Transverse momentum spectra of inclusive b jets in pPb collisions atv root s(NN)=5.02 TeV

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DOI: 10.1016/j.physletb.2016.01.010

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©2016 by Elsevier. All rights reserved.

DIRETORIA DE TRATAMENTO DA INFORMAÇÃO Cidade Universitária Zeferino Vaz Barão Geraldo

CEP 13083-970 – Campinas SP Fone: (19) 3521-6493 http://www.repositorio.unicamp.br

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Transverse

momentum

spectra

of

inclusive

b

jets

in

pPb

collisions

at

√

s

=

5.02 TeV

Receivedinrevisedform10January2016 Accepted12January2016

Availableonline14January2016 Editor:M.Doser Keywords: CMS Physics Heavyions b-tagging

Wepresent ameasurement ofbjettransversemomentum(pT)spectrainproton-lead (pPb)collisions

usingadatasetcorrespondingtoabout35 nb−1collectedwiththeCMSdetectorattheLHC.Jetsfromb quarkfragmentationarefoundbyexploitingthelonglifetimeofhadronscontainingabquarkthrough tagging methods using distributions of the secondaryvertex mass and displacement. Extracted cross sectionsforbjetsarescaledbytheeffectivenumberofnucleon–nucleoncollisionsandarecomparedto areferenceobtainedfrom pythia simulationsofppcollisions.The pythia-basedestimateofthenuclear modificationfactorisfoundtobe1.22±0.15(stat+syst pPb)±0.27(syst pythia) averagedoveralljets withpTbetween55and400 GeV/c andwith|ηlab| <2.Wealsocomparethisresulttopredictionsfrom

modelsusingperturbativecalculationsinquantumchromodynamics.

©2016CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.Thisisanopenaccess articleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

By colliding heavy nuclei at ultra-relativistic energies, suffi-cientlylarge energy densitiesare reached toform aquark–gluon plasma(QGP),astatewhichischaracterizedbyaneffective decon-finementofquarks andgluons[1,2].Hard-scattered partonshave beenpredictedtosufferenergylossastheytraversetheQGP, pri-marilyviacollisionalandradiativeprocesses[3,4].Thisenergyloss iscommonlythoughttobethemechanismresponsibleforthe ob-served suppression of high transverse momentum (pT) hadrons and jets in nucleus–nucleus collisions relative to proton–proton (pp) collisions [5,6]. This suppression phenomenon, otherwise knownas“jetquenching”,wasdiscoveredattheRHICexperiments atBNL[7–14]andhasbeeninvestigatedfurtherusingfully recon-structed jetsat the CERN LHC [15–18]. Studies of partonenergy lossareexpectedtorevealthefundamentalpropertiesoftheQGP. The quenching of jets in heavy ion collisions should depend on the flavor of the fragmenting parton [5]. For example,under theassumptionthatradiativeenergylossisthedominant mecha-nism,gluonjetsareexpectedtoquenchmorestronglythanquark jets, owing to the larger color factor for gluon emission from gluonsthan from quarks [19]. There are also theoretical predic-tions that radiative energy loss may not be dominant for heavy quarks,includingmodelsbasedoncollisionalenergylossofquarks within the medium and models favoring an interpretation based

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

onmesonicrecombinationanddisassociationwithinthemedium, e.g. Refs. [20,21].It isexpectedthat thereshould be some mass-dependenceofpartonicenergylossatlowmomentum,and there-fore,b quark jet (b jet)energy lossmight be differentfromthat oflightquark jets[22,23].At high-pT,however,theCMS Collabo-ration hasshownthatbjetsuppressioninPbPbisconsistentwith thatoflightquarkjetsabove80 GeV/c[16].

Here we present the first measurement of inclusive b-tagged jetsinproton-lead(pPb)collisions.ThismeasurementinpPb pro-vides the first direct evidence that the jet quenching observed in PbPb is dominated by final-state effects, rather than poten-tialnuclearinitial-stateeffects.Furthermore,thesemeasurements will provide a factorization of cold nuclear matter effects from the medium suppression effects for jets in PbPb collisions. Such a differentiation betweeninitial-state andquenching effects asa functionofflavorcanplaceconstraintsontheenergyloss mecha-nismsofpartonsinthehotanddensemedium.Thisisespecially importantinlightoftheCMSmeasurementofthenuclear modifi-cationfactorofchargedparticlesinpPbcollisions,whichindicates surprisinglylargeinitial-stateeffects[24].

Measurements of dijets in pPb have also shown that a theo-retical description ofdijet yields as a function of pseudorapidity requiresnext-to-leadingordereffectswithcontributionsfrom nu-clear partondistribution functions (nPDFs) [25,26]. While pythia simulations predict weak correlationsof Björken-x andsingle jet pseudorapidity,weinvestigatethepseudorapidity-dependent mod-ificationfactorinordertoprobeforthepresenceofstrong unan-ticipated effects in the heavy flavor sector. Any effects would http://dx.doi.org/10.1016/j.physletb.2016.01.010

0370-2693/©2016CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

depend predominantlyonthegluonnPDFs,anareawhichhasalso beenexploredtheoretically[27].Thisisincontrasttotheprevious dijetmeasurement,whereleadingorderquarkjetprocesseshavea significantcontributiontothemeasurement,especiallyathigh-pT. WepresentmeasurementsofbjetproductioninpPbcollisions ata nucleon–nucleoncenter-of-massenergyof √sNN=5.02 TeV, recordedwiththeCMSdetector,usinganintegratedluminosityof about35 nb−1 deliveredbytheLHC.Thecrosssectionforbjetsis measuredandcomparedtopp crosssectionssimulatedusingthe pythiaeventgenerator[28],tuneZ2[29].Theresultingestimated nuclearmodificationfactors(RPYTHIA_pA )arecomparedtoaprediction basedonperturbativeQCD(pQCD)[30].

2. Detectorandeventselection

The CMS detector has excellent capabilities to perform b jet identification (b tagging) as demonstrated in Ref. [31]. The cen-tral feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Withinthe solenoid volume are a silicon pixel andstrip tracker, aleadtungstatecrystalelectromagneticcalorimeter(ECAL), anda brass and scintillator hadron calorimeter(HCAL), each composed of a barrel and two endcap sections. The tracker has a pseu-dorapidity coverage of |ηlab| <2.4, while the calorimetry covers

|ηlab| <3.Muonsaremeasuredingas-ionizationdetectors embed-dedin the steel flux-return yoke outsidethe solenoid. Extensive forward calorimetry complements the coverage provided by the barrel and endcap detectors. A more detailed description of the CMS detector, together with a definition of the coordinate sys-tem used and the relevant kinematic variables, can be found in Ref.[32].

The event selection is identical to previous pPb jet analy-ses [24,25], and includes the reconstruction of a primary inter-action vertex, a careful removal of any noise artifacts from the hadroniccalorimeter, along witha requirement that the primary interactionvertexiswithin15 cm ofthenominalinteractionpoint alongthebeamaxis.

In this analysisa newtrigger combinationalgorithm is used, allowing forthe maximization ofstatisticalprecision over a very large range of jet pT. Triggers with thresholds ranging from 20 through 100 GeV/care combined.Except forthe 100 GeV/c trig-ger, these triggers are prescaled, meaning only a fraction of the total numberof events are recorded. Ineach event, the jet with themaximumonlinerawjetpT (i.e. thelargestjetpT seenbyany ofthefive triggers)isfound. Ifthehighest-threshold triggerthat shouldhaveidentifiedthejetisabsent(prescaledaway),thewhole eventis rejected. Otherwise, all jets in the eventare assigneda weightbasedontheprescalevalueofthathighest-threshold trig-ger.Theresultingspectrumisfullyefficientabove≈30 GeV/c.

As described,e.g. in Ref.[25],thedifference in the charge-to-massratioofprotonsandleadnucleiresultsinasymmetricbeam energies for the two colliding species, which leads to a rapidity shiftof 0.465 unitsbetweenthe nucleon–nucleon center-of-mass frameandthelaboratory frame.Inaddition,after thedata corre-spondingtoanintegratedluminosityof20.9 nb−1 werecollected, thecirculation directionsof theproton andlead beamswere re-versed. This analysis will use ηCM for the center-of-mass frame and ηlab forthelabframepseudorapidities,wherepositive ηwill always refer tothe beamorientation where theproton beam di-rectionistowardpositivez.Inthisorientation, ηlab=ηCM+0.465. Thisanalysisrequiresthatalljetsmusthave−2.5<ηCM<1.5, whichensures that all jetsfragment primarily within the tracker acceptanceof|ηlab| <2.4.Finally,thebackgroundenergyfromthe underlyingpPbeventis estimatedinnarrowranges of pseudora-pidity, as described in Ref. [33], and is subtracted from the jet.

After the underlying event subtraction, jets must have a recon-structed pT>55 GeV/c andaraw transversemomentum(before jet energycorrections)greaterthan25 GeV/c andmustbe found in an event where a single-jet trigger fires. This requirement is madeinordertoproperlymergeeventsfrommultipletriggers,as discussedearlierinthissection.

In order to estimate the kinematic and resolution properties of jets, simulated dijet eventsare generatedwith pythia version 6.424, tune Z2[28].Thesedijets are thenembedded intoa min-imum bias pPb backgroundevent simulatedby the hijing heavy ioneventgenerator,version1.383[34].

3. Analysisprocedure

3.1. Jetreconstruction

Jetsarereconstructedofflineprimarilyfromtheenergydeposits in thecalorimetertowers,clusteredby theanti-kT algorithm [35,

36] with a size parameter of 0.3. The constituent particles of the jet arereconstructed usingthe particleflow eventalgorithm, which identifies each individual particlewith an optimized com-bination of information from the various elements of the CMS detector[37].Therawjetenergyisobtainedfromthesumofthe tower energies,andthe rawjet momentumby thevectorialsum oftheconstituentparticlemomenta,whichresultsinanonzerojet mass. Theraw jetenergies are then correctedto establisha uni-form response of the calorimeter in η and a calibrated absolute responsein pT.Thefinalparticle-flow-basedjetenergyresolution amounts typically to 15% at 10 GeV, 8% at 100 GeV, and 4% at 1 TeV, tobecomparedto about40%, 12%,and5% obtainedwhen thecalorimetersaloneareusedforjetclustering.

Jetenergycorrectionsarederivedfromsimulation,andare con-firmed within situmeasurements of theenergy balance indijet and photon+jet events. Jet momentum is found from simula-tion to be within 1% to 2% of the true jet momentum over the whole pT spectrumanddetectoracceptanceusedinthisanalysis. Additional selection criteriaare applied to each event to remove spurious jet-like features originating fromisolated noise patterns incertainHCALregions.

3.2. Taggingbjets

Identificationofbjetsisbasedonkinematicvariablesrelatedto the relativelylong lifetimeandlargemass ofB hadrons.Charged tracks associatedwithjetsareused toreconstructsecondary ver-ticesfromBhadronand/orsubsequentcharmhadrondecaysfrom the b→ ccascade. The primary discriminator usedin this anal-ysisto identifybjetstakesadvantage ofthedisplacedsecondary vertex. This secondaryvertex basedalgorithm iscalledthe “sim-ple secondary vertex” (SSV) tagger and is described in detail in Ref. [31].Effectively,jetsareassignedadiscriminatorvalue based on the secondaryvertexflight distance significance,whichis the ratio of the distance between the primary and secondary vertex toits uncertainty.Toremoveadditionalcontributionsofjetsfrom longlivedlightmesons,secondaryvertexmassescompatiblewith the K0_S meson and displacements larger than 2.5 cm are explic-itlyrejected. Usingthisdiscriminator, thecontributionofbjetsis enhancedbyrequiringthatsecondaryverticesarefarfromthe pri-maryvertex.TheSSVselectionvalueusedinthisanalysisis 2.0, re-quiringthatthesecondaryvertexistwostandarddeviationsaway from the primary vertex. This is chosen to give a misidentifica-tionrateontheorderof1%forlight-flavorjetsand10%forcharm jets, based on simulation. The corresponding b taggingefficiency is about65% for both pp andpPb collisions, whichuse identical reconstruction procedures. This is in contrast to the PbPb b jet

Fig. 1. DistributionsoftheJPtaggerdiscriminatorbefore(top)andafter(bottom) applyingthe SSVtaggerselection.Filledblackpointsaredata,whilethe colored histogramsdenotecontributionsfromsimulatedb,c,andlight-flavorjetsinred, greenand blue,respectively,obtainedfromafit todata.Statisticaluncertainties fromdataareinblack,whilestatisticaluncertaintyfromthetemplatesareshown indarkgreen.(Forinterpretationofthereferencestocolorinthisfigurelegend,the readerisreferredtothewebversionofthisarticle.)

analysisatCMSwhere the btagging efficiencyisabout 45% due totheneedforadedicatedregionaltrackreconstructionowingto theverylargemultiplicitiesreachedincentralcollisions[16].

The b tagging efficiency is obtained by simply counting the numbers of b jets before andafter tagging in simulation,but is cross-checkedusing a data-driven method from the output of a secondbtaggingalgorithm:thejetprobability(JP)algorithm.The advantageofthissecond taggeris thatit doesnot relyupon the reconstruction of a secondary vertex[31]. Instead, the JP tagger calculates the compatibility of each track in the jet cone with the primary vertex using a probability distribution based on the three-dimensional impact parameter significance. In essence, the less compatible the jet tracks are with the primary vertex, the greater the likelihood of the jet being from a b quark fragmen-tation. Tracksmay alsohave anegative impactparameter, which ariseswhentheyarefoundtobedisplacedfromtheprimary ver-texon the opposite side ofthe vertexfromthe jet. Thesetracks mainlycomefromprimaryparticleswithanimproperlymeasured impact parameter due to finite vertex resolution effects or from poorlymeasuredtrackkinematicparameters.Sincethesetypesof tracksareessentiallyrandomlyassociatedwiththevertex,theyare notusedtotagjets, butinsteadcan beusedtocalibrate the tag-ger.Randomlyassociatedtracksshouldhavenocorrelationtothe vertexas a function of displacement,so the total distribution of thesetracksasafunctionoftrackdisplacementshouldbeflat.Ifit isnot,thetaggeriscalibratedbyapplyingaweightingfunctionin ordertoflattenthespectrum[31].OncetheJPtaggeriscalibrated, discriminator values are obtained by calculating the sum of the

Fig. 2. Thetop panelshowsthelikelihoodofmisidentifyingalight-flavor(circles anddottedlines)orcharm(squaresanddashedlines)jetasabjet,asafunction ofthebtaggingefficiency.ShownistheSSVtaggerforpPb(purple)andpp(green) collisions.Thebottom panelshowsatemplatefittothesecondaryvertex invari-antmassdistributioninpPbcollisionsforjetswith90<pT<110 GeV/c.Filled

blackpointsaredata,whilethecoloredhistogramsdenotedistributionsofb,c,and light-quarkjetsinred,greenandblue,respectively,extractedfromthefittodata. Statisticaluncertaintiesfromdataareshownasblackverticalbars,while statisti-caluncertaintiesfromthetemplatesareshownasdarkgreenverticalbarsaround thesumofthetemplates.(Forinterpretationofthereferencestocolorinthisfigure legend,thereaderisreferredtothewebversionofthisarticle.)

negative logarithm of all track-to-vertex probabilities, normalized bythefactorialofthenumberoftracksassociatedwiththejet.

Distributions ofthe JP tagger discriminator are plotted before andafter applying theSSV selection definedearlier. Byusing an unbinnedmaximumlikelihoodfittotheJPdistributions,thethree flavorcontributionsfromsimulationsaresimultaneouslyfittothe data.Fromthesefits,theSSVbtaggingefficiencycanbeextracted basedon Eq.(1),where Cb isthe fractionofb jetsfrom

simula-tionthathaveaJPdiscriminatorvalue, f_btagged isthepurityofthe SSV >2taggedsample, f_buntagged isthepuritybeforetagging,and

Nuntagged_jets and Ntagged_jets are thenumberofjetsbefore andafterthe SSVselection,respectively.

S S V=

CbfbtaggedN

tagged jets

f_buntaggedN_jetsuntagged. (1)

ExampledistributionsoftheJPtaggerdiscriminatorbeforeand afterSSVtaggingintherange90<pT<110 GeV/c areshownin

Fig. 1.TheefficiencyfoundbyapplyingtheSSVtaggertoJP-tagged eventsindataandcalculatingtheefficiencydirectlyfrom simula-tionarecompatibletowithin5–20%,wherethedifferenceistaken asasystematicuncertainty.

Thebtagging efficiencyoftheSSV taggerisshownasa func-tion ofthemisidentificationprobability oflight-flavor andcharm jetson theleft inFig. 2.The efficiencyandpurityofthe taggers

areverysimilarinppandpPbcollisionsduetotheidentical recon-structionmethodologyusedforbothcollisiontypes.ThoughtheJP taggerhas ahigher btagging efficiencythan the SSV taggerdue tothe fact that theJP taggerdoesnot requirethe existence ofa secondary vertex, the SSV taggeris the primary method ofb jet identificationin this analysisfor two reasons.First, the SSV tag-geris morerobust against light-flavor andcharm jet background duetothesecondaryvertexrequirement.Second,theJPtaggercan becalibratedagainst data,whichisessential toprovidinga data-drivenestimateofthebtaggingefficiency,thereforetheJPtagger isbettersuitedasareferencethantheSSVtagger.

Foreachjet pT bin,thebjetpurityisextractedviaatemplate fit.Foreachsecondary vertex,an invariant massiscalculated us-ing the individual track energies and momenta. Then, secondary vertex mass distributions from light, charm, and b jets in the pythia+hijingsimulationare fittothoseindata.Theshapesof the differentflavor components ofthe distributions are fixed via theMonteCarlosimulations(MC),buttherelativenormalizations ofeach componentare allowed to float independently. While all jetflavorshavesignificantcontributions,the bjetcontributionto the secondary vertex mass dominates above about 2 GeV/c2_, al-lowing foran accurate fit to data. An example of such fittingis shownontherightinFig. 2.

Foreach tagger,ab jetyield can becalculated foragiven pT bin: Nb=N fb/,where Nb isthe numberofb-taggedjets, fb is thepurityofthesample,derived fromthesecondaryvertexmass fits, and  is the tagger efficiency, determined from simulation. After tagging, the jet resolution effects on the b jet pT spectra are unfolded using a singular value decomposition (SVD) matrix inversionprocedure[38],asimplementedinthe RooUnfold pack-age[39]. The pPbspectra are normalized by the total integrated luminosity (35 nb−1) and divided by the mass number of lead (A=208), which is the effective enhancement of jet production duetogeometricaleffectsfromtheheaviernuclei,aspredictedby theGlaubermodel[40].

RPYTHIA_pA = 1 A d2σ_jetpA/dpTdη d2_σPYTHIA jet /dpTdη . (2)

The formula used to calculate the nuclear modification factor (RPYTHIA_pA ) isdefinedinEq.(2).The ηCM-dependent RPYTHIA_pA is ob-tainedbydividingthejetcrosssectioninpPb(scaledwiththelead ionmass,A)bythejetcrosssectionobtainedfromappreference. Asthereisnoppdataavailableat√sNN=5.02 TeV,thisreference isobtainedfroma pythia calculation“σPYTHIA

jet ”.

4. Systematicuncertainties

ThesystematicuncertaintiesofthepPbyieldfallintofour gen-eralcategories:btagging,jetreconstruction,andscaling uncertain-tiesduetounfoldingandtheluminosityuncertainty.Thebtagging uncertainties have five primary subcomponents. The first source ofuncertaintycomesfromthedifferencebetweencalculatingthe efficiency()usingtheJPtagger(Eq.(1))[31]andextracting  di-rectlyfromsimulation.Thisisthedominantsystematicuncertainty at high pT and accounts for about 50% of the total uncertainty. A secondsourceisobtainedbyvaryingtheSSVtagger discrimina-torselectionsuchthat  differsbyabout10%,whichaccountsfor about35%ofthetotalsystematicuncertaintyforjet pTlargerthan about100 GeV/c and10% below100 GeV/c.Next,the charmjet normalizationisfixed tothe light-flavor jet normalization,rather than allowing it to float independently in the template fits. This accountsforabout7% ofthetotaluncertaintyandisindependent ofpT.Fourth,adata-derived(charm+light)backgroundtemplate produced from jets with small JP values is used. This

contribu-tion is roughly 5% of the total uncertaintyfor jet pT larger than 100 GeV/c and 50% below 100 GeV/c. The final tagging uncer-tainty is found byvarying the gluon splittingcontributionin the bandcjettemplates by50%. Thisisthesmallestcontributionto the total systematicuncertainty (5%).The total systematic uncer-taintyonthebjettaggingvariesfromabout15to20%depending on thejet pT.The uncertaintyisevaluated viathequadraticsum ofall systematicvariationsofthetaggingprocedure,which influ-encetheextractedbtaggingpurityandefficiencyvalues.

The jet reconstruction procedure has uncertainties totaling around8–15%forthepPbspectrastemmingfromclosuretests be-tween dataandMC.Theseuncertaintiesarisefromthejetenergy resolution (JER) and jet energy scale (JES). The resolution uncer-taintyisabout10%,whichdecreasesasafunctionofjet pT,while thescaleuncertaintyisabout3–4%,depending onjet pT.The un-certainty stemmingfromthejet unfoldingprocedureisevaluated by varying the SVD regularization parameter and the presumed prior spectrum. The pPb to pp normalization has about 5% un-certainty due to the unfolding. Finally, the uncertainty on the pPbintegratedluminosity is3.6%[41].Theseuncertaintiesare all summedinquadraturewiththetagginguncertaintiestoobtainthe totaluncertaintyonthepPbbjetspectra.

The pp reference crosssection has two sources ofsystematic uncertainty.As noppdataat5 TeV exist yet,andsincethere are too few published measurements of b jet cross section to allow for an interpolated reference, we are forced to rely on simula-tion, but can make some reasonable assumptions regarding the expected agreement of the simulated reference withdata. These two sources of uncertainty are a 20% uncertainty based on the discrepancybetweenexistingbjetmeasurementsand pythia sim-ulationsat2.76[16]and7 TeV[42],anda8.5%uncertaintybased onthebjetcrosssectiondifferencebetweentheZ2andD6T[43] pythiatunes. The discrepancies between pythia anddataat2.76 and 7 TeV are roughly constant in pT and η, except for the pT region well belowthereach ofthisanalysis, wherethedeviation becomes quite large.The data-to-simulationdiscrepancyisadded inquadraturewiththedifferencebetweentheD6TandZ2tunepT distributionsatboth2.76and7 TeV sothatthedifferenceintune isaccountedforintheoverallppuncertainty.This22% overallpp uncertaintyisshownastheredband aroundunityinFig. 3(right panel)andinFig. 5.

Lastly,thejetandbtaggingsystematicuncertaintiesforRPYTHIA_pA

are obtainedby varyingthe pPbdata simultaneouslywiththe pp simulation inordertoensure anycorrelatedsystematicsare can-celledout.Apartialcancellationoftheuncertaintiesexists,butas thegeneratorvaluesareusedfortheppreferenceintheanalysis, the residual pPb unfoldinguncertainties donot cancel, aswould be the casewithapp measurement fromdata.It shouldalsobe noted that due to the template fitting procedure and unfolding, thereisapartialcorrelationbetweenthestatisticalandsystematic uncertaintiesforthe η-dependentresult.

5. Results

The b jet pT spectra in pPb are shown on the left in Fig. 3 for several ηCM selections, along with cross sections from the pythiappreference(histograms).Weobserveconsistencybetween the pPb data and the pythia pp reference, indicating a lack of

η-dependent effects.Thiscanbe madeexplicitby calculatingthe

RPYTHIA_pA foreach ηCMselection,asdefinedinEq.(2).Therightside ofFig. 3showsthe RPYTHIA

pA measurementsforthesamefour ηCM selections as on the left. The average values are consistent with unitywithinuncertainties.

The b jet fraction can be extracted by dividing the b jet cross section by the inclusive jet cross section. This is shown

Fig. 3. ThebjetcrosssectionasafunctionofpTisshownforvarious

pseudorapid-ityselectionsforpPbcollisions,scaledbythemassnumberoflead(filledboxes), andcomparedto pythia predictionsofbjet crosssectionsinppshownasbare histogramsontheleft.Inaddition,RPYTHIA

pA measurementsforthesamefourηCM

rangesareshownontheright.Positiveηcorrespondstothedirectionoftheproton beam.Statisticaluncertaintiesarerepresentedusingverticalbars,whilesystematic uncertaintiesareshownascoloredbandsontheleftandfilledboxesontheright. Theppreferenceuncertaintiesareshownseparatelyasredboxesaroundunityon therightpanel.(Forinterpretationofthereferencestocolorinthisfigurelegend, thereaderisreferredtothewebversionofthisarticle.)

in Fig. 4, where we observe consistent results between the pPb data and the pythia simulation within systematic uncertainties. These systematic uncertainties are calculated by noting that the uncertainties fromthe jetenergy scale,unfolding procedure, and the luminosity are highly correlated between the samples with

Fig. 4. ThebjetfractionisshownforpPbdataasfilledblackcirclessurrounded byfilledboxesforsystematicuncertainties,whicharehighlycorrelatedtothebjet

RPYTHIA

pA uncertainties.AsimulationfromtheZ2tuneofpythia+hijingat

√

sNN=

5.02 TeV isalsoshownasopenblueboxes.(Forinterpretationofthereferencesto colorinthisfigurelegend,thereaderisreferredtothewebversionofthisarticle.)

Fig. 5. ThebjetRPYTHIA

pA asafunctionofjetpTisshownaspointswithfilledboxes

forsystematicuncertainties.Theppreferenceandintegratedluminosity uncertain-tiesareshownasredandgreenbandsaroundunity,respectively.ApQCDprediction fromHuangetal.[30]isalsoshown.(Forinterpretationofthereferencestocolor inthisfigurelegend,thereaderisreferredtothewebversionofthisarticle.) and without implementing b tagging, and we therefore assign the b tagging uncertainties as the total uncertainty on the frac-tion.

Fig. 5 shows the pseudorapidity-integrated RPYTHIA

pA . Fitting a constant to thisdistribution returns a value of RPYTHIA_pA =1.22± 0.15(stat+syst pPb)±0.27(syst pythia),whichindicatesthatthe bjetyieldinpPbisconsistentwiththepp pythia simulation, espe-ciallyconsideringthe22%uncertaintyonjustthe pythia reference. The measurementdoesnot,however,excludean enhancement in

RpA as large as the one observed in the charged particle mea-surementfromCMSathighpT [24].Inaddition,Fig. 5showsthe comparisonof themeasured RPYTHIA

pA to predictionsfroma pQCD model that includes modest initial-state energy-loss effects [30] andconservativeuncertainties stemmingfromtheunknown frac-tionofjetsthatcontainacollimatedbb pairoriginatingfromgluon splitting.Themodelanddataareroughlyconsistentwithinthe to-talsystematicuncertaintiesfromboth pythia andthepPbdata.

This result can be compared to the recent study of B me-son productionin pPbfrom theCMS Collaboration[44].We find good agreement betweenthe two analyses,noting that the bjet

RPYTHIA

Bmesons overthe entiretyofthe 10–60 GeV/c pT rangeused in themesonanalysis.

6. Conclusions

In summary, the first measurements of b jet production at 5.02 TeV havebeenpresentedovera pT rangefrom55–400 GeV/c andapseudorapiditywindow of−2.5<ηCM<1.5.Theobserved valueofRPYTHIA_pA =1.22±0.15(stat+syst pPb)±0.27(syst pythia) providesthe firstdirect evidencethat coldnuclear mattereffects donotplayamajorroleinjetquenchinginthePbPbsystem. Fur-thermore,asizeablejetproductionenhancementfromcoldnuclear mattereffectsisnotexpectedatsuchlargepT,aconclusionwhich thedatasupports.Wefindthatthepseudorapidity-integratedand pseudorapidity-dependent RPYTHIA

pA valuesareconsistentbothwith unityandwiththeenhancementobservedbyCMSforcharged par-ticlesathighpT.

Theconsistencywithunityasafunctionofpseudorapidity indi-catesthatverylargenPDFeffectsdonotexistinthegluonsector, anobservationwhichisconsistentwiththeoreticalmodels.While thecurrentconstraintsonthegluonnPDFsarenotverytightdue to presentsystematicuncertainties, thismeasurement provides a baselineforfuturestudies,especiallythosethatuseatrueproton– protonsample asareferencepoint.Studiesofback-to-backbjets, forexample,willprovidesignificantconstraintsonthesenPDF ef-fectsduetothetightercorrelationofpseudorapidityandBjörken-x andtherestriction ofb jet productionto primarily leading order processes.

Overall, these results provide a baseline for the study of in-medium b quark energy loss inPbPb collisions. Future measure-ments ofbjetsinpp collisions at5.02 TeV willreduce thelarge systematicuncertainties fromthecurrent pythia reference, allow-ing foramoreprecise measurementofb jetenergymodification inpPbcollisions.

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,wegratefullyacknowledgethecomputingcentresand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythe computinginfrastructureessential to ouranalyses. Finally, we acknowledge the enduring support for the construc-tionandoperation oftheLHCandthe CMSdetectorprovidedby thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES(Bulgaria);CERN;CAS,MOST,andNSFC(China);COLCIENCIAS (Colombia);MSESandCSF(Croatia);RPF(Cyprus);MoER,ERCIUT andERDF(Estonia);Academy ofFinland,MEC,andHIP(Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM(Malaysia); CINVESTAV, CONACYT,SEP,andUASLP-FAI(Mexico);MBIE(NewZealand);PAEC (Pakistan);MSHEandNSC(Poland);FCT(Portugal);JINR(Dubna); MON,RosAtom,RASandRFBR(Russia);MESTD(Serbia);SEIDIand CPAN(Spain);SwissFundingAgencies(Switzerland);MST(Taipei); ThEPCenter,IPST,STARandNSTDA(Thailand);TUBITAKandTAEK (Turkey);NASUandSFFR(Ukraine); STFC(United Kingdom);DOE andNSF(USA).

Individuals have received support from the Marie-Curie pro-grammeandthe European ResearchCouncil 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 Ministry of Education, Youth and Sports (MEYS) of the Czech Republic;the Council of Science andIndustrial Re-search, India; the HOMING PLUS programme of the Foundation forPolish Science,cofinancedfromEuropeanUnion, Regional De-velopment Fund; the OPUS programme of the National Science Centre (Poland); the Compagnia di San Paolo (Torino); the Con-sorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); theThalisandAristeiaprogrammescofinancedbyEU-ESFandthe Greek NSRF; the National Priorities Research Program by Qatar NationalResearch Fund;theRachadapisekSompot Fund for Post-doctoral Fellowship,Chulalongkorn University (Thailand);andthe WelchFoundation,contractC-1845.

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CMSCollaboration

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,V. Knünz, A. König,

M. Krammer1, I. Krätschmer,D. Liko, T. Matsushita,I. Mikulec, D. Rabady2,B. Rahbaran, H. Rohringer,

J. Schieck1, R. Schöfbeck, J. Strauss, W. Treberer-Treberspurg,W. Waltenberger, C.-E. Wulz1

InstitutfürHochenergiephysikderOeAW,Wien,Austria

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

NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

S. Alderweireldt, T. Cornelis,E.A. De Wolf,X. Janssen, A. Knutsson,J. Lauwers, S. Luyckx, S. Ochesanu,

R. Rougny, M. Van De Klundert,H. Van Haevermaet, P. Van Mechelen, N. Van Remortel,A. Van Spilbeeck

UniversiteitAntwerpen,Antwerpen,Belgium

S. Abu Zeid,F. Blekman, J. D’Hondt, N. Daci,I. De Bruyn, K. Deroover, N. Heracleous,J. Keaveney,

S. Lowette,L. Moreels,A. Olbrechts, Q. Python, D. Strom, S. Tavernier,W. Van Doninck, P. Van Mulders,

G.P. Van Onsem,I. Van Parijs

P. Barria, H. Brun, C. Caillol, B. Clerbaux, G. De Lentdecker, H. Delannoy, G. Fasanella, L. Favart,

A.P.R. Gay, A. Grebenyuk,G. Karapostoli, T. Lenzi,A. Léonard, T. Maerschalk,A. Marinov, L. Perniè,

A. Randle-conde,T. Reis, T. Seva,C. Vander Velde, P. Vanlaer,R. Yonamine, F. Zenoni, F. Zhang3

UniversitéLibredeBruxelles,Bruxelles,Belgium

K. Beernaert,L. Benucci, A. Cimmino, S. Crucy, D. Dobur, A. Fagot,G. Garcia,M. Gul, J. Mccartin,

A.A. Ocampo Rios, D. Poyraz,D. Ryckbosch, S. Salva, M. Sigamani, N. Strobbe,M. Tytgat,

W. Van Driessche, E. Yazgan, N. Zaganidis

GhentUniversity,Ghent,Belgium

S. Basegmez, C. Beluffi4,O. Bondu,S. Brochet, G. Bruno, R. Castello, A. Caudron, L. Ceard,

G.G. Da Silveira,C. Delaere, D. Favart,L. Forthomme,A. Giammanco5,J. Hollar, A. Jafari,P. Jez,M. Komm,

V. Lemaitre, A. Mertens, C. Nuttens, L. Perrini, A. Pin, K. Piotrzkowski,A. Popov6,L. Quertenmont,

M. Selvaggi,M. Vidal Marono

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

N. Beliy, G.H. Hammad

UniversitédeMons,Mons,Belgium

W.L. Aldá Júnior, G.A. Alves,L. Brito, M. Correa Martins Junior,M. Hamer,C. Hensel, C. Mora Herrera,

A. Moraes,M.E. Pol, P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato7,A. Custódio, E.M. Da Costa,

D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson,

D. Matos Figueiredo, L. Mundim,H. Nogima, W.L. Prado Da Silva, A. Santoro, A. Sznajder,

E.J. Tonelli Manganote7,A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahujaa, C.A. Bernardesb, A. De Souza Santosb,S. Dograa, T.R. Fernandez Perez Tomeia,

E.M. Gregoresb, P.G. Mercadanteb,C.S. Moona,8,S.F. Novaesa,Sandra S. Padulaa,D. Romero Abada,

J.C. Ruiz Vargasa

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

M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen,M. Chen, T. Cheng, R. Du,C.H. Jiang, R. Plestina9,F. Romeo,

S.M. Shaheen, J. Tao, C. Wang,Z. Wang, H. Zhang

InstituteofHighEnergyPhysics,Beijing,China

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

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

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

UniversidaddeLosAndes,Bogota,Colombia

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

Z. Antunovic,M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

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

InstituteRudjerBoskovic,Zagreb,Croatia

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

UniversityofCyprus,Nicosia,Cyprus

M. Bodlak,M. Finger10, M. Finger Jr.10

CharlesUniversity,Prague,CzechRepublic

A.A. Abdelalim11,12,Y. Assran13,A. Awad14,15,M. El Sawy16,15, A. Mahrous11, A. Radi15,14

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

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

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,J. Pekkanen, M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

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

T. Mäenpää,T. Peltola, E. Tuominen, 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,

A. Givernaud, P. Gras, G. Hamel de Monchenault,P. Jarry, E. Locci, M. Machet,J. Malcles, J. Rander,

A. Rosowsky,M. Titov, A. Zghiche

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

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

O. Davignon,N. Filipovic, A. Florent, R. Granier de Cassagnac,S. Lisniak, L. Mastrolorenzo, P. Miné,

I.N. Naranjo,M. Nguyen, C. Ochando, G. Ortona, P. Paganini,P. Pigard, S. Regnard, R. Salerno,J.B. Sauvan,

Y. Sirois,T. Strebler, Y. Yilmaz, A. Zabi

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

J.-L. Agram17,J. Andrea, A. Aubin,D. Bloch, J.-M. Brom,M. Buttignol, E.C. Chabert,N. Chanon, C. Collard,

E. Conte17,X. Coubez, J.-C. Fontaine17, D. Gelé, U. Goerlach,C. Goetzmann, A.-C. Le Bihan, J.A. Merlin2,

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, B. Ille, F. Lagarde,

I.B. Laktineh,M. Lethuillier, L. Mirabito,A.L. Pequegnot, S. Perries, J.D. Ruiz Alvarez,D. Sabes,

L. Sgandurra,V. Sordini, M. Vander Donckt, P. Verdier,S. Viret, H. Xiao

T. Toriashvili18

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze10

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann, S. Beranek,M. Edelhoff,L. Feld, A. Heister, M.K. Kiesel, K. Klein, M. Lipinski, A. Ostapchuk,

M. Preuten,F. Raupach, S. Schael,J.F. Schulte, T. Verlage,H. Weber, B. Wittmer, V. Zhukov6

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

M. Ata, M. Brodski,E. Dietz-Laursonn, D. Duchardt, M. Endres, M. Erdmann,S. Erdweg, T. Esch,

R. Fischer,A. Güth, T. Hebbeker, C. Heidemann, K. Hoepfner,D. Klingebiel, S. Knutzen,P. Kreuzer,

M. Merschmeyer,A. Meyer, P. Millet, M. Olschewski, K. Padeken,P. Papacz, T. Pook,M. Radziej,

H. Reithler,M. Rieger, F. Scheuch,L. Sonnenschein, D. Teyssier, S. Thüer

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

V. Cherepanov, Y. Erdogan,G. Flügge, H. Geenen, M. Geisler, F. Hoehle, B. Kargoll, T. Kress, Y. Kuessel,

A. Künsken, J. Lingemann2,A. Nehrkorn, A. Nowack,I.M. Nugent,C. Pistone, O. Pooth,A. Stahl

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,I. Asin, N. Bartosik, O. Behnke, U. Behrens,A.J. Bell, K. Borras, A. Burgmeier,A. Cakir,

L. Calligaris, A. Campbell,S. Choudhury, F. Costanza, C. Diez Pardos, G. Dolinska,S. Dooling,T. Dorland,

G. Eckerlin, D. Eckstein, T. Eichhorn, G. Flucke,E. Gallo19, J. Garay Garcia, A. Geiser, A. Gizhko,

P. Gunnellini, J. Hauk, M. Hempel20, H. Jung,A. Kalogeropoulos, O. Karacheban20, M. Kasemann,

P. Katsas, J. Kieseler, C. Kleinwort,I. Korol, W. Lange, J. Leonard, K. Lipka,A. Lobanov, W. Lohmann20,

R. Mankel, I. Marfin20,I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller,

S. Naumann-Emme,A. Nayak, E. Ntomari,H. Perrey, D. Pitzl,R. Placakyte, A. Raspereza, B. Roland,

M.Ö. Sahin,P. Saxena, T. Schoerner-Sadenius,M. Schröder, C. Seitz,S. Spannagel, K.D. Trippkewitz,

R. Walsh, C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

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

M. Hoffmann,R.S. Höing, A. Junkes, R. Klanner, R. Kogler,T. Lapsien, T. Lenz, I. Marchesini, D. Marconi,

M. Meyer, D. Nowatschin, J. Ott, F. Pantaleo2,T. Peiffer, A. Perieanu, N. Pietsch,J. Poehlsen, D. Rathjens,

C. Sander, H. Schettler,P. Schleper, E. Schlieckau,A. Schmidt, J. Schwandt, M. Seidel,V. Sola, H. Stadie,

G. Steinbrück, H. Tholen, D. Troendle,E. Usai, L. Vanelderen, A. Vanhoefer, B. Vormwald

UniversityofHamburg,Hamburg,Germany

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

A. Dierlamm, S. Fink,F. Frensch, M. Giffels,A. Gilbert, F. Hartmann2,S.M. Heindl, U. Husemann,

I. Katkov6, A. Kornmayer2, P. Lobelle Pardo, B. Maier, H. Mildner, M.U. Mozer, T. Müller,Th. Müller,

M. Plagge, G. Quast, K. Rabbertz,S. Röcker, F. Roscher, H.J. Simonis,F.M. Stober,R. Ulrich,

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

InstitutfürExperimentelleKernphysik,Karlsruhe,Germany

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

I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

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

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

UniversityofIoánnina,Ioánnina,Greece

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

A.J. Zsigmond

WignerResearchCentreforPhysics,Budapest,Hungary

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

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

M. Bartók24,A. Makovec,P. Raics, Z.L. Trocsanyi, B. Ujvari

UniversityofDebrecen,Debrecen,Hungary

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

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

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

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

PanjabUniversity,Chandigarh,India

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

K. Ranjan,R. Sharma, V. Sharma

UniversityofDelhi,Delhi,India

S. Banerjee, S. Bhattacharya, K. Chatterjee,S. Dey,S. Dutta, Sa. Jain, N. Majumdar, A. Modak, K. Mondal,

S. Mukherjee,S. Mukhopadhyay, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar, M. Sharan

SahaInstituteofNuclearPhysics,Kolkata,India

A. Abdulsalam,R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty2,L.M. Pant, P. Shukla, A. Topkar

BhabhaAtomicResearchCentre,Mumbai,India

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

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

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

TataInstituteofFundamentalResearch,Mumbai,India

S. Chauhan,S. Dube, S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

H. Bakhshiansohi,H. Behnamian,S.M. Etesami28, A. Fahim29, R. Goldouzian, M. Khakzad,

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

M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, C. Calabriaa,b, C. Caputoa,b, A. Colaleoa,D. Creanzaa,c,L. Cristellaa,b,N. De Filippisa,c, M. De Palmaa,b, L. Fiorea, G. Iasellia,c, G. Maggia,c, M. Maggia,G. Minielloa,b,S. Mya,c,S. Nuzzoa,b,

A. Pompilia,b,G. Pugliesea,c,R. Radognaa,b,A. Ranieria,G. Selvaggia,b,L. Silvestrisa,2, R. Vendittia,b,

P. Verwilligena

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

G. Abbiendia,C. Battilanaa,2,A.C. Benvenutia, D. Bonacorsia,b, S. Braibant-Giacomellia,b, L. Brigliadoria,b, R. Campaninia,b, P. Capiluppia,b,A. Castroa,b,F.R. Cavalloa, S.S. Chhibraa,b,

G. Codispotia,b, M. Cuffiania,b,G.M. Dallavallea,F. Fabbria,A. Fanfania,b,D. Fasanellaa,b, P. Giacomellia, C. Grandia, L. Guiduccia,b,S. Marcellinia,G. Masettia, A. Montanaria,F.L. Navarriaa,b, A. Perrottaa, A.M. Rossia,b, T. Rovellia,b, G.P. Sirolia,b,N. Tosia,b, R. Travaglinia,b

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

G. Cappelloa,M. Chiorbolia,b,S. Costaa,b,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,S. Gonzia,b,V. Goria,b, P. Lenzia,b,M. Meschinia,S. Paolettia, G. Sguazzonia,A. Tropianoa,b,L. Viliania,b

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

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

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,M.E. Dinardoa,b_{, S. Fiorendi}a,b_{,S. Gennai}a_{,R. Gerosa}a,b_{,A. Ghezzi}a,b_{, P. Govoni}a,b_,

S. Malvezzia, R.A. Manzonia,b,B. Marzocchia,b,2,D. Menascea,L. Moronia, M. Paganonia,b,D. Pedrinia, S. Ragazzia,b, N. Redaellia,T. Tabarelli de Fatisa,b

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

S. Buontempoa, N. Cavalloa,c, S. Di Guidaa,d,2, M. Espositoa,b, F. Fabozzia,c,A.O.M. Iorioa,b,G. Lanzaa, L. Listaa,S. Meolaa,d,2,M. Merolaa,P. Paoluccia,2,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,2, N. Bacchettaa, L. Benatoa,b,D. Biselloa,b, A. Bolettia,b,R. Carlina,b,P. Checchiaa,

M. Dall’Ossoa,b,2,T. Dorigoa,U. Dossellia, F. Gasparinia,b, U. Gasparinia,b,F. Gonellaa,A. Gozzelinoa, S. Lacapraraa,M. Margonia,b,A.T. Meneguzzoa,b,M. Passaseoa,J. Pazzinia,b,M. Pegoraroa,

N. Pozzobona,b,P. Ronchesea,b, F. Simonettoa,b,E. Torassaa,M. Tosia,b,M. Zanettia,P. Zottoa,b, A. Zucchettaa,b,2,G. Zumerlea,b

a_{INFNSezionediPadova,Padova,Italy} b_{UniversitàdiPadova,Padova,Italy}

A. Braghieria,A. Magnania,P. Montagnaa,b_{, S.P. Ratti}a,b_{,V. Re}a_{, C. Riccardi}a,b_{, P. Salvini}a_{, I. Vai}a_,

P. Vituloa,b

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

L. Alunni Solestizia,b, M. Biasinia,b, G.M. Bileia,D. Ciangottinia,b,2,L. Fanòa,b, P. Laricciaa,b, G. Mantovania,b, M. Menichellia,A. Sahaa,A. Santocchiaa,b, A. Spieziaa,b

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

K. Androsova,31,P. Azzurria,G. Bagliesia,J. Bernardinia,T. Boccalia,G. Broccoloa,c,R. Castaldia, M.A. Cioccia,31,R. Dell’Orsoa, S. Donatoa,c,2,G. Fedi, L. Foàa,c,†,A. Giassia, M.T. Grippoa,31,

F. Ligabuea,c,T. Lomtadzea,L. Martinia,b, A. Messineoa,b, F. Pallaa,A. Rizzia,b,A. Savoy-Navarroa,32, A.T. Serbana, P. Spagnoloa,P. Squillaciotia,31, R. Tenchinia,G. Tonellia,b, A. Venturia, P.G. Verdinia

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

c_{ScuolaNormaleSuperiorediPisa,Pisa,Italy}

L. Baronea,b, F. Cavallaria,G. D’imperioa,b,2, D. Del Rea,b,M. Diemoza, S. Gellia,b,C. Jordaa,E. Longoa,b, F. Margarolia,b, P. Meridiania,G. Organtinia,b, R. Paramattia,F. Preiatoa,b, S. Rahatloua,b,C. Rovellia, F. Santanastasioa,b, P. Traczyka,b,2

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

N. Amapanea,b,R. Arcidiaconoa,c,2,S. Argiroa,b,M. Arneodoa,c,R. Bellana,b, C. Biinoa, N. Cartigliaa, M. Costaa,b,R. Covarellia,b, A. Deganoa,b, N. Demariaa,L. Fincoa,b,2, B. Kiania,b, C. Mariottia,

S. Masellia,E. Migliorea,b, V. Monacoa,b, E. Monteila,b, M. Musicha, M.M. Obertinoa,b,L. Pachera,b, N. Pastronea,M. Pelliccionia,G.L. Pinna Angionia,b, F. Raveraa,b,A. Romeroa,b, M. Ruspaa,c,R. Sacchia,b,

A. Solanoa,b,A. Staianoa, U. Tamponia

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

c_{UniversitàdelPiemonteOrientale,Novara,Italy}

S. Belfortea,V. Candelisea,b,2,M. Casarsaa, F. Cossuttia,G. Della Riccaa,b, B. Gobboa, C. La Licataa,b, M. Maronea,b, A. Schizzia,b, A. Zanettia

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

A. Kropivnitskaya,S.K. Nam

KangwonNationalUniversity,Chunchon,RepublicofKorea

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

KyungpookNationalUniversity,Daegu,RepublicofKorea

J.A. Brochero Cifuentes,H. Kim, T.J. Kim, M.S. Ryu

ChonbukNationalUniversity,Jeonju,RepublicofKorea

S. Song

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

S. Choi, Y. Go,D. Gyun, B. Hong,M. Jo, H. Kim,Y. Kim, B. Lee, K. Lee,K.S. Lee, S. Lee, S.K. Park,Y. Roh

KoreaUniversity,Seoul,RepublicofKorea

H.D. Yoo

SeoulNationalUniversity,Seoul,RepublicofKorea

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

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

SungkyunkwanUniversity,Suwon,RepublicofKorea

A. Juodagalvis,J. Vaitkus

VilniusUniversity,Vilnius,Lithuania

I. Ahmed,Z.A. Ibrahim, J.R. Komaragiri, M.A.B. Md Ali33,F. Mohamad Idris34,W.A.T. Wan Abdullah,

M.N. Yusli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

E. Casimiro Linares, H. Castilla-Valdez, E. De La Cruz-Burelo,I. Heredia-de La Cruz35,

A. Hernandez-Almada,R. Lopez-Fernandez, A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, F. Vazquez Valencia

UniversidadIberoamericana,MexicoCity,Mexico

I. Pedraza, H.A. Salazar Ibarguen

BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico

A. Morelos Pineda

UniversidadAutónomadeSanLuisPotosí,SanLuisPotosí,Mexico

D. Krofcheck

UniversityofAuckland,Auckland,NewZealand

P.H. Butler

UniversityofCanterbury,Christchurch,NewZealand

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

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

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

M. Walczak

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

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

N. Leonardo,L. Lloret Iglesias,F. Nguyen, 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,V. Konoplyanikov,

A. Lanev,A. Malakhov,V. Matveev36, P. Moisenz, V. Palichik,V. Perelygin, S. Shmatov, S. Shulha,

N. Skatchkov, V. Smirnov,A. Zarubin

V. Golovtsov,Y. Ivanov, V. Kim37,E. Kuznetsova, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov,

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

PetersburgNuclearPhysicsInstitute,Gatchina(St.Petersburg),Russia

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

A. Pashenkov,D. Tlisov, A. Toropin

InstituteforNuclearResearch,Moscow,Russia

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

A. Zhokin

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia

A. Bylinkin

NationalResearchNuclearUniversity’MoscowEngineeringPhysicsInstitute’(MEPhI),Moscow,Russia

V. Andreev,M. Azarkin38,I. Dremin38, M. Kirakosyan, A. Leonidov38,G. Mesyats, S.V. Rusakov,

A. Vinogradov

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Baskakov,A. Belyaev, E. Boos,A. Ershov, A. Gribushin, A. Kaminskiy39,O. Kodolova,V. Korotkikh,

I. Lokhtin,I. Myagkov, S. Obraztsov,S. Petrushanko,V. Savrin, A. Snigirev, I. Vardanyan

SkobeltsynInstituteofNuclearPhysics,LomonosovMoscowStateUniversity,Moscow,Russia

I. Azhgirey,I. Bayshev,S. Bitioukov, V. Kachanov, A. Kalinin, D. Konstantinov,V. Krychkine, V. Petrov,

R. Ryutin, A. Sobol,L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian,A. Volkov

StateResearchCenterofRussianFederation,InstituteforHighEnergyPhysics,Protvino,Russia

P. Adzic40,M. Ekmedzic, J. Milosevic,V. Rekovic

UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia

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

D. Domínguez Vázquez, 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

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

UniversidadAutónomadeMadrid,Madrid,Spain

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

J.M. Vizan Garcia

UniversidaddeOviedo,Oviedo,Spain

I.J. Cabrillo, A. Calderon, J.R. Castiñeiras De Saa, P. De Castro Manzano,J. Duarte Campderros,

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

F. Matorras,F.J. Munoz Sanchez, J. Piedra Gomez, T. Rodrigo, A.Y. Rodríguez-Marrero, A. Ruiz-Jimeno,

L. Scodellaro,I. Vila, R. Vilar Cortabitarte

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

L. Benhabib,J.F. Benitez, G.M. Berruti, P. Bloch,A. Bocci, A. Bonato,C. Botta, H. Breuker, T. Camporesi,

G. Cerminara, S. Colafranceschi41,M. D’Alfonso, D. d’Enterria, A. Dabrowski, V. Daponte, A. David,

M. De Gruttola, F. De Guio, A. De Roeck, S. De Visscher, E. Di Marco,M. Dobson, M. Dordevic, B. Dorney,

T. du Pree,M. Dünser, N. Dupont,A. Elliott-Peisert, G. Franzoni, W. Funk, D. Gigi,K. Gill, D. Giordano,

M. Girone, F. Glege, R. Guida,S. Gundacker, M. Guthoff, J. Hammer, P. Harris,J. Hegeman, V. Innocente,

P. Janot,H. Kirschenmann, M.J. Kortelainen, K. Kousouris,K. Krajczar,P. Lecoq,C. Lourenço,M.T. Lucchini,

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

S. Morovic, M. Mulders, M.V. Nemallapudi,H. Neugebauer, S. Orfanelli42,L. Orsini, L. Pape, E. Perez,

M. Peruzzi,A. Petrilli, G. Petrucciani, A. Pfeiffer,D. Piparo, A. Racz,G. Rolandi43,M. Rovere, M. Ruan,

H. Sakulin, C. Schäfer, C. Schwick,A. Sharma,P. Silva, M. Simon, P. Sphicas44, D. Spiga,J. Steggemann,

B. Stieger, M. Stoye,Y. Takahashi, D. Treille, A. Triossi, A. Tsirou,G.I. Veres22, N. Wardle, H.K. Wöhri,

A. Zagozdzinska45,W.D. Zeuner

CERN,EuropeanOrganizationforNuclearResearch,Geneva,Switzerland

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

D. Renker, T. Rohe

PaulScherrerInstitut,Villigen,Switzerland

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

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

P. Martinez Ruiz del Arbol, M. Masciovecchio, D. Meister,F. Micheli, P. Musella,F. Nessi-Tedaldi,

F. Pandolfi,J. Pata, F. Pauss, L. Perrozzi,M. Quittnat, M. Rossini,A. Starodumov46,M. Takahashi,

V.R. Tavolaro, K. Theofilatos, R. Wallny

InstituteforParticlePhysics,ETHZurich,Zurich,Switzerland

T.K. Aarrestad, C. Amsler47, L. Caminada,M.F. Canelli, V. Chiochia,A. De Cosa, C. Galloni, A. Hinzmann,

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

UniversitätZürich,Zurich,Switzerland

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

NationalCentralUniversity,Chung-Li,Taiwan

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

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

NationalTaiwanUniversity(NTU),Taipei,Taiwan

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

ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

A. Adiguzel, M.N. Bakirci48, Z.S. Demiroglu,C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut,

Y. Guler, E. Gurpinar,I. Hos, E.E. Kangal49, G. Onengut50,K. Ozdemir51, S. Ozturk48, A. Polatoz,

B. Tali52, M. Vergili,C. Zorbilmez

CukurovaUniversity,Adana,Turkey

I.V. Akin, B. Bilin,S. Bilmis, B. Isildak53,G. Karapinar54, M. Yalvac, M. Zeyrek

MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E.A. Albayrak55,E. Gülmez,M. Kaya56, O. Kaya57,T. Yetkin58

K. Cankocak,S. Sen59, F.I. Vardarlı

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, E. Clement, D. Cussans,H. Flacher, J. Goldstein,M. Grimes,

G.P. Heath, H.F. Heath,J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold60, S. Paramesvaran,A. Poll,

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

UniversityofBristol,Bristol,UnitedKingdom

A. Belyaev61, C. Brew, R.M. Brown, D. Cieri, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, E. Olaiya,

D. Petyt,C.H. Shepherd-Themistocleous, A. Thea, L. Thomas, I.R. Tomalin, T. Williams, W.J. Womersley,

S.D. Worm

RutherfordAppletonLaboratory,Didcot,UnitedKingdom

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

N. Cripps,P. Dauncey,G. Davies, A. De Wit, M. Della Negra,P. Dunne, A. Elwood, W. Ferguson, J. Fulcher,

D. Futyan,G. Hall, G. Iles, M. Kenzie,R. Lane, R. Lucas60, L. Lyons, A.-M. Magnan, S. Malik,J. Nash,

A. Nikitenko46,J. Pela, M. Pesaresi, K. Petridis,D.M. Raymond, A. Richards, A. Rose,C. Seez,A. Tapper,

K. Uchida, M. Vazquez Acosta62, T. Virdee,S.C. Zenz

ImperialCollege,London,UnitedKingdom

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

M. Turner

BrunelUniversity,Uxbridge,UnitedKingdom

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

BaylorUniversity,Waco,USA

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

TheUniversityofAlabama,Tuscaloosa,USA

A. Avetisyan, T. Bose,C. Fantasia, D. Gastler, P. Lawson, D. Rankin, C. Richardson, J. Rohlf, J. St. John,

L. Sulak,D. Zou

BostonUniversity,Boston,USA

J. Alimena,E. Berry, S. Bhattacharya, D. Cutts, N. Dhingra, A. Ferapontov,A. Garabedian, J. Hakala,

U. Heintz, E. Laird,G. Landsberg, Z. Mao, M. Narain, S. Piperov,S. Sagir, T. Sinthuprasith, R. Syarif

BrownUniversity,Providence,USA

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

P.T. Cox,R. Erbacher, M. Gardner, W. Ko, R. Lander, M. Mulhearn, D. Pellett, J. Pilot, F. Ricci-Tam,

S. Shalhout, J. Smith, M. Squires, D. Stolp, M. Tripathi,S. Wilbur, R. Yohay

UniversityofCalifornia,Davis,Davis,USA

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