Suppression of $\Upsilon(1S), \Upsilon(2S)$ and $\Upsilon(3S)$ production in PbPb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

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Physics

Letters

B

www.elsevier.com/locate/physletb

Suppression

of

ϒ

(1S),

ϒ

(2S),

and

ϒ(3S)

quarkonium

states

in

PbPb

collisions

at

√

s

=

2.76

TeV

Receivedinrevisedform26March2017 Accepted13April2017

Availableonline19April2017 Editor:M.Doser Keywords: CMS Physics Heavyions Dimuons Bottomonia

Theproductionyieldsofϒ(1S),ϒ(2S),andϒ(3S)quarkoniumstatesaremeasuredthroughtheirdecays intomuonpairsintheCMSdetector,inPbPbandppcollisionsatthecentre-of-massenergypernucleon pairof2.76 TeV.Thedatacorrespondtointegratedluminositiesof166μb−1and5.4pb−1forPbPband ppcollisions,respectively.Differentialproductioncrosssectionsarereportedasfunctionsofϒ rapidity y up to2.4,andtransversemomentum pTupto20GeV/c. Astrongcentrality-dependentsuppressionis

observedinPbPbrelativetoppcollisions,byfactorsofupto≈2 and8,fortheϒ(1S)andϒ(2S)states, respectively.Nosignificantdependenceofthissuppressionisobservedasafunctionof y or pT.Theϒ(3S)

stateisnotobservedinPbPbcollisions,whichcorrespondstoasuppressionforthecentrality-integrated databyatleastafactorof_≈7 ata95%confidencelevel.Theobservedsuppressionisinagreementwith theoreticalscenariosmodelingthesequentialmeltingofquarkoniumstatesinaquarkgluonplasma.

©2017TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3.

1. Introduction

Atlargeenergydensityandhightemperature,strongly interact-ingmatteris predictedby latticeQCD calculationstoconsist ofa deconfined systemofquarks andgluons[1].This state, often re-ferredtoas“quarkgluon plasma”(QGP)[2],constitutesthemain objectofstudiesusinghighenergyheavyioncollisions.

Theformation ofQGPin nuclearcollisions is studiedin a va-rietyofways.Oneofitsmoststrikingsignaturesisthesequential suppressionof quarkonium states,bothin thecharmonium (J/ψ,

ψ, χc,etc.)andthe bottomonium(ϒ(1S,2S,3S), χb,etc.)

fami-lies.Historically,thisphenomenonwasproposedasdirectevidence ofdeconfinementbecause,inthedeconfinedmedium,thebinding potentialbetweentheconstituentsofaquarkoniumstate,aheavy quark and its antiquark (QQ), should be screened by the colour chargesofthesurroundinglightquarksandgluons[3,4].The sup-pressionofquarkoniumproductionispredictedtooccurabovethe critical temperature of the medium (Tc) and to depend on the

QQ bindingenergy.Sincetheϒ(1S)isthemosttightlyboundstate amongall quarkonia, itis expectedto have thehighest dissocia-tiontemperature.Estimatesofdissociationtemperaturesaregiven in Ref. [5]: Tdissoc≈2Tc, 1.2Tc, and 1Tc for the ϒ(1S), ϒ(2S),

andϒ(3S) states,respectively.Other medium effects,such as re-generationfrom initially uncorrelatedquark–antiquark pairs [6,7]

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

orabsorptionbycomovingparticles [8,9]canmodifyquarkonium production in heavy ion collisions. Furthermore, nuclear effects such as modifications of parton distributions inside nuclei [10] or energy loss processes in nuclear matter [11] are expected to affecttheproductionofquarkonia independentlyofanyQGP for-mation.Anadmixtureofseveraloftheabove-mentionedeffectsin thecontextofbottomoniumproductionisinvestigatedinRefs.[12, 13] anda recentreview onquarkoniumproductioncan befound inRef.[14].

Thesuppressionofϒ(1S)productioninheavyioncollisions rel-ativetoppyieldsscaledbythenumberofbinarynucleon–nucleon (NN)collisionswasfirstmeasuredbyCMS[15]inthemidrapidity range |y|<2.4, then by ALICE atforward rapidities 2.5<y<4 [16]. Both measurements were done at the CERN LHC in PbPb collisions at a centre-of-mass energy per nucleon pair, √sNN, of

2.76TeV. A larger suppression of the ϒ(2S) and ϒ(3S) was first suggested [17] then observed [18] by CMS. In pPb collisions at √

sNN=5.02TeV,ALICE[19] andLHCb[20] reportedϒ(1S)yields

that are slightlysuppressed along the p-going forward direction, possibly indicating the importance of nuclear effects. Lackingpp reference data at √sNN=5.02TeV, the pp yields were estimated

by interpolating results at 2.76, 7, and 8 TeV [19], or by scaling data at8 TeV [20]. The ϒ(2S) and ϒ(3S) were reported by CMS to be slightly more suppressed than the ϒ(1S) ground state in pPbcollisions[21].AttheBNLRHIC,STARreportednosignificant suppressionoftheoverlappingϒ(1S+2S+3S)statesindAu colli-sionsat√sNN=200GeV,whileobservingasuppressionincentral

http://dx.doi.org/10.1016/j.physletb.2017.04.031

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

AuAucollisions atthesameenergy[22].Altogether, theseresults are interpreted asasequential suppression ofthe threestates in nucleus–nucleus collisions [12,13], with the tighter bound states disappearinglessintheQGP.

ThisLetterreportstheproductionyields ofϒ(1S), ϒ(2S),and

ϒ(3S) forPbPb andpp data atthe same √sNN=2.76TeV, using

integratedluminositiesof166μb−1 and5.4pb−1,respectively.The twosetsofdatacorrespondtoapproximatelythesamenumberof NNcollisions.Thepp sample collectedin2013contains 20times moreeventsthanthe2011datausedpreviously[15,17,18], allow-ingfurtherdifferentialstudieswithrespecttotheϒ meson rapid-ityandtransversemomentum.Muonreconstructionisimprovedin PbPbcollisionsrelativetoRef. [18],yieldinga35%increase inthe numberofmeasured ϒ candidates.In total,theimproved recon-struction anda relaxedmuon-pT selection provide almost twice

the numberof ϒ(1S) candidates used in Ref. [18].The yields in PbPb andppeventsare used toextract nuclearmodification fac-tors,RAA.

2. TheCMSdetector

AdetaileddescriptionoftheCMSdetector,togetherwitha def-inition ofthe coordinatesystemusedand therelevantkinematic variables,canbefoundinRef.[23].ThecentralfeatureoftheCMS apparatusisasuperconducting solenoidof6 minternal diameter. A silicontracker,acrystalelectromagneticcalorimeter,andabrass andscintillatorhadroncalorimeterresidewithinthemagneticfield volume.

Muons are detected in the pseudorapidity interval |η|<2.4 using gas-ionization detectors made of three technologies: drift tubes, cathodestrip chambers, andresistive-plate chambers, em-bedded in the steelflux-return yoke of the solenoid. The silicon trackeriscomposedofpixeldetectors(threebarrellayersandtwo forwarddisks on either side of the detector,made of66 million 100×150μm2 pixels)followedby microstrip detectors(ten barrel layers,andthreeinnerandnineforwarddisksoneithersideofthe detector,withstripsofpitchbetween80and180μm).The trans-versemomentumofmuonsmatchedtotracksreconstructedinthe silicondetectorismeasuredwitharesolutionbetterthan1.5%for pT valuessmallerthan100GeV/c [24].Thishighresolutionisthe

resultof the3.8 T magnetic field andthe highgranularity ofthe silicontracker.

In addition, CMS has extensive forward calorimetry, includ-ing two steel and quartz-fibre Cherenkov hadron forward (HF) calorimeters,that covertherange2.9<|η|<5.2.Thesedetectors areusedinthepresentanalysistoselecteventsandtodetermine thecentralityofPbPbcollisions,asdescribedinthenextsection.

3. Dataselections

3.1. Eventselectionandcentrality

ToselectpurelyinelastichadronicPbPbcollisions,contributions fromultraperipheralcollisionsandnoncollisionbeambackgrounds are removed, as described in Ref. [25]. Events are preselected if they containa primary vertexbuiltfromatleasttwo tracks,and atleastthreesignals(oneinthecaseofppcollisions)inHF tow-ersoneachsideoftheinteractionpointwithdepositedenergiesof atleast3 GeVineachtower.Tofurthersuppressbeam-gasevents, thedistributionofhitsinthepixeldetectoralongthebeam direc-tion is requiredto be compatible withparticles originating from the event vertex. These criteria select (97±3)% of the inelas-tic hadronicPbPb collisions [25], yielding an efficiency-corrected numberofminimumbias(MB) eventsNMB= (1.16±0.04)×109

for the MB sample corresponding to this analysis. The pp data

Table 1

Averagevaluesofthenumberofparticipatingnucleons(Npart,withthe

root-mean-squareofitsdistributionineachbin),andnuclearoverlapfunction(TAA,withits

systematicuncertainty)forthecentralitybinsusedinthe ϒ(1S)(upperrows)and

ϒ(2S)(middle)analyses.Thecentrality-integratedvaluesaregiveninthelastrow. Centrality (%) Npart(RMS) TAA(mb−1) 0–5 381 (19) 25.9±1.1 5–10 329 (22) 20.5±0.9 10–20 261 (30) 14.5±0.8 20–30 187 (23) 8.80±0.58 30–40 130 (18) 5.09±0.43 40–50 86.2 (13.6) 2.75±0.30 50–70 42.0 (14.4) 0.98±0.14 70–100 8.8 (6.0) 0.125±0.023 0–10 355 (33) 23.2±1.0 10–30 224 (46) 11.6±0.7 30–50 108 (27) 3.92±0.37 50–100 22.1 (19.3) 0.47±0.07 0–100 113 (115) 5.67±0.32

correspond to an integratedluminosity of5.4pb−1,known toan accuracy of 3.7% coming from the uncertainty in the calibration basedonavanderMeerscan[26].

Themeasurementsarebasedoneventsthatwerefirstselected bytheLevel-1trigger,ahardware-basedsystemthatuses informa-tionfromthemuondetectorsandcalorimeters.Thepresenceofat leasttwomuonswasrequired,withnoselectionappliedontheir momenta.Theeventswerethenfurtherfilteredusinga software-basedhigh-leveltrigger,andrejectedifmuonswerepoorly recon-structed, hence likely to be misidentified. The pp and PbPb data werecollectedusingthesametriggerlogic.

The centrality of PbPb collisions is defined as the fraction of the total number of inelastic hadronic collisions, with 0% repre-sentingcollisions withthe largestoverlapofthe twonuclei. This fractionisdeterminedfromthedistributionoftotalenergyinboth HF calorimeters. Variables related to the centrality, such as the number ofnucleons participating inthe collision (Npart) andthe

nuclearoverlapfunction(TAA)[27],areestimatedusingaGlauber

model simulation described in Ref. [25]. The value of TAA at a

given centrality is equal to the number of binary NN collisions dividedbytheNNcrosssectionandcanbeinterpretedasthe NN-equivalentintegratedluminosityperheavyioncollision.

It isto benotedthat thePbPb hadroniccrosssection (7.65± 0.42b)computedwiththisGlauber simulationcorresponds toan integratedluminosityof152±9μb−1,compatiblewithin1.2sigma withtheexperimentalvalueof166±8μb−1basedonthevander Meerscan.ThemeanvaluesofTAA andNpart arepresentedin

Ta-ble 1 for the narrow centrality bins used in the ϒ(1S) analysis, the wider bins used in the ϒ(2S) analysis, and the centrality-integrated estimate. The most peripheral bins are rather wide and, since quarkoniumyields scale withthenumber ofnucleon– nucleon collisions, most bottomonia are produced close to the most central edge of the bins, namely70% and 50%. The Npart

valuesshowninthefollowingfigures andreportedinTable 1are computedbyaveragingoverallMBeventsinagivencentralitybin, andarethereforenotcorrectedforanybiasintroducedby requir-ingthepresenceoftheϒ.Alsopresentedistheroot-mean-square (RMS)oftheNpartdistributionineachbin.TheuncertaintyonTAA

iscomputedbyvaryingtheGlauber parametersandtheevent se-lectioninefficiency,asdescribedinRef.[25].InthisLetter, Npart

is usedto show the centralitydependenceof themeasurements, while TAA directlyenters intothenuclearmodificationfactor

cal-culation: RAA=NPbPb/

 TAAσpp



whereNPbPb isthenumberofϒ

produced per PbPb collision in a given kinematic range and σpp

3.2.Muonselection

Muons are reconstructed using a global fit to a track in the muon detectorsthat ismatched to a trackin the silicontracker. TheofflinemuonreconstructionalgorithmusedforthePbPbdata has been improved relative to that used previously [18]. The efficiency has been increased by running multiple iterations in thepatternrecognitionstep, raisingthe numberofreconstructed

ϒ(1S)candidatesby approximately35%.Background muonsfrom cosmicrays andheavy-quarksemileptonic decaysare rejectedby imposing a set of selection criteria on each muon track. These criteriaare based on previous studies ofthe performance ofthe muonreconstructionalgorithm[28].Thetrackisrequiredtohave ahitinatleastonepixeldetectorlayer,andarespectivetransverse (longitudinal) distanceof closest approach of lessthan 3 (15) cm fromthe measuredprimary vertex,primarily toreject cosmicray muonsandmuonsfromhadrondecaysinflight.Toensureagood pT measurement,more than10hitsare requested inthetracker,

andthe χ2 _{per number of degrees offreedom of the trajectory}

fitsislimitedtobesmallerthan10whenusingthesilicontracker andthemuon detectors,andsmallerthan4whenusingonlythe tracker. Pairs of oppositely charged muons are considered when the χ2_{fitprobabilityofthetracksoriginatingfromacommon}

ver-texexceeds 1%.

Fortheϒ(2S) andϒ(3S) analyses, thetransverse momentum ofeach muon (pμ_T) is requiredto be above 4GeV/c,as in previ-ouspublications[15,17,18],whileoneofthemisrelaxeddownto 3.5GeV/c fortheϒ(1S)analysis.ReducingthispT thresholdraises

the ϒ(1S) yield by approximately 40%, andits statistical signifi-cance by up to 50%, depending on the pT and y ofthe dimuon

system.Relaxing thecriteriononthe secondmuon wasalso con-sideredthendiscarded, sinceit didnot significantlyraise the ac-ceptancefor the ϒ states. The resulting invariant mass distribu-tionsareshownonFig. 1fortheentireppandPbPbdatasamples.

4. Analysis

4.1.Signalextraction

Toextracttheϒ(1S),ϒ(2S),andϒ(3S)mesonyields,unbinned maximumlikelihoodfitstothe μ+μ− invariant massspectraare performedbetween7.5 and 14GeV/c2_{.Theresultsforthe p}

T-,

y-andcentrality-integratedcasearedisplayedassolidlinesonFig. 1. Eachϒ resonanceismodelledbythesumoftwoCrystalBall(CB) functions[29]withcommonmeanbutdifferentwidthstoaccount forthe pseudorapiditydependence ofthe muon momentum res-olution. The CB functionsare Gaussian resolution functionswith thelow-sidetailreplacedbyapowerlawdescribingfinal-state ra-diation.Thischoice was guided by simulationstudies, aswell as analyses of large pp event samplescollected at √s=7TeV [30]. Giventhe relatively large statisticaluncertainties, the only signal modelparameters thatareleft freeinthefitare themeanofthe

ϒ(1S)peak, andthe ϒ(1S), ϒ(2S) andϒ(3S) mesonyields. The other parameters,such asthewidth oftheϒ(1S)peak are fixed ineverybintothecorrespondingvalueobtainedfromsimulations. ThemeanandwidthoftheCBfunctionsdescribingtheϒ(2S)and

ϒ(3S)peaksare setby thefittedϒ(1S)peakmeanandthefixed

ϒ(1S) width, respectively, multipliedby the world-average mass ratio[31]. The parameters describing the tail ofthe CB function are fixed to values obtained from simulations, kept common in thethreeϒ states,then allowedtovarywhencomputingthe as-sociated systematic uncertainties. The background distribution is modelledbyanexponential functionmultipliedby anerror func-tion(theintegral ofaGaussian)describingthelow-massturn-on, withallparametersleftfreeinthefit.

Fig. 1. Dimuoninvariant massdistributions inpp(top)and centrality-integrated PbPb(bottom)dataat√sNN=2.76TeV,formuonpairshavingonepTgreaterthan

4GeV/c andtheothergreaterthan3.5GeV/c.Thesolid(signal+background)and dashed(backgroundonly)linesshowtheresultoffitsdescribedinthetext.

Withonemuon having pT greaterthan 4GeV/c andtheother

greaterthan3.5GeV/c,thisfittingprocedureresultsinϒ(1S) me-sonyieldsandstatisticaluncertaintiesof2534±76 and5014±87 in centrality-integratedPbPb andpp collisions, respectively. With bothmuons’transversemomentaabove4GeV/c,ityields173±41 forϒ(2S)and7±38 for ϒ(3S)(henceunobserved)inPbPb colli-sions,and1214±51 for ϒ(2S)and618±44 forϒ(3S) statesin ppcollisions.

4.2. Acceptanceandefficiency

To correct yields for acceptance and efficiency in the two data samples, thethree ϒ stateshave been simulated usingthe pythia 6.412 generator [32] andembedded in PbPb events sim-ulated with hydjet 1.8 [33], producing Monte Carlo (MC) events with the same settings as in Ref. [18], including radiative tails handled by photos [34]. Acceptanceis definedas thefraction of

ϒ in the |y|<2.4 range that decay into two muons, each with |ημ|<2.4,and pμ2

T >4GeV/c and p

μ1

T >3.5 or 4GeV/c for the

ϒ(1S) andϒ(2S)/ϒ (3S) states,respectively. Forthe ϒ(1S)state, theacceptanceovertheanalyzedphasespaceaveragesto35%.For allthreeϒ states,theacceptanceisconstantovermostofthe ra-pidity range, with a drop at large |y|. When the ϒ meson has

pT≈5GeV/c,the lower pT decaymuonoftenfallsbelowthe

re-quiredmomentumtoreachthemuondetector,resultinginadrop in acceptance for intermediate pT. For ϒ(2S) and ϒ(3S) states,

wherepTforbothmuonsisrequiredtobeabove4GeV/c,the

ac-ceptanceis 28 and33%, respectively.Within thisacceptance,the averagereconstructionandtriggerefficienciesare 68,74and75% forthe ϒ(1S), ϒ(2S),andϒ(3S)states,respectively. The slightly lowerefficiencyfortheϒ(1S)statearisesfromincludinglower-pT

muons,whichhavesmallerreconstruction efficiencies,in particu-laratmidrapidity.

The individual components of the efficiency are crosschecked using collision data andmuons from J/ψ meson decays, with a technique called tag-and-probe, similar to the one described in Ref. [30]. The method consists of fitting the J/ψ candidates in dataandMC samples,withandwithoutapplying theprobed se-lectioncriterion onone of the muons. The muon reconstruction, identification, and trigger efficiencies in the muon detectors are probed by testing the selection response in a sample collected with single-muon triggers. The small discrepancies observed be-tween the resultsfordata andsimulation are usedto determine pT- and η-dependent single-muoncorrection factorsthat are

ap-pliedtomuonsinthesimulation.Thenetcorrectionfactorstothe

ϒ meson yields range from 3 to 18%, the largest being located atlow pT orat large |y|.The trackerefficiency, larger than99%,

isalsoevaluated withthismethodby checkingthepresenceofa trackformuonsthat areprimarilyreconstructedinthemuon de-tectors. Thecorresponding uncertaintyis evaluated tobe 0.3and 0.6%foreachmuon,fortheppandPbPbdata,respectively. 4.3. Systematicuncertainties

Theuncertaintyfromthefittingprocedureisestimatedby per-formingsevenchangesinthefittingfunctions.Fiveofthemconsist ofreleasingone by onethe originallyfixed signal-shape parame-ters,toaccommodateforpossibleimperfectionsinthesimulation. Theothertwochangesconsistofaddingtothedefaultbackground functionafirst- orsecond-orderChebychev polynomial.The max-ima of the five signal and of the two backgroundvariations are summedinquadrature,yieldingsystematicuncertaintiesfrom4to 25% inthe PbPb data andfrom1 to10% in the pp data,forthe

ϒ(1S) mesonyield.Forthe lesssignificant ϒ(2S) signal, the un-certaintiesrangefrom13to71%inPbPb,andfrom1to15%inpp data.

Thesystematicuncertaintyfromthe acceptanceandefficiency estimationincludeschangesofthegeneratedpTand y spectra,as

wellasvariations ofthedistributionofϒ candidatesacrossevent centrality,withinlimitsimposedbythedatathemselves.Theseare propagatedintobin-by-binsystematicuncertaintiesof0.7and1.1% onaverage,inppandPbPbcollisions,respectively.

Single-muon efficiencies obtained from the tag-and-probe method are assigned a systematic uncertainty from varying re-quirements for the tag selection, the dimuon mass range, and the distributions of the invariant mass peak and the underlying backgrounds. The maximum deviation ineach pμ_T and ημ inter-val isretained asthe systematicuncertainty on the single-muon correction factors. Next, the single-muon correction factors are changedwithintheirstatisticaluncertaintiesderivedfromdata.To doso, onehundred variations ofthesingle-muonefficiencies are computed, resultingin one hundreddimuon efficiencycorrection factors in each analysis bin. The RMS of the resulting efficien-cies,summedinquadraturewiththesystematicuncertaintyinthe efficiency correction factors, represent the overall uncertainty in muonefficiency.Theresultingsystematicuncertaintiesrangefrom 3.2to7.7%frommidrapidityinpp collisionsto themostforward binsinPbPbcollisions.Inaddition,theuncertaintyinthetracking

Fig. 2. Differentialcrosssectionfor ϒstatesasafunctionoftheirtransverse mo-mentumandperunitofrapidityinpp(top)andPbPb(bottom)collisions.ThePbPb resultsareintegratedovercentralityanddividedbythenumberofelementaryNN collisions.Statistical(systematic)uncertaintiesaredisplayedaserrorbars(boxes). Globalrelativeuncertaintiesof3.7%(pp)and6.5%(PbPb)arenotdisplayed.

efficiencyof0.3and0.6%foreachtrackisconsideredasfully cor-related andthus doubled for dimuoncandidates, and takenasa globaluncertainty(commontoallpoints).

The relative uncertainties in the integrated luminosity of pp data (3.7%)or thenumberof PbPb MB events(3%) are also con-sideredasglobaluncertainties.TheuncertaintiesintheTAAvalues

aregiveninTable 1.

5. Results

5.1. Crosssections

Figs. 2 and 3show the differentialcross sectionsasfunctions of pT (perunit ofrapidity) and|y|,respectively, in pp (top)and

PbPb(bottom)collisions.Measuredyieldsarecorrectedforthe ac-ceptance andefficiency, then divided by thewidth of thebin in consideration.ToputtheppandPbPbdataonacomparablescale, the corrected yields are normalized by the measured integrated luminosity inpp collisions, andbythe productof thenumberof corresponding MB eventsandthe centrality-integrated TAA value

forPbPbcollisions.Thestatisticaluncertaintiesinppcollisions al-low a measurement forthe threestates usingthe samebinning: fivebinsinpTwithedgesat0,2.5,5.0,8.0,12.0,and20.0GeV/c,

Fig. 3. Differentialcrosssectionfor ϒstatesasafunctionoftheirrapidityand in-tegratedovertransversemomentuminpp(top)andPbPb(bottom)collisions.The PbPbresultsareintegratedovercentralityanddividedbythenumberof elemen-taryNNcollisions.Statistical(systematic)uncertaintiesaredisplayedaserrorbars (boxes).Globalrelativeuncertaintiesof3.7%(pp)and6.5%(PbPb)arenotdisplayed.

andsix equal bins in |y| from 0 to 2.4. In PbPb collisions, that samebinningcan beused fortheϒ(1S) analysis, butwiderbins arenecessaryintheϒ(2S)case:threebinsinpT withedgesat0,

5,12and20GeV/c,andtwobinsin y.Theϒ(3S)stateisnot ob-served inPbPb collisions, and an upperlimit is obtained forthe pT-, y- and centrality-integrated yield. The corresponding global

(fullycorrelated)uncertainties(notshownintheplots)includethe uncertaintyduetotheintegratedluminosityinppdata,the uncer-tainties dueto TAA andthe number ofMB eventsin PbPb data,

andtheuncertaintyinthetrackingefficiencyinbothcases. 5.2.Nuclearmodificationfactors

Nuclear modification factors, RAA, obtained by dividing the

PbPb yields by the product of the TAA values and the pp cross

sections,are shown on Fig. 4 as a function of the ϒ meson pT

(top) and |y| (bottom). The global (fully correlated) uncertainty hereincludestheuncertaintiesintrackingefficiency,theintegrated luminosity of the pp data, the number of MB PbPb events,and thecentrality-integrated TAA value. The RAA resultsshow a

sup-pression of a factor of ≈2 and 8 for ϒ(1S) and ϒ(2S) states, respectively. No pronounced dependence on the ϒ meson kine-maticsisobserved,thevaluesbeingconstantwithinuncertainties asafunctionofboth pT and y.

Fig. 4. Nuclearmodificationfactorfor ϒ(1S)and ϒ(2S)statesinPbPbcollisions asafunctionofpT(top)and|y|(bottom).Statistical(systematic)uncertaintiesare

displayedaserrorbars(boxes),whiletheglobal(fullycorrelated)uncertainty(7.5%) isdisplayedasagreyboxatunity.

Fig. 5 shows RAA asa function of centrality, displayed asthe

averagenumberofparticipatingnucleons,Npart.Theglobal(fully

correlated)uncertaintiescomefromtheuncertaintyintheppcross sections(which differforeach ϒ state),thenumberofMB PbPb collisions andthe PbPb tracking efficiency. The noticeable ϒ(1S)

centrality dependence, already observed in Ref. [18], is mapped out with more precision. As discussed in Section 3.1, points are displayedattheNpartvaluefoundbyaveragingoverallMBevents

ineachcentralityclass.Inthatrespect,itshouldbenotedthatthe largeϒ(2S)suppressionobservedforthe50–100%centralityrange spansa widerangeofNpart values,overwhichsuppressioncould

significantly change.The RAA valuesintegratedovercentralityfor

thethreeϒ statesareshowninthesidepanelofFig. 5.

The lack of observation ofthe ϒ(3S) state in PbPb data pro-videsanupperlimiton RAA,usingtheFeldman–Cousins

prescrip-tion[35].Thecentrality-integrated RAA valuesforthethreestates

are:

RAA(ϒ(1S))=0.453±0.014±0.046;

RAA(ϒ(2S))=0.119±0.028±0.015;

RAA(ϒ(3S)) <0.145 at a 95% confidence level,

withthefirstandseconduncertainties beingone standard devia-tionstatisticalandsystematic,respectively.

Fig. 5. Nuclearmodificationfactorsfor ϒ(1S)and ϒ(2S)mesonproductioninPbPb collisions,asafunctionofcentrality,displayedasthe averagenumberof partic-ipatingnucleons.Theupperlimitderivedonthe nuclearmodificationfactorfor

ϒ(3S)isrepresentedwith anarrowinthecentralityintegratedpanelat thefar right.Statistical(systematic)uncertaintiesaredisplayedaserrorbars(boxes),while theglobal(fullycorrelated)uncertaintiesfromthePbPbdata(3.2%)orfromthepp reference(6.3and6.9%for ϒ(1S)and ϒ(2S)states,respectively)aredisplayedat unityasempty,filled red,andfilledblackboxes,respectively.(Forinterpretation ofthereferencestocolourinthisfigurelegend,thereaderisreferredtotheweb versionofthisarticle.)

These observations are consistent with a sequential melting scenario forthe ϒ states,asdescribed in Refs. [12,36,37]. These models, which attribute most of the suppression to in-medium melting, do not predict a strong dependence of RAA on

rapid-ityortransverse momentum.Coldnuclear mattereffects such as PDF modifications and energy loss also do not exhibit such de-pendences, andtheir overallimpact on ϒ statesis muchsmaller than the observed suppression [11]. In contrast, quarkonium re-generation should depend significantly on pT, butit is predicted

tobesmallforbottomquarks[12].Thesequentialsuppressionby comovingparticles computed inRef. [38] reproduces the ϒ sup-pressioncentralitypattern,butanydependenceoneither pT or y

remainstobeassessed.

6. Summary

The ϒ(1S), ϒ(2S), and ϒ(3S) yields have been measured in PbPb andpp collisions at √sNN=2.76TeV with the CMS

detec-tor, using integrated luminosities of 166μb−1 and 5.4pb−1, re-spectively.Forthefirsttime,differentialproductioncrosssections are derived for individual ϒ states as functions of their rapid-ityandtransverse momentumin heavyion collisions.The ϒ(1S)

andϒ(2S) statesare suppressedinPbPb relative topp collisions scaledby thenumberofnucleon–nucleoncollisions, byfactorsof ≈2 and 8,respectively, while the absence of a significant ϒ(3S)

signalcorresponds toa suppressionbya factorlarger than≈7 at a 95% confidence level. While a strong centrality dependenceof thesuppressionisfoundfortheϒ(1S)andϒ(2S)states,noclear dependenceisobservedasafunctionofeithertransverse momen-tumorrapidity.Thelevelofsuppressionmeasuredinthisanalysis is compatiblewith theoretical models of a sequential meltingof quarkoniumstatesinahotmedium.

Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the

technical andadministrativestaffs atCERNand atother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentresand personneloftheWorldwideLHCComputingGridfordeliveringso effectively thecomputinginfrastructure essentialto our analyses. Finally, we acknowledge the enduring support for the construc-tion andoperationofthe LHCandtheCMSdetectorprovided by thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, 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, andUASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RASand RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TÜBITAK and TAEK (Turkey); NASU andSFFR(Ukraine);STFC(UnitedKingdom);DOEandNSF(USA).

Individuals have received support from the Marie-Curie pro-gramme andtheEuropean Research Council andEPLANET (Euro-peanUnion);theLeventisFoundation;theAlfredP.Sloan Founda-tion; the Alexander von Humboldt Foundation; the Belgian Fed-eral Science Policy Office; the Fonds pour la Formation à la Recherchedansl’Industrieetdansl’Agriculture(FRIA-Belgium);the AgentschapvoorInnovatiedoorWetenschapenTechnologie (IWT-Belgium); the MinistryofEducation, Youth andSports(MEYS) of theCzechRepublic;theCouncilofScienceandIndustrialResearch, India; the HOMING PLUSprogramme of the Foundation for Pol-ish Science, cofinanced from European Union, Regional Develop-ment Fund, the Mobility Plusprogramme ofthe Ministry of Sci-enceandHigher Education, theNationalScience Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2013/11/B/ST2/ 04202,2014/13/B/ST2/02543and2014/15/B/ST2/03998,Sonata-bis 2012/07/E/ST2/01406; the Thalis and Aristeia programmes cofi-nanced by EU-ESF and the Greek NSRF; the National Priorities ResearchProgrambyQatarNationalResearchFund;thePrograma Clarín-COFUNDdelPrincipadodeAsturias;theRachadapisek Som-pot Fund for Postdoctoral Fellowship, Chulalongkorn University andtheChulalongkornAcademicintoIts 2ndCenturyProject Ad-vancementProject(Thailand);andtheWelchFoundation,contract C-1845.

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TheCMSCollaboration

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. Waltenberger, C.-E. Wulz1

InstitutfürHochenergiephysik,Wien,Austria

O. Dvornikov,V. Makarenko, V. Zykunov

InstituteforNuclearProblems,Minsk,Belarus

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

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, 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, 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, D. Vannerom,R. Yonamine, F. Zenoni, F. Zhang2

UniversitéLibredeBruxelles,Bruxelles,Belgium

A. Cimmino, T. Cornelis,D. Dobur, A. Fagot,G. Garcia,M. Gul, I. Khvastunov, 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, G. Krintiras,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

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,B. Mesic, S. Micanovic, L. Sudic,T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

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

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

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

M. Kadastik, L. Perrini, M. Raidal, A. Tiko, C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,J. Pekkanen, M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Härkönen,T. Järvinen, 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

A. Abdulsalam, I. Antropov, F. Arleo,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,UniversitédeStrasbourg,UniversitédeHauteAlsaceMulhouse,CNRS/IN2P3,Strasbourg,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. 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

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

V. Cherepanov, G. Flügge, B. Kargoll, T. Kress, A. Künsken, J. Lingemann, T. Müller,A. Nehrkorn, A. Nowack,C. Pistone, O. Pooth,A. Stahl17

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,T. Arndt, 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

M. Akbiyik, C. Barth,S. Baur, C. Baus, J. Berger,E. Butz, R. Caspart,T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm,S. Fink, B. Freund,R. Friese, M. Giffels,A. Gilbert,P. Goldenzweig, D. Haitz, F. Hartmann17, S.M. Heindl,U. Husemann, I. Katkov15,S. Kudella, 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, 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, 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

UniversityofDebrecen,Debrecen,Hungary

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

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

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

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, S. Pandey, A. Rane, S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

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-Giacomelli}a,b_{, L. Brigliadori}a,b_{, R. Campanini}a,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,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,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. Brianzaa,b,17, M.E. Dinardoa,b,S. Fiorendia,b,17,S. Gennaia,A. Ghezzia,b, P. Govonia,b, M. Malberti, S. Malvezzia, R.A. Manzonia,b,17,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, F. Fiengaa,b, 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,N. Pozzobona,b,P. Ronchesea,b, F. Simonettoa,b,E. Torassaa, M. Zanetti, P. Zottoa,b_{, G. Zumerle}a,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. Pallaa,A. Rizzia,b,A. Savoy-Navarroa,33, 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, D. Del Rea,b,17, M. Diemoza, S. Gellia,b, E. Longoa,b, F. Margarolia,b, B. Marzocchia,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,F. Cennaa,b_{, M. Costa}a,b_{,R. Covarelli}a,b_{,A. Degano}a,b_{,N. Demaria}a_{, L. Finco}a,b_{, B. Kiani}a,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,F. Raveraa,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}

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,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,D.H. Moon

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

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

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

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, B. Calpas, 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

S. Afanasiev,P. Bunin, M. Gavrilenko,I. Golutvin, I. Gorbunov, A. Kamenev,V. Karjavin, A. Lanev,

A. Malakhov,V. Matveev38,39, V. Palichik,V. Perelygin, 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

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia

A. Bylinkin39

MoscowInstituteofPhysicsandTechnology,Russia

R. Chistov42, M. Danilov42,S. Polikarpov

NationalResearchNuclearUniversity‘MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

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

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,A. Demiyanov,A. Ershov, A. Gribushin, O. Kodolova,V. Korotkikh, I. Lokhtin,I. Miagkov, S. Obraztsov,S. Petrushanko, V. Savrin, A. Snigirev, I. Vardanyan

SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,Russia

V. Blinov43, Y. Skovpen43,D. Shtol43

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. Adzic44, 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 Marco45,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,P. Milenovic46,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,M. Verweij, 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

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, A. Zucchetta

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. Hos53, E.E. Kangal54,O. Kara, A. Kayis Topaksu,U. Kiminsu,M. Oglakci, G. Onengut55, K. Ozdemir56,D. Sunar Cerci52, B. Tali52,S. Turkcapar, I.S. Zorbakir, C. Zorbilmez

CukurovaUniversity,Adana,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

NationalScientificCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine

R. Aggleton,F. Ball, L. Beck, J.J. Brooke, D. Burns,E. Clement, D. Cussans, H. Flacher,J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath,J. Jacob, L. Kreczko, C. Lucas, D.M. Newbold64, S. Paramesvaran, A. Poll, T. Sakuma,S. Seif El Nasr-storey, D. Smith,V.J. Smith

UniversityofBristol,Bristol,UnitedKingdom

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

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

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, K.H.M. Kwok, 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

UniversityofCalifornia,Davis,Davis,USA

C. Bravo,R. Cousins, A. Dasgupta, P. Everaerts, A. Florent, J. Hauser, M. Ignatenko,N. Mccoll, D. Saltzberg, C. Schnaible, 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, I. Macneill,D. Olivito, S. Padhi, M. Pieri, M. Sani, V. Sharma, S. Simon, M. Tadel,A. Vartak,

S. Wasserbaech67,C. Welke, J. Wood, F. Würthwein,A. Yagil, G. Zevi Della Porta

UniversityofCalifornia,SanDiego,LaJolla,USA

N. Amin, R. Bhandari,J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta, M. Franco Sevilla, C. George, F. Golf, L. Gouskos,J. Gran, R. Heller, J. Incandela,S.D. Mullin, A. Ovcharova,H. Qu, J. Richman, D. Stuart, I. Suarez,J. Yoo

UniversityofCalifornia,SantaBarbara,DepartmentofPhysics,SantaBarbara,USA

D. Anderson,A. Apresyan, J. Bendavid,A. Bornheim, J. Bunn, Y. Chen,J. Duarte, J.M. Lawhorn,A. Mott, H.B. Newman, C. Pena,M. Spiropulu, J.R. Vlimant, S. Xie, R.Y. Zhu

CaliforniaInstituteofTechnology,Pasadena,USA

M.B. Andrews,V. Azzolini, T. Ferguson, M. Paulini, J. Russ, M. Sun, H. Vogel, I. Vorobiev,M. Weinberg

CarnegieMellonUniversity,Pittsburgh,USA

J.P. Cumalat, W.T. Ford,F. Jensen, A. Johnson, M. Krohn,T. Mulholland, K. Stenson, S.R. Wagner