.

Jets originating from b quarks are identified using the com-bined secondary vertex v2 algorithm (CSVv2) [20,21]. The algo-rithm combinesthe informationfromthe primary vertex,impact parameters, andsecondary vertices within the jet usinga neural networkdiscriminator.Thelooseworkingpointusedinthe analy-sishas∼81%bjetselectionefficiency,∼10%misidentificationrate forlight-quarkandgluonjets,and∼40%misidentificationratefor c quark jets [20]. Depending onthe outcome of theCSVv2

algo-Fig. 1. Theproductofacceptanceandefficiencyforq_andb_{signalsasafunction}

ofgeneratedmqormb mass,calculatedusingMCsimulation.

rithm, a jet is taggedeither asa b jet or a non b jet candidate. Accordingtothistagging,fortheb analysis,theeventsare clas-sifiedinto “1btag” and“0btag” categories, corresponding tothe selectionswithbjetsandwithoutbjetsrespectively.Sincetheb acceptancefalls offslightly for1b tag category athigher masses (Fig.1),thesensitivityofthesearchisimprovedby includingthe resultsfrom0btagcategoryintheb_{limitcomputation.}

Theaboveselectioncriteriaareoptimizedforthebestexpected 95%confidence level(CL)limitsonthe crosssection versusmass ofq_andb_.

The efficiencies forassigning events to the1b tag and0btag categories,determinedfromtheMonteCarlo(MC)simulation,are correctedusing btagscale factors(SFs), totake into accountthe observeddifferencesbetweenthebtaggingefficiencyoftheCSVv2 taggerappliedtodataandtoMC simulation.TheSFsare defined as data/MC, where data and MC correspond to the b tagging

efficiencies of the CSVv2 algorithms in data and MC simulation, respectively. TheseSFshavebeen measured usingthetechniques describedin [20].

Theinvariantmassoftheselected γ+jet (γ +b jet)systemis requiredtobemγ+jet>700GeV,toavoidtheturn-onregiondue

to the requirements imposed on the kinematic properties ofthe triggerobjects.Fig.1showsthetotalselection andreconstruction efficiencytimesacceptance forq→qγ and b→bγ processes. Theacceptancetimesefficiencyforthe1btag categorydecreases withincreasingmassowingtothedecreaseintheefficiencyofthe trackreconstructionandtheresolutionofthereconstructed track parameterswithincreasing pTofthejet.

4. Modeling signalandbackground

Thesignalsamplesforq_andb_{aresimulatedatleadingorder} (LO) withthe pythia 8.212 eventgenerator [22] for f =1.0, 0.5 and0.1atdifferentresonancemassesintherangefrom1to7 TeV atintervalsof1 TeV andfrom1to5 TeV atintervalsof0.5 TeV, re-spectively.ThegeneratedeventsareprocessedthroughafullCMS detectorsimulationbasedon Geant4 [23].Thesimulationusesthe CUETP8M1 underlying event tune [24,25], a renormalization and factorizationscalecorresponding to μ =pT forthehard-scattered

partons,andNNPDF2.3LOpartondistributionfunctions(PDFs) [26].

Fig. 2. The γ+jet invariant massdistributionindata (blackpoints)for the in-clusive categoryusedforthe q_{analysis, afterfinalselection.Theresult ofthe}

fittothedatausingtheparametrizationdefinedinEq. (2) isshownbytheblue dashedcurvewithassociatedbandsindicatingtheuncertainty.Thebin-by-binpull, (Data-Fit)/(stat.unc.),wherethedenominatorreferstothestatisticaluncertaintyin data,isalsopresented.Thegreenandyellowbandscorrespond to1and2standard deviations,respectivelyfromthemeanvalue.Simulationsofexcitedquarksignals representingtheexpectedexcessofsignaleventsoverthebackgroundareshown forthemassvaluesof1.0and5.0 TeV for f=1.0,and2.0 TeV for f=0.5.(For in-terpretationofthecolorsinthefigure(s),thereaderisreferredtothewebversion ofthisarticle.)

Thenaturalwidthoftheresonance,atpartonlevel,canbe approx-imatedas∼0.03 f2_m

Res [3].Theproductioncrosssectionisalso

proportional to f2.The signalsfor intermediate mass points are interpolatedatintervalsof50 GeV.

The MadGraph5_amc@nlo v2.2.2 program [27] hasbeenused to generate the γ +jet and W/Z+γ background MC samples at LO, withthe showering and hadronization carried out by the pythia _{8.212 program. A double counting of the partons} gener-atedwith MadGraph andthosewith pythia isremovedusingthe MLM [28] matchingscheme.ThemultijetMCeventsaregenerated using pythia 8.212eventgenerator.Thesameeventreconstruction isemployedindataandMCsimulations.However,thebackground isevaluatedfromdata,andtheMCsimulationisusedonlyforthe optimizationoftheeventselection.Theinvariantmassdistribution oftheSM γ+jet backgroundfallssmoothlyandcanbedescribed byananalyticfunction.

The inclusiveinvariant massdistribution andthedistributions for1b tagand0btagcategories, expressed in TeV, areshownin Figs. 2 and 3, respectively. The binning is chosen to have a bin widthapproximatelyequaltotheexpected γ+jet massresolution, whichvariesfromabout4.5%atamassof1 TeV to3.3%at6 TeV. These distributions are modeled using an empirical parametriza-tion that hasbeen usedwidely insimilar previous searches [7,8, 10,11]:

dσ

dm=

P0(1−m/√s)P1

(m/√s)P2+P3ln(m/√s) (2)

where √s=13TeV and P0, P1, P2, and P3 are four parameters

usedtodescribethebackgrounddistributionanditsnormalization. The order of the function hasbeen chosen by performing Fisher tests [29],withacut-offp-valueof0.05.Thefunction isfound to be ingood agreementwithdata witha χ2_{/ndf=40.7/41.4. The}

Fig. 3. Theγ+bjet invariantmassdistributionindata(blackpoints)usedforthe b_{analysis,afterfinalselectionfor(upper)1btagcategoryand(lower)0btag}

cat-egory.TheresultofthefittothedatausingtheparametrizationdefinedinEq. (2) isshownbytheblue dashedcurve withassociated bandsindicatingthe uncer-tainty.Thebin-by-binpull,(Data-Fit)/(stat.unc.),wherethedenominatorrefersto thestatisticaluncertaintyindata,isalsopresented.Thegreenandyellowbands correspond to1and2standarddeviations,respectivelyfromthemeanvalue. Simu-lationsofexcitedbquarksignalsrepresentingtheexpectedexcessofsignalevents overthebackgroundareshownforthe1band0btagcategoriesforthemassvalues of1.0and2.0 TeV forf=1.0.

highestinvariantmasseventobservedindatahasmγ+jetof4.6 TeV

withab-taggedjet,andthusbelongstoboththeinclusiveand1b tagcategories.

Inordertoexamine thepresenceofa possiblesystematicbias due to the choice of background fitting function, tests are per-formedusingalternate functionalforms.Thesealternative expres-sionsarepolynomialfunctionsthatalsoprovideadequate descrip-tions of the data.To perform these tests, an invariant mass dis-tribution ofthe SM background isobtained fromMC simulation. Thisinvariant massdistributionis fittedwithalternatetest func-tions and the results of the fit, considered as the truth model, areusedtogeneratealargenumberofpseudo-datasamplesthat havebin-to-binstatisticalfluctuationssimilartothoseofthedata.

Table 1

Summaryofthedominantsourcesofuncertaintiesandtheireffect onthesignalyield.

Source Effect on the signal yield (%) Integrated luminosity 2.5

Jet energy scale ∼1 Jet energy resolution 0.2–0.4 Photon energy scale ∼0.6 Photon energy resolution 0.2–0.4

Pileup 1–2 Photon ID efficiency ∼2 Trigger efficiency ∼5 Signal interpolation 0.5–1 PDF choice 1.5–3 b tag SF (only b_{) ∼1}

b tag SF normalization (only b_{) ∼2}

A signal with a cross section close to the expectedsensitivity is alsoinjected inthepseudo-datadistributions. Thesedistributions arethenfittedusingthedefaultbackgroundfunctionalongwitha signalmodel,andthesignalcrosssectionisextracted. Pull distri-butions definedasthedifference betweenthe trueandextracted signal cross sections divided by the estimated statistical uncer-tainty,forthe obtainedsignal crosssectionsare constructed.The deviationfromzero,ofthemeaninthepulldistribution,isa mea-sure ofthe bias presentin the model. The pull distributions for q _andb _{modeling overthe studiedmassrangearefound tobe} consistent withnormalizedGaussian forms withmedians deviat-ing by no more than 0.5 from zero, andwidths consistent with unityforthefullmassrange.Whenaddedinquadraturewiththe statisticaluncertainty, thebias uncertaintyis foundto contribute approximately10%ofthetotal.Therefore,itisconcludedthat the systematicuncertaintyassociatedwiththechoiceofthe paramet-ric functionis negligible,andthe statisticaluncertaintyofthe fit istheonlyuncertaintyinthebackgroundpredictionthatneedsto beconsidered.

5. Systematicuncertainties

Thedominantsourcesofthesystematicuncertaintiesaffecting theq_andb_{signalsaresummarizedin Table1.}

Theuncertaintiesinthejetenergyscaleandjetenergy resolu-tion [17] affectboth thesignalyieldanditsdistribution.Thesize oftheeffectisdeterminedbyvaryingthefour-momentaofthejets bythecorresponding uncertaintiesandrepeatingthefull analysis withthemodifiedquantities.

The systematic uncertainties in the photon energy scale and resolution, and photon identification efficiency are derived from Z→e+e− events. The uncertainty in the photon energy scale is found to be about 1% and it includes the uncertaintyin the ex-trapolationtohigherpT,beyondthereachoftheZ→e+e−control

samples [13]. Theuncertaintyinthephoton identificationis esti-mated tobe around 2%. Also, a systematicuncertaintyof 5% has been includedto account for the precision of thephoton trigger efficiencymeasurement.Theeffectofthebtaggingscale-factor un-certaintyonthedistributionofthesignalisevaluatedtobearound 1%whileonthenormalization,theeffectisaround2%.Themethod usedtointerpolatethesignaldistributionsfromthegenerated dis-tributions is assignedan uncertainty of0.5–1.0%, which accounts forthedifferencebetweenthegeneratedandinterpolatedsignals. The PDFuncertainty affectsthesignal acceptanceby 1.5–3.0%for bothq_andb_{quarksandisevaluatedusingPDF4LHC} recommen-dations [30].

The uncertainties inthe measurement ofthe integrated lumi-nosity (2.5%) [31] and pileup description (1%) affect the overall signal yield. The uncertainty in the background estimate is

ac-Fig. 4. Theobservedandexpectedupperlimitsat95%CLonσBasafunctionof themassoftheexcitedquark,for f=1.0.Thelimitsarecomparedwith theoret-icalpredictionsforexcitedquarkproductionforthreecouplings.Theinner(green) bandandtheouter(yellow)bandindicatetheregionscontaining68and95%, re-spectively,ofthemeanlimitsunderthebackground-onlyhypothesis.

countedforinthefitbyvaryingtheparametervalueswithintheir respectiveuncertainties,withnoadditionalconstraints.

6. Results

Inthemassregion studied,nosignificantexcess hasbeen ob-served.Weusethe γ+jet invariantmassspectra(Figs.2,3),the backgroundparametrization,andtheq andbtheoretical predic-tionstoset95%CLupperlimitsontheproductioncrosssectionof qandbdecayingtoqγ andbγ,respectively.

ThemodifiedfrequentistCLsmethod [32,33] intheasymptotic

approximation [34] isutilized to setupper limitsonsignal cross sections. The asymptotic approximation is found to be in good agreement withthe full CLs approximation over the entire mass

range. In order to evaluate limits, a likelihood function is con-structed that is the product of the Poisson likelihoods of all the binsinthedistribution.Thesystematicuncertaintiesinthesignal are implemented interms ofnuisance parameters withGaussian andlog-normalconstraints.Theuncertaintyduetothebackground parametrizationisfound to havethelargest impactandis quan-tified by considering the effect of changingthe parameters from theircentralvaluesbytheirestimated±1sigmauncertainties.We calculatelimitsbyevaluatingthelikelihoodindependentlyat suc-cessive values of resonance mass from 1 to 6 TeV for q_{, and 1} to 5 TeV for b _{in steps of 50 GeV. The cross section limits are} not evaluated below1 TeV, becauseof uncertainties inthe signal efficiency associated withthe invariant mass selection, mγ+jet>

700GeV.

In order to evaluate limits for b_{, likelihoods for 1b and 0b} tagcategoriesare combinedtogether.Theobserved andexpected mass limits for q _{and b} _{are computed at 95% CL. The results} are presentedintermsof limitsonthe productofthe cross sec-tion(σ)andbranchingfraction(B).Thecrosssectionupperlimits are compared to the LO theoretical predictions, for all the three couplings,to estimatethe lower masslimit onexcited quarks.In Figs. 4 and5,the experimental limits for f=1.0 areshown for qandb,respectively,withthetheoreticalpredictionsforthe dif-ferent couplings overlaid. There is a small dependenceof σ×B on f , of theorder of10%–20%, which is takeninto account cor-rectlywhenextractingthemasslimits.Observedlowerboundsof

Fig. 5. Theobservedandexpectedupperlimitsat95%CLonσBasafunctionof themassoftheexcitedbquark,for f=1.0.Thelimitsarecomparedwith the-oreticalpredictionsforexcitedbquarkproductionforthreecouplings.Theinner (green)bandandtheouter(yellow)bandindicatetheregionscontaining68and 95%,respectively,ofthemeanlimitsunderthebackground-onlyhypothesis.

Fig. 6. Theobservedandexpectedregionsexcludedat95%CLforq_andb

produc-tionanddecay,asafunctionofmq,mb and f .

5.5and1.8 TeV areobtainedforq_andb_{,respectively,for f=1.0.} Thecorresponding expectedmasslimitsobtainedare5.4(1.8) TeV for q (b). The variation of the excluded mass asa function of the coupling strength, obtained by interpolating the efficiencies forthree signal MCsamples correspondingto f =1.0,0.5, 0.1, is shownfor q _andb _{inFig.6.Thisresultcanalsobe interpreted} intermsoftheratiooftheresonancemassand,i.e.,ifwerelax the assumption of =mRes, the excited quark production cross

sectionisproportionalto f aswellasmRes/.

7. Summary

A search has been presentedfor excited states oflight and b quarks in γ+jet final states,usingdatacorresponding to an in-tegrated luminosity of 35.9 fb−1, collected at √s=13TeV. Upper limits at the 95% confidence level are placed on the product of productioncrosssectionanddecaybranchingfractionforthe

pres-enceofq_andb_{excitedquarksin γ+jet finalstates.Comparing} theseupperlimitswiththeoreticalpredictions,excitedlightquarks within the massrange 1.0<mq<5.5TeV and excited b quarks within the mass range 1.0<mb<1.8TeV are excluded at 95% confidencelevel,assumingstandardmodellikecouplingstrengths. Thesearethe mostsensitivelimitsforq _{and b} _{searchesinthe} γ+jet finalstates.Inaddition,thesearch forexcited bquarksis thefirsttobepresentedinanyfinalstateat√s=13TeV. Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrativestaffs atCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentersand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythecomputinginfrastructure essential toour analyses. Finally, we acknowledge the enduring support for the construc-tionandoperationofthe LHCandtheCMSdetectorprovided by 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);MOE andUM (Malaysia); BUAP,CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland);FCT(Portugal);JINR(Dubna);MON,ROSATOM,RAS,RFBR andRAEP (Russia);MESTD(Serbia); SEIDI,CPAN,PCTI andFEDER (Spain);SwissFundingAgencies(Switzerland);MST(Taipei); ThEP-Center, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey);NASUandSFFR(Ukraine);STFC (UnitedKingdom);DOE andNSF(USA).

Individuals have received support from the Marie-Curie pro-gramandtheEuropeanResearchCouncilandHorizon2020Grant, contract No. 675440 (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foun-dation;the BelgianFederal Science PolicyOffice; the Fonds pour laFormation àla Recherche dansl’Industrie etdans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Sci-ence and Industrial Research, India; the HOMING PLUS program of the Foundation for Polish Science, cofinanced from European Union,Regional DevelopmentFund, theMobilityPlus programof theMinistryofScienceandHigherEducation,theNationalScience 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-bis2012/07/E/ST2/01406;theNationalPriorities Re-search Program by Qatar National Research Fund; the Programa Severo Ochoa del Principado de Asturias; the Thalis and Aris-teia programs cofinanced by EU-ESF and the Greek NSRF; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chula-longkornUniversity andthe ChulalongkornAcademicintoIts 2nd CenturyProjectAdvancementProject (Thailand);theWelch Foun-dation,contractC-1845;andtheWestonHavensFoundation(USA). References

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TheCMSCollaboration

A.M. Sirunyan,A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, F. Ambrogi, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin,M. Dragicevic, J. Erö,M. Flechl, M. Friedl,R. Frühwirth1,V.M. Ghete, J. Grossmann, J. Hrubec, M. Jeitler1, A. König, N. Krammer,

I. Krätschmer,D. Liko, T. Madlener,I. Mikulec, E. Pree, N. Rad, H. Rohringer, J. Schieck1, R. Schöfbeck, M. Spanring, D. Spitzbart,W. Waltenberger, J. Wittmann, C.-E. Wulz1, M. Zarucki

InstitutfürHochenergiephysik,Wien,Austria

V. Chekhovsky, V. Mossolov,J. Suarez Gonzalez

InstituteforNuclearProblems,Minsk,Belarus

E.A. De Wolf,D. Di Croce, X. Janssen, J. Lauwers,M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel

UniversiteitAntwerpen,Antwerpen,Belgium

S. Abu Zeid,F. Blekman, J. D’Hondt, I. De Bruyn, J. De Clercq, K. Deroover, G. Flouris, D. Lontkovskyi, S. Lowette,I. Marchesini, S. Moortgat, L. Moreels,Q. Python, K. Skovpen, S. Tavernier, W. Van Doninck, P. Van Mulders, I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

D. Beghin, H. Brun, B. Clerbaux, G. De Lentdecker, H. Delannoy, B. Dorney,G. Fasanella, L. Favart, R. Goldouzian, A. Grebenyuk,T. Lenzi, J. Luetic, T. Maerschalk, A. Marinov,T. Seva, E. Starling, C. Vander Velde, P. Vanlaer, D. Vannerom,R. Yonamine, F. Zenoni, F. Zhang2

UniversitéLibredeBruxelles,Bruxelles,Belgium

A. Cimmino, T. Cornelis,D. Dobur, A. Fagot,M. Gul, I. Khvastunov3,D. Poyraz, C. Roskas, S. Salva, M. Tytgat, W. Verbeke,N. Zaganidis

GhentUniversity,Ghent,Belgium

H. Bakhshiansohi,O. Bondu, S. Brochet,G. Bruno, C. Caputo, A. Caudron, P. David, S. De Visscher, C. Delaere, M. Delcourt, B. Francois,A. Giammanco, M. Komm, G. Krintiras,V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, K. Piotrzkowski,L. Quertenmont, A. Saggio, M. Vidal Marono, S. Wertz,J. Zobec

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

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

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato4, E. Coelho, E.M. Da Costa, G.G. Da Silveira5, D. De Jesus Damiao,S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson, M. Melo De Almeida, C. Mora Herrera,L. Mundim,H. Nogima, L.J. Sanchez Rosas,A. Santoro, A. Sznajder,M. Thiel,

E.J. Tonelli Manganote4,F. Torres Da Silva De Araujo, A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

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

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

A. Aleksandrov, R. Hadjiiska,P. Iaydjiev, M. Misheva, M. Rodozov,M. Shopova, G. Sultanov

InstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Sofia,Bulgaria

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

UniversityofSofia,Sofia,Bulgaria

W. Fang6, X. Gao6,L. Yuan

BeihangUniversity,Beijing,China

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

InstituteofHighEnergyPhysics,Beijing,China

Y. Ban, G. Chen, J. Li,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,C.F. González Hernández, J.D. Ruiz Alvarez, M.A. Segura Delgado

UniversidaddeLosAndes,Bogota,Colombia

B. Courbon,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,B. Mesic, A. Starodumov7, T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

M.W. Ather,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

E. El-khateeb9,S. Elgammal10,A. Ellithi Kamel11

R.K. Dewanjee, M. Kadastik, L. Perrini, M. Raidal, A. Tiko, C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola, H. Kirschenmann,J. Pekkanen,M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Havukainen, J.K. Heikkilä, T. Järvinen,V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini,S. Laurila, S. Lehti, T. Lindén,P. Luukka, H. Siikonen, E. Tuominen, J. Tuominiemi

HelsinkiInstituteofPhysics,Helsinki,Finland

T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon, F. Couderc,M. Dejardin, D. Denegri, J.L. Faure, F. Ferri, S. Ganjour, S. Ghosh, P. Gras, G. Hamel de Monchenault, P. Jarry,I. Kucher, C. Leloup,E. Locci, M. Machet, J. Malcles,G. Negro, J. Rander, A. Rosowsky, M.Ö. Sahin,M. Titov

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

A. Abdulsalam, C. Amendola, I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro, C. Charlot, R. Granier de Cassagnac, M. Jo,S. Lisniak, A. Lobanov, J. Martin Blanco, M. Nguyen,C. Ochando,

G. Ortona,P. Paganini, P. Pigard,R. Salerno, J.B. Sauvan, Y. Sirois, A.G. Stahl Leiton, T. Strebler, Y. Yilmaz, A. Zabi, A. Zghiche

LaboratoireLeprince-Ringuet,Ecolepolytechnique,CNRS/IN2P3,UniversitéParis-Saclay,Palaiseau,France

J.-L. Agram12, J. Andrea, D. Bloch,J.-M. Brom, M. Buttignol,E.C. Chabert, N. Chanon, C. Collard, E. Conte12, X. Coubez, J.-C. Fontaine12,D. Gelé, U. Goerlach,M. Jansová, A.-C. Le Bihan, N. Tonon, P. Van Hove

UniversitédeStrasbourg,CNRS,IPHCUMR7178,F-67000Strasbourg,France

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,C. Bernet, G. Boudoul, R. Chierici,D. Contardo, P. Depasse, H. El Mamouni,J. Fay, L. Finco, S. Gascon, M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh,M. Lethuillier, L. Mirabito,

A.L. Pequegnot, S. Perries, A. Popov13,V. Sordini, M. Vander Donckt, S. Viret

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

A. Khvedelidze8

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze8

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann, L. Feld, M.K. Kiesel, K. Klein, M. Lipinski, M. Preuten,C. Schomakers, J. Schulz, V. Zhukov13

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

A. Albert, 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,T. Pook, M. Radziej, H. Reithler,M. Rieger, F. Scheuch,D. Teyssier, S. Thüer

G. Flügge,B. Kargoll, T. Kress,A. Künsken, T. Müller, A. Nehrkorn, A. Nowack,C. Pistone, O. Pooth, A. Stahl14

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,T. Arndt, C. Asawatangtrakuldee, K. Beernaert,O. Behnke, U. Behrens, A. Bermúdez Martínez, A.A. Bin Anuar, K. Borras15,V. Botta, A. Campbell,P. Connor,

C. Contreras-Campana, F. Costanza, C. Diez Pardos,G. Eckerlin, D. Eckstein, T. Eichhorn, E. Eren, E. Gallo16, J. Garay Garcia, A. Geiser, J.M. Grados Luyando, A. Grohsjean, P. Gunnellini, M. Guthoff, A. Harb,J. Hauk, M. Hempel17, H. Jung,M. Kasemann, J. Keaveney, C. Kleinwort,I. Korol, D. Krücker, W. Lange,A. Lelek, T. Lenz, J. Leonard,K. Lipka, W. Lohmann17,R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, E. Ntomari,D. Pitzl, A. Raspereza,M. Savitskyi,P. Saxena, R. Shevchenko,S. Spannagel, N. Stefaniuk, G.P. Van Onsem,R. Walsh, Y. Wen, K. Wichmann,C. Wissing, O. Zenaiev

DeutschesElektronen-Synchrotron,Hamburg,Germany

R. Aggleton,S. Bein, V. Blobel, M. Centis Vignali, T. Dreyer,E. Garutti, D. Gonzalez, J. Haller, A. Hinzmann, M. Hoffmann,A. Karavdina, R. Klanner, R. Kogler,N. Kovalchuk, S. Kurz, T. Lapsien, D. Marconi,M. Meyer, M. Niedziela, D. Nowatschin, F. Pantaleo14,T. Peiffer, A. Perieanu, C. Scharf, P. Schleper, A. Schmidt, S. Schumann,J. Schwandt,J. Sonneveld, H. Stadie,G. Steinbrück, F.M. Stober, M. Stöver,H. Tholen, D. Troendle, E. Usai, A. Vanhoefer, B. Vormwald

UniversityofHamburg,Hamburg,Germany

M. Akbiyik, C. Barth,M. Baselga,S. Baur, E. Butz, R. Caspart, T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm,N. Faltermann, B. Freund,R. Friese, M. Giffels,M.A. Harrendorf,F. Hartmann14, S.M. Heindl,U. Husemann, F. Kassel14, S. Kudella, H. Mildner, M.U. Mozer,Th. Müller, M. Plagge, G. Quast, K. Rabbertz,M. Schröder, I. Shvetsov,G. Sieber, H.J. Simonis, R. Ulrich, S. Wayand,M. Weber, T. Weiler, S. Williamson,C. Wöhrmann, R. Wolf

InstitutfürExperimentelleKernphysik,Karlsruhe,Germany

G. Anagnostou,G. Daskalakis, T. Geralis,A. Kyriakis, D. Loukas,I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

G. Karathanasis,S. Kesisoglou, A. Panagiotou, N. Saoulidou

NationalandKapodistrianUniversityofAthens,Athens,Greece

K. Kousouris

NationalTechnicalUniversityofAthens,Athens,Greece

I. Evangelou,C. Foudas, P. Gianneios, P. Katsoulis, P. Kokkas, S. Mallios,N. Manthos, I. Papadopoulos, E. Paradas, J. Strologas,F.A. Triantis, D. Tsitsonis

UniversityofIoánnina,Ioánnina,Greece

M. Csanad,N. Filipovic, G. Pasztor,O. Surányi, G.I. Veres18

MTA-ELTELendületCMSParticleandNuclearPhysicsGroup,EötvösLorándUniversity,Budapest,Hungary

G. Bencze,C. Hajdu, D. Horvath19, Á. Hunyadi, F. Sikler,V. Veszpremi

WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni,S. Czellar, J. Karancsi20,A. Makovec,J. Molnar, Z. Szillasi

M. Bartók18,P. Raics, Z.L. Trocsanyi, B. Ujvari

InstituteofPhysics,UniversityofDebrecen,Debrecen,Hungary

S. Choudhury, J.R. Komaragiri

IndianInstituteofScience(IISc),Bangalore,India

S. Bahinipati21, S. Bhowmik, P. Mal, K. Mandal, A. Nayak22, D.K. Sahoo21, N. Sahoo, S.K. Swain

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

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

PanjabUniversity,Chandigarh,India

Ashok Kumar, Aashaq Shah, A. Bhardwaj,S. Chauhan,B.C. Choudhary, R.B. Garg, S. Keshri,A. Kumar, S. Malhotra, M. Naimuddin,K. Ranjan, R. Sharma

UniversityofDelhi,Delhi,India

R. Bhardwaj,R. Bhattacharya, S. Bhattacharya, U. Bhawandeep, S. Dey,S. Dutt, S. Dutta, S. Ghosh,

N. Majumdar, A. Modak, K. Mondal, S. Mukhopadhyay, S. Nandan, A. Purohit,A. Roy, S. Roy Chowdhury, S. Sarkar,M. Sharan, S. Thakur

SahaInstituteofNuclearPhysics,HBNI,Kolkata,India

P.K. Behera

IndianInstituteofTechnologyMadras,Madras,India

R. Chudasama, D. Dutta, V. Jha,V. Kumar, A.K. Mohanty14,P.K. Netrakanti,L.M. Pant, P. Shukla,A. Topkar

BhabhaAtomicResearchCentre,Mumbai,India

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

TataInstituteofFundamentalResearch-A,Mumbai,India

S. Banerjee, S. Bhattacharya, S. Chatterjee,P. Das, M. Guchait, Sa. Jain, S. Kumar, M. Maity23, G. Majumder, K. Mazumdar,T. Sarkar23, N. Wickramage24

TataInstituteofFundamentalResearch-B,Mumbai,India

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

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

S. Chenarani25, E. Eskandari Tadavani,S.M. Etesami25,M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi26,F. Rezaei Hosseinabadi, B. Safarzadeh27,M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

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

M. De Palmaa,b, F. Erricoa,b, L. Fiorea, G. Iasellia,c, S. Lezkia,b, G. Maggia,c,M. Maggia, G. Minielloa,b, S. Mya,b, S. Nuzzoa,b,A. Pompilia,b,G. Pugliesea,c, R. Radognaa,A. Ranieria, G. Selvaggia,b, A. Sharmaa, L. Silvestrisa,14,R. Vendittia,P. Verwilligena

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

G. Abbiendia,C. Battilanaa,b,D. Bonacorsia,b, L. Borgonovia,b,S. Braibant-Giacomellia,b,

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

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

S. Albergoa,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,K. Chatterjeea,b,V. Ciullia,b,C. Civininia,R. D’Alessandroa,b, E. Focardia,b, P. Lenzia,b, M. Meschinia, S. Paolettia,L. Russoa,28,G. Sguazzonia,D. Stroma,L. Viliania,b,14

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

L. Benussi,S. Bianco, F. Fabbri, D. Piccolo,F. Primavera14

INFNLaboratoriNazionalidiFrascati,Frascati,Italy

V. Calvellia,b, F. Ferroa, F. Raveraa,b, E. Robuttia,S. Tosia,b

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

A. Benagliaa,A. Beschib,L. Brianzaa,b,F. Brivioa,b,V. Cirioloa,b,14, M.E. Dinardoa,b,S. Fiorendia,b, S. Gennaia,A. Ghezzia,b,P. Govonia,b,M. Malbertia,b,S. Malvezzia,R.A. Manzonia,b,D. Menascea, L. Moronia, M. Paganonia,b,K. Pauwelsa,b, D. Pedrinia,S. Pigazzinia,b,29,S. Ragazzia,b,

T. Tabarelli de Fatisa,b

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

S. Buontempoa, N. Cavalloa,c_{,S. Di Guida}a,d,14_{, F. Fabozzi}a,c_{,F. Fienga}a,b_{, A.O.M. Iorio}a,b_{,W.A. Khan}a_,

L. Listaa,S. Meolaa,d,14,P. Paoluccia,14,C. Sciaccaa,b,F. Thyssena

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

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

A. Carvalho Antunes De Oliveiraa,b,P. Checchiaa, P. De Castro Manzanoa,T. Dorigoa,U. Dossellia, F. Gasparinia,b, S. Lacapraraa,P. Lujan, M. Margonia,b, G. Marona,30, A.T. Meneguzzoa,b,N. Pozzobona,b, P. Ronchesea,b,R. Rossina,b,E. Torassaa,S. Venturaa,M. Zanettia,b, P. Zottoa,b, G. Zumerlea,b

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

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

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

L. Alunni Solestizia,b, M. Biasinia,b, G.M. Bileia,C. Cecchia,b,D. Ciangottinia,b, L. Fanòa,b,R. Leonardia,b, E. Manonia,G. Mantovania,b,V. Mariania,b,M. Menichellia, A. Rossia,b,A. Santocchiaa,b, D. Spigaa

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

K. Androsova,P. Azzurria,14,G. Bagliesia,T. Boccalia, L. Borrello, R. Castaldia, M.A. Cioccia,b, R. Dell’Orsoa,G. Fedia, L. Gianninia,c,A. Giassia, M.T. Grippoa,28, F. Ligabuea,c,T. Lomtadzea,

E. Mancaa,c,G. Mandorlia,c,A. Messineoa,b,F. Pallaa, A. Rizzia,b, A. Savoy-Navarroa,31, 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, M. Cipriania,b,N. Dacia, D. Del Rea,b,14, E. Di Marcoa,b,M. Diemoza, S. Gellia,b,E. Longoa,b,F. Margarolia,b,B. Marzocchia,b, P. Meridiania,G. Organtinia,b, R. Paramattia,b, F. Preiatoa,b,S. Rahatloua,b,C. Rovellia,F. Santanastasioa,b

a_{INFNSezionediRoma,Rome,Italy} b_{SapienzaUniversitàdiRoma,Rome,Italy}

N. Amapanea,b, R. Arcidiaconoa,c,S. Argiroa,b,M. Arneodoa,c,N. Bartosika,R. Bellana,b, C. Biinoa, N. Cartigliaa, F. Cennaa,b,M. Costaa,b, R. Covarellia,b,A. Deganoa,b,N. Demariaa, B. Kiania,b,

C. Mariottia, S. Masellia, E. Migliorea,b,V. Monacoa,b,E. Monteila,b,M. Montenoa, M.M. Obertinoa,b, L. Pachera,b, N. Pastronea,M. Pelliccionia,G.L. Pinna Angionia,b, A. Romeroa,b,M. Ruspaa,c, R. Sacchia,b, K. Shchelinaa,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,A. Zanettia

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

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

KyungpookNationalUniversity,Daegu,RepublicofKorea

A. Lee

ChonbukNationalUniversity,Jeonju,RepublicofKorea

H. Kim,D.H. Moon, G. Oh

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

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

HanyangUniversity,Seoul,RepublicofKorea

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

KoreaUniversity,Seoul,RepublicofKorea

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

SeoulNationalUniversity,Seoul,RepublicofKorea

H. Kim,J.H. Kim, J.S.H. Lee, I.C. Park

UniversityofSeoul,Seoul,RepublicofKorea

Y. Choi,C. Hwang, J. Lee, I. Yu

SungkyunkwanUniversity,Suwon,RepublicofKorea

VilniusUniversity,Vilnius,Lithuania

I. Ahmed,Z.A. Ibrahim, M.A.B. Md Ali32,F. Mohamad Idris33,W.A.T. Wan Abdullah, M.N. Yusli, Z. Zolkapli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

R. Reyes-Almanza,G. Ramirez-Sanchez, M.C. Duran-Osuna, H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-De La Cruz34, R.I. Rabadan-Trejo,R. Lopez-Fernandez, J. Mejia Guisao, A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

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

UniversidadIberoamericana,MexicoCity,Mexico

J. Eysermans,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, 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, M. Szleper, P. Zalewski

NationalCentreforNuclearResearch,Swierk,Poland

K. Bunkowski, A. Byszuk35,K. Doroba, A. Kalinowski, M. Konecki,J. Krolikowski, M. Misiura, M. Olszewski,A. Pyskir, M. Walczak

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

P. Bargassa,C. Beirão Da Cruz E Silva, A. Di Francesco, P. Faccioli,B. Galinhas, M. Gallinaro, J. Hollar, N. Leonardo,L. Lloret Iglesias, M.V. Nemallapudi, J. Seixas,G. Strong,O. Toldaiev, D. Vadruccio, J. Varela

LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal

V. Alexakhin,P. Bunin,A. Golunov, I. Golutvin, N. Gorbounov, A. Kamenev, V. Karjavin, A. Lanev, A. Malakhov,V. Matveev36,37, V. Palichik,V. Perelygin, M. Savina, S. Shmatov, S. Shulha, N. Skatchkov, V. Smirnov,A. Zarubin

JointInstituteforNuclearResearch,Dubna,Russia

Y. Ivanov,V. Kim38,E. Kuznetsova39, P. Levchenko,V. Murzin, V. Oreshkin, I. Smirnov, D. Sosnov, 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, A. Stepennov, M. Toms,E. Vlasov, A. Zhokin

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia

T. Aushev, A. Bylinkin37

MoscowInstituteofPhysicsandTechnology,Moscow,Russia

R. Chistov40,M. Danilov40,P. Parygin, D. Philippov,S. Polikarpov, E. Tarkovskii

NationalResearchNuclearUniversity‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

V. Andreev,M. Azarkin37, I. Dremin37,M. Kirakosyan37, A. Terkulov

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,V. Bunichev, M. Dubinin41,L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova,I. Lokhtin, I. Miagkov, S. Obraztsov,S. Petrushanko, V. Savrin

SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,Russia

V. Blinov42, Y. Skovpen42, D. Shtol42

NovosibirskStateUniversity(NSU),Novosibirsk,Russia

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

StateResearchCenterofRussianFederation,InstituteforHighEnergyPhysics,Protvino,Russia

P. Adzic43, P. Cirkovic, D. Devetak,M. Dordevic, J. Milosevic, V. Rekovic

UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia

J. Alcaraz Maestre, I. Bachiller,M. Barrio Luna, M. Cerrada,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,O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, D. Moran, A. Pérez-Calero Yzquierdo, J. Puerta Pelayo,

A. Quintario Olmeda, I. Redondo,L. Romero,M.S. Soares, A. Álvarez Fernández

CentrodeInvestigacionesEnergéticasMedioambientalesyTecnológicas(CIEMAT),Madrid,Spain

C. Albajar, J.F. de Trocóniz, M. Missiroli

UniversidadAutónomadeMadrid,Madrid,Spain

J. Cuevas, C. Erice,J. Fernandez Menendez, I. Gonzalez Caballero,J.R. González Fernández, E. Palencia Cortezon,S. Sanchez Cruz, P. Vischia, J.M. Vizan Garcia

UniversidaddeOviedo,Oviedo,Spain

I.J. Cabrillo, A. Calderon, B. Chazin Quero,E. Curras, J. Duarte Campderros, M. Fernandez,

J. Garcia-Ferrero,G. Gomez, A. Lopez Virto, J. Marco,C. Martinez Rivero, P. Martinez Ruiz del Arbol, 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, B. Akgun,E. Auffray, P. Baillon,A.H. Ball, D. Barney, J. Bendavid,M. Bianco, P. Bloch, A. Bocci, C. Botta, T. Camporesi, R. Castello, M. Cepeda, G. Cerminara, E. Chapon, Y. Chen, D. d’Enterria, A. Dabrowski,V. Daponte, A. David, M. De Gruttola, A. De Roeck, N. Deelen,M. Dobson, T. du Pree, M. Dünser,N. Dupont, A. Elliott-Peisert,P. Everaerts, F. Fallavollita,G. Franzoni, J. Fulcher, W. Funk,

D. Gigi,A. Gilbert, K. Gill,F. Glege, D. Gulhan, P. Harris, J. Hegeman, V. Innocente, A. Jafari,P. Janot, O. Karacheban17, J. Kieseler, V. Knünz,A. Kornmayer, M.J. Kortelainen, 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, P. Milenovic44,F. Moortgat, M. Mulders, H. Neugebauer, J. Ngadiuba, S. Orfanelli, L. Orsini,L. Pape, E. Perez,M. Peruzzi, A. Petrilli, G. Petrucciani,A. Pfeiffer,M. Pierini, D. Rabady, A. Racz,T. Reis, G. Rolandi45,M. Rovere, H. Sakulin,C. Schäfer, C. Schwick,M. Seidel, M. Selvaggi,A. Sharma,P. Silva, P. Sphicas46, A. Stakia,J. Steggemann,M. Stoye, M. Tosi, D. Treille,A. Triossi, A. Tsirou,V. Veckalns47, M. Verweij, W.D. Zeuner

CERN,EuropeanOrganizationforNuclearResearch,Geneva,Switzerland

W. Bertl†,L. Caminada48, K. Deiters,W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski, U. Langenegger,T. Rohe, S.A. Wiederkehr

PaulScherrerInstitut,Villigen,Switzerland

M. Backhaus,L. Bäni, P. Berger,L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Donegà, C. Dorfer, C. Grab,C. Heidegger, D. Hits, J. Hoss,G. Kasieczka, T. Klijnsma,W. Lustermann,B. Mangano,

M. Marionneau, M.T. Meinhard,D. Meister, F. Micheli,P. Musella, F. Nessi-Tedaldi, F. Pandolfi, J. Pata, F. Pauss,G. Perrin, L. Perrozzi,M. Quittnat, M. Reichmann,D.A. Sanz Becerra, M. Schönenberger, L. Shchutska, V.R. Tavolaro, K. Theofilatos, M.L. Vesterbacka Olsson, R. Wallny,D.H. Zhu

ETHZurich–InstituteforParticlePhysicsandAstrophysics(IPA),Zurich,Switzerland

T.K. Aarrestad, C. Amsler49, M.F. Canelli,A. De Cosa, R. Del Burgo, S. Donato, C. Galloni,T. Hreus, B. Kilminster,D. Pinna, G. Rauco, P. Robmann, D. Salerno, K. Schweiger, C. Seitz, Y. Takahashi, A. Zucchetta

UniversitätZürich,Zurich,Switzerland

V. Candelise,Y.H. Chang, K.y. Cheng,T.H. Doan, Sh. Jain,R. Khurana,C.M. Kuo, W. Lin,A. Pozdnyakov, S.S. Yu

NationalCentralUniversity,Chung-Li,Taiwan

Arun Kumar, P. Chang,Y. Chao, K.F. Chen, P.H. Chen, F. Fiori, W.-S. Hou, Y. Hsiung, Y.F. Liu,R.-S. Lu, E. Paganis, A. Psallidas,A. Steen, J.f. Tsai

NationalTaiwanUniversity(NTU),Taipei,Taiwan

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

ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

M.N. Bakirci50,A. Bat, F. Boran,S. Cerci51, S. Damarseckin, Z.S. Demiroglu, C. Dozen, E. Eskut, S. Girgis, G. Gokbulut,Y. Guler, I. Hos52, E.E. Kangal53,O. Kara, U. Kiminsu, M. Oglakci,G. Onengut54,

K. Ozdemir55,S. Ozturk50,A. Polatoz, U.G. Tok, S. Turkcapar, I.S. Zorbakir,C. Zorbilmez

ÇukurovaUniversity,PhysicsDepartment,ScienceandArtFaculty,Adana,Turkey

B. Bilin,G. Karapinar56, K. Ocalan57,M. Yalvac, M. Zeyrek

MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E. Gülmez,M. Kaya58,O. Kaya59, S. Tekten, E.A. Yetkin60

BogaziciUniversity,Istanbul,Turkey

M.N. Agaras,S. Atay, A. Cakir, K. Cankocak, I. Köseoglu

B. Grynyov

InstituteforScintillationMaterialsofNationalAcademyofScienceofUkraine,Kharkov,Ukraine

L. Levchuk

NationalScientificCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine

F. Ball,L. Beck, J.J. Brooke,D. Burns, E. Clement, D. Cussans,O. Davignon, H. Flacher,J. Goldstein, G.P. Heath, H.F. Heath,L. Kreczko, D.M. Newbold61,S. Paramesvaran, T. Sakuma,S. Seif El Nasr-storey, D. Smith,V.J. Smith

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell, A. Belyaev62, C. Brew, R.M. Brown, L. Calligaris, D. Cieri, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, J. Linacre,E. Olaiya, D. Petyt,C.H. Shepherd-Themistocleous, A. Thea,I.R. Tomalin, T. Williams

RutherfordAppletonLaboratory,Didcot,UnitedKingdom

G. Auzinger, R. Bainbridge,J. Borg,S. Breeze, O. Buchmuller, A. Bundock, S. Casasso,M. Citron, D. Colling, L. Corpe, P. Dauncey,G. Davies, A. De Wit, M. Della Negra, R. Di Maria, A. Elwood, Y. Haddad, G. Hall, G. Iles, T. James, R. Lane, C. Laner, L. Lyons, A.-M. Magnan, S. Malik,L. Mastrolorenzo, T. Matsushita, J. Nash, A. Nikitenko7, V. Palladino, M. Pesaresi,D.M. Raymond, A. Richards,A. Rose, E. Scott,C. Seez, A. Shtipliyski,S. Summers, A. Tapper,K. Uchida, M. Vazquez Acosta63,T. Virdee14,N. Wardle,

D. Winterbottom, J. Wright,S.C. Zenz

ImperialCollege,London,UnitedKingdom

J.E. Cole, P.R. Hobson, A. Khan,P. Kyberd, I.D. Reid, L. Teodorescu,S. Zahid

BrunelUniversity,Uxbridge,UnitedKingdom

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

BaylorUniversity,Waco,USA

R. Bartek, A. Dominguez

CatholicUniversityofAmerica,WashingtonDC,USA

A. Buccilli, 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, D. Cutts, A. Garabedian, M. Hadley,J. Hakala, U. Heintz, J.M. Hogan, K.H.M. Kwok,E. Laird, G. Landsberg, J. Lee,Z. Mao, M. Narain, J. Pazzini, S. Piperov,S. Sagir, R. Syarif, D. Yu

BrownUniversity,Providence,USA

R. Band,C. Brainerd, R. Breedon, D. Burns,M. Calderon De La Barca Sanchez, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher,C. Flores, G. Funk, W. Ko, R. Lander, C. Mclean, M. Mulhearn, D. Pellett, J. Pilot, S. Shalhout, M. Shi,J. Smith, D. Stolp, K. Tos, M. Tripathi,Z. Wang

UniversityofCalifornia,Davis,Davis,USA

M. Bachtis,C. Bravo, R. Cousins,A. Dasgupta, A. Florent,J. Hauser, M. Ignatenko, N. Mccoll, S. Regnard, D. Saltzberg, C. Schnaible, V. Valuev