Search for resonant pair production of Higgs bosons decaying to two bottom quark-antiquark pairs in proton-proton collisions at 8 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Experiments Letter

Search

for

resonant

pair

production

of

Higgs

bosons

decaying

to

two

bottom

quark–antiquark

pairs

in

proton–proton

collisions

at

8 TeV

.CMSCollaboration⋆ CERN,Switzerland

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

Received13March2015

Receivedinrevisedform18August2015 Accepted19August2015

Availableonline24August2015 Editor: M.Doser Keywords: CMS Higgs di-Higgs Radion KKgraviton RS1

Amodel-independentsearchforanarrowresonanceproducedinproton–protoncollisionsat√s=8 TeV anddecayingtoapairof125 GeVHiggsbosonsthatinturneachdecaysintoabottomquark–antiquark pairis performedbytheCMS experiment atthe LHC. Theanalyzed datacorrespondto anintegrated luminosity of 17.9 fb−1_{.Noevidencefor asignal isobserved.Upper limits ata95%confidence level}

on theproduction crosssectionfor sucharesonance, inthe massrangefrom 270to 1100 GeV,are reported. Usingtheseresults,aradionwithdecayconstantof1 TeVandmassfrom300to1100 GeV, andaKaluza–Kleingravitonwithmassfrom380to830 GeVareexcludedata95%confidencelevel.

©2015CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.Thisisanopenaccess articleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Following the discovery of a Higgs boson (H) at the CERN LHC[1–3],withmassaround 125 GeVandpropertiesso far con-sistent with the standard model (SM) of particle physics, it has become important to search fornew resonances that decayinto pairsofsuchHiggsbosons.Whilenon-resonantpairproductionof theHiggs bosonis allowed inthe SM,the theoretical production crosssectionisapproximately10 fb[4]andwellbeyondthe sen-sitivityofcurrentlyacquireddata.However,severalwell-motivated hypotheses of physics beyondthe standard model posit narrow-widthresonancesthatdecayintopairsofHiggsbosons,andcould be producedwithlarge enough crosssections tobe probed with existing data. The radion [5] andKaluza–Klein (KK) gravitons in theRandall–Sundrum(RS1)[6]modelofwarpedextradimensions areexamplesofsuchresonances[7].

This letter reports the results of a model-independent search forthe resonant pair productionof Higgs bosons. The search for the narrow widthresonance, denoted by X, is performed inthe 270–1100 GeVmass range.Datafromproton–protoncollisions at theLHCandrecordedbytheCMSexperimentcorrespondingtoan

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

integratedluminosityof17.9±0.5 fb−1_at√_{s=8 TeV isused.We}

perform thissearch forthe casewhere bothHiggs bosons decay intobottomquark–antiquarkpairs(bb)[8].Themainchallengeof thissearchistodistinguishthesignaloffourbottomquarksinthe final state thathadronize intojets(bjets)fromthecopious mul-tijetbackgrounddescribedbyquantumchromodynamics(QCD)in pp collisions.Weaddressthischallengebysuitableeventselection criteriathatincludededicatedb-jetidentificationtechniquesanda modelofthemultijetbackgroundthatisvalidatedindatacontrol regions.Ourresultsmaybecomparedwithasearchperformedby theATLASexperiment[9]thatalsoprobesthephysicsofresonant Higgsbosonpairproduction,albeitinthechannelwhereoneHiggs bosondecaystobottomquarksandtheotherdecaystophotons. 2. Detectorandeventreconstruction

AdetaileddescriptionoftheCMSdetector,togetherwitha de-scriptionofthecoordinatesystemusedandtherelevantkinematic variables,canbefoundinRef.[10].ThecentralfeatureoftheCMS apparatusisasuperconducting solenoidof6 m internaldiameter thatgeneratesanaxialmagneticfieldof3.8 T.Withinthesolenoid volumeare asiliconpixelandstriptracker,aleadtungstate crys-talelectromagneticcalorimeter,andabrassandscintillatorhadron calorimeter.Muonsaredetectedandtheirpropertiesmeasuredin

http://dx.doi.org/10.1016/j.physletb.2015.08.047

0370-2693/©2015CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

gas-ionizationdetectorsembeddedinasteelflux-returnyoke out-sidethesolenoid. Jetsare reconstructedusingtheanti-kT

cluster-ingalgorithm[11,12]withadistanceparameterof0.5appliedon thecollectionofparticlecandidatesreconstructedbythe particle-flow (PF) algorithm [13,14]. The PF algorithm reconstructs and identifieseach individualparticlewitha combinationof informa-tionfromthevariouselementsoftheCMSdetector.Tomitigatethe effectof additionalparticles that donot originate fromthe hard interactioninjetreconstruction,wesubtractchargedhadronsthat donotarise fromtheprimaryvertexassociatedwiththejet from thecollectionofclusteredparticles.Further,anaverageneutral en-ergydensityfromparticlesnotarising fromtheprimary vertexis evaluatedandsubtractedfromthejets[15].Energycorrectionsfor thejetsaredeterminedasfunctionsofthejettransverse momen-tum pT and pseudorapidity |η|. Jet identification criteria[16] to

rejectdetectornoisemisidentified asjets,andjetsnotoriginating fromthehardinteractionarealsoapplied.

Inorder toidentify (tag) bjets, we rely on thefact that bot-tom quarks hadronize into b hadrons which have decay lengths oftheorderofcτ=450 µm.Thus,their decayproducts originate fromsecondaryverticesmadeoftracksthathaveimpact parame-terswithrespecttotheprimaryvertexofasimilarscale.Thepixel trackerprovides an impact parameter resolution ofabout15 µm forchargedtrackswith|η|<2.4.Tomaximize theb-tagging per-formanceofthedetector,wecombinetheoutputdiscriminantsof severalb-taggingalgorithms described inRef.[17] withatrained artificialneural network. Thiswe call the combined multivariate (CMVA) algorithm. In particular, we combine the outputs of the combinedsecondaryvertex(CSV)taggerthat usessecondary ver-ticesidentifiedbytheinclusivevertexfinder(IVF)algorithm[18], thejetprobability(JP)tagger,andthetwosoftleptontaggers.

Thefirst level of thetrigger, consisting ofcustomized proces-sors, collects data for this analysis using information from the calorimetersandrequires twojetsto exceed pT thresholds of56

or64 GeV,depending onluminosity conditions.Thesecond level ofthetrigger,consistingofsoftwarealgorithmsexecutedonafarm ofcommercialprocessors,usesinformationfromtheentire detec-tortoreconstructPFjets, andrequiresfourPFjetswith|η|<2.4 andpT>30 GeV,ofwhichtwojetsmusthave pT>80 GeV. Fur-ther,to record signal eventsand reject backgroundQCD multijet events,two jetsare required to be tagged by the CSV b-tagging algorithmimplementedatthetrigger.

3. Simulatedsamples

Tomodeltheproductionofagenericnarrow-widthspin-0 res-onance,we use aMonte Carlosimulationof theRS1radion pro-ducedthroughgluon fusion.Theangulardistributions ofa spin-2 resonanceare distinct from those ofa spin-0 resonance, and re-sult in different kinematic distributions. Therefore, we evaluate the signal efficiencies for a narrow-width spin-2 resonancefrom a separate simulation of the first excitation of the KK graviton producedthrough gluonfusion inthesame extradimension sce-narioastheradion. Theresonanceis forcedto decaytoapairof Higgs bosons where both Higgs bosons decay to bb. Samples of thesesignal events, aswell as background events fromdiboson, W+jets,Z+jets andtop-quarkpairproduction(tt)processes,are generatedusing the MadGraph 5.1 [19] program interfaced with pythia 6.4[20]forpartonshoweringandhadronization.QCD mul-tijet event samples are simulated with the pythia 6.4 program. A sample of events where the Higgs boson is produced in as-sociation with a Z boson is simulated using the powheg event generator[21–23]interfacedwiththe herwig++ [24]program for showering andhadronization. We set the pythia 6.4 parameters

fortheunderlyingeventtotheZ2*tune[25].Theresponseofthe CMSdetectorismodeledusing Geant4[26].

Onaverage,21pp interactions occurredper bunchcrossing in thedatausedinthisanalysis.Additionalsimulatedpp interactions overlappingwiththeeventofinterestwereaddedtothesimulated samples to reproduce the distribution of the numberof primary verticespereventreconstructedindata.

4. Eventselection

The trigger-level jet pT thresholds confine our search for

a narrow-width X _→HH→bbb¯ b resonance¯ to masses above 270 GeV. Beyond mX ≈800 GeV, the selection efficiency is in-creasingly limited by the merging of jets from the same Higgs boson,andwecurtailthissearchat1100 GeV.Thekinematic dis-tributions ofthedecayproductsvarysubstantially overthismass range.Therefore,tooptimizethesearchsensitivity,we use differ-ent event selection criteriain three main kinematic regions: the low-massregion(LMR)formasshypothesesfrom270to450 GeV, themedium-massregion(MMR)formassesfrom450to730 GeV, andthehigh-massregion(HMR)formassesfrom730to1100 GeV. Eventselectionbeginswiththeidentificationofevents contain-ingatleastfourjetsinthecentralregionofthedetector(|η|<2.4) thatareb-taggedandhavepT>40 GeV.Tob-tagajet,werequire ittopassaworkingpointfortheCMVAalgorithmthatmaximizes thesensitivityofthissearch.Forjetswith pT>40 GeV and|η|< 2.4 thisworkingpointyieldsa75%efficiencyfortaggingjets orig-inatingfrombhadronsandamistaggingrateof3%forlight-flavor jets.FortheLMR,wecombinethesebjetsintopairstocreateHH candidatessuchthat|mH−125 GeV|<35 GeV foreachcandidate Higgsboson.Themassresolutionon theHiggsbosonintheLMR is found to be approximately 9 GeV. Selected HHcandidates are requiredtohaveatleasttwojetswith pT>90 GeV.IntheMMR, signal eventshave largeLorentz factors forthe Higgsboson can-didates. Therefore,HH candidates for thisregion are constructed fromfourjetssuchthatthe $R=!$η2+ $φ2 _{betweenthejets}

associatedwithanHcandidateremainwithin1.5,where$ηand $φ are thedifferencesinthepseudorapiditiesandazimuthal an-glesofthetwo jets. FortheHMR, weusethe samecriteriaused inthe MMRwithan additional requirementof pT>300 GeV on one ofthe Hcandidatestobetterdiscriminatesignal eventsfrom background.Inallthreeregions,incaseofmultipleHHcandidates in an event, the combination with the smallest |mH1−mH2| is

chosen.HavingidentifiedthetwoHiggsbosoncandidatesineach event, weplottheir masses, mH1 andmH2,onatwo-dimensional

histogram asshown in Fig. 1. H1 and H2 are chosen atrandom

from the two reconstructed H candidates. As the final selection criterion applied in each of the three mass hypothesis regions, we requireeventstofall within thesignal region(SR)definedas "

$m2_H1+ $m2_H2<17.5 GeV,where$mH1,2=mH1,2−125 GeV.

Theefficienciesoftheseselectioncriteriaforspin-0andspin-2 resonances at representative masses are shown in Table 1. The major loss in efficiency for all mass hypotheses comes from the b-taggingrequirementfor4jets. Forthe300 GeVmass hypothe-sis,thisiscompoundedbythetriggerinefficiency.Thedistribution oftheaforementioned$RbetweenjetsfromasingleHiggsboson isnarrowerforthespin-2resonance,andthusrequiring$R<1.5 resultsinahigherefficiencyforit.

5. Signalmodeling

For signal events, the aforementioned event selection criteria areexpectedtoproduceasharppeakinthemX distributionover a relatively featureless background from events arising from SM

Fig. 1. IllustrationoftheSR,SB,VRandVSkinematicregionsinthe(mH1,mH2) planeusedtomotivateand validatethe parametricmodelfor theQCD multijet background.ThequantitiesmH1 andmH2 arethe tworeconstructedHiggsboson masses.Thedistributionindataeventsafterb-taggingandkinematicselectionsis shownwiththeSRblinded.

Table 1

Efficienciesoftheeventselectioncriteriaforgenericspin-0andspin-2resonances decayingtoapairofHiggsbosonsinthefourbjetfinalstateatrepresentative masses.

Selection eff. (%) Mass (GeV)

300 500 700 900 1100

spin-0 0.05 2.3 4.9 4.6 2.2

spin-2 0.09 3.4 6.6 5.4 2.3

processes.TheinterferencebetweenSMbackgroundprocessesand thenarrowresonantsignalisexpectedtobenegligible.Tosearch forsignal events atvarious mass hypotheses, we fitthe mX dis-tribution indata eventsin the SRto a parametric modelforthe signal peak on top ofparametric models appropriate for compo-nents oftheSMbackground.Thisprocedure isperformedforthe LMR,theMMR,andtheHMRseparately.

To improve the mass resolution of the signal X_→HH reso-nance, we perform a fit that constrains the invariant masses of theHiggsbosoncandidates.Inthefit,themomentaofthe recon-structed bjets are allowed to floatwithin their expected resolu-tions.SincetheuncertaintyinthereconstructedmassoftheHiggs bosoncandidateduetothemeasurementofjetdirectionissmaller than that dueto the measurement of jet energy, this constraint mainlyaffectsthelatter.Thisfitimprovestheinvariantmass reso-lutionofthereconstructedsignalresonanceby20–40%,depending onthemasshypothesis.Extensive testsinbackground-dominated controlregionsindatashowthatnoartificialstructuresare intro-ducedinthebackgroundmassdistributionsbythisprocedure.

Webuildtheparametricmodelforeachsignalmasshypothesis byfittingtheshapeofthemX distributionofsimulatedeventsthat areacceptedbytheselectioncriteriaandcorrectedfordifferences betweendataandsimulation.AsumoftwoGaussianfunctions, re-quiringfiveparameters,isusedfortheLMRfittoaccountfortails inthedistributionfromincorrectcombinationsofjets.IntheMMR andtheHMR,wefitafunctionwithaGaussiancoresmoothly ex-tendedonbothsidestoexponentialtails,suchthatthefunctionis continuous both inits value andits firstderivative. Thisrequires two parameters for the mean and width of the Gaussian

func-Fig. 2. AmaximumlikelihoodfittothemX distributionofsimulatedsignalevents for the 700 GeV mass hypothesis.The distributionis fittedto aGaussian core smoothlyextendedonbothsidestoexponentialtails.Herenisthenumberof de-greesoffreedominthefit.

tion, andtwo other parameters for theexponential tails on both sides. Anexample ofaparametricmodelforthe MMRsignal ob-tainedthroughthisprocedureisshowninFig. 2.Whilethemodel is constructed for the mass hypothesis of 700 GeV, its Gaussian corepeaksat714 GeVandhasawidthof21 GeV.Thismassshift isfoundtobelinearinmX andoccursduetotheaforementioned constraintofjetmomentatomH.

6. Backgroundmodeling

While the composition of background events in the SR is expected to be dominated by QCD multijet processes, we find through simulation that tt production contributes approximately 22%, 27%, and24%in theLMR, MMR,andHMR, respectively. We alsofindthatZ+jets,ZZ,andZHprocessescontributelessthan1% ofthebackgroundandthereforeneglecttheminthisanalysis.The

mX distributionofthesett eventsisfoundtobesomewhat differ-ent inshape fromthat ofQCD multijet events,andthereforewe treat it asa distinct component ofthe background andmodel it withaparametricform. Weobtainthisparametricformbyfitting the shapeof themX distribution ofsimulatedtt events accepted by theeventselectioncriteriato afunctionwitha Gaussiancore smoothly extended to an exponential tail on the high side. This function, henceforth referred toasGaussExp, iscontinuous in its value andits firstderivative. Ithastwo parameters forthemean andwidthoftheGaussianfunctionandoneparameterforthe de-cayconstantoftheexponentialtail.Thismodelisnormalizedtoa tt crosssectionof234 pb[27],andisallowedtofloatwitha sys-tematicuncertaintyof15%inthefinalfittoaccountfortheoretical and measurement uncertainties in our kinematically boosted re-gion.

WeusetheGaussExpparametricmodeltofitthemX distribu-tionoftheQCD multijetcomponentofthebackgroundintheSR. WiththeSRkeptblinded,wemotivateandvalidate thischoiceof parametricmodelbythefactthatitfitswell theshapeofthemX QCD multijetbackgrounddistributions inseveraldifferentregions of the (mH1,mH2) plane depicted inFig. 1 anddescribed below.

Fig. 3. ThemXdistributionsindata(afterthett backgroundhasbeensubtracted)intheSBoftheMMR(topleft),theCRoftheMMR(topright),theVSoftheLMR(bottom left),andtheVRoftheLMR(bottomright).ThedistributionsarefittedtotheGaussExpparametricmodel.Theshadedregionscorrespondto±1σ variationsofthisfit. Herenisthenumberofdegreesoffreedomineachfit.Thepull,foragivenbin,isdefinedasthenumberofdataeventsminusthevalueofthefitmodel,dividedbythe uncertaintyinthenumberofdataevents.

Wedonot aimtopredict theparameters ofthemodelintheSR fromthe otherregions. Thesefits areperformedfortheLMR be-tween260and650 GeV,fortheMMRbetween400and900 GeV, andfortheHMR between600and1200 GeV.Ineachcasethett contribution,asexpectedfromsimulation,issubtracted.

We define a sideband region (SB) to the SR as 17.5 GeV < "

$m2_H1+ $m2_H2<35 GeV and$mH1$mH2<0.Foreventsinthis

region,the mX distribution isexpected tobe kinematically simi-lartothatforeventsintheSR,sinceineachofthesidebandsone

ofthereconstructedHiggsbosonmassesisslightlyhigherinvalue than forevents intheSRwhilethe other isslightlylower.Asan example,Fig. 3topleft showsthefitperformedforeventsinthe SBpassingtheHMR selection.Anothersetofeventsthatpassthe kinematicrequirementsoftheeventselectioncriteriaintheSR re-gionofthe(mH1,mH2)planebutrequiredtohaveoneofthefour

jetsnotbeb-taggedisselectedtofurthertesttheapplicability of theGaussExpmodelindescribingthemX distributionoftheQCD multijetbackgroundinadifferentbutkinematicallysimilarregion.

Fig. 4. ThemX distributionindataintheSRbetween260and650 GeVoftheLMR(topleft),between400and900 GeV ofthe MMR(topright),and between600 and1200 GeVintheHMR(bottom).Alldistributionsarefittedtothebackground-onlyhypothesisforillustration,showingtherelativecontributionsoftheQCDmultijet (dashed–dottedred)andtt (dashedgreen)processes.Thepull,foragivenbin,isdefinedasthenumberofdataeventsminusthevalueofthebackground-onlyfit,divided bytheuncertaintyinthenumberofdataevents.Alsoforillustration,weoverlaythesignalmodelsofthespin-0resonance(dottedblue)correspondingtomasshypotheses andproductioncrosssectionsof350 GeVand653 fbfortheLMR,700 GeVand17.6 fbfortheMMR,and900 GeVand8.1 fbfortheHMR.Thesecrosssectionscorrespond totheobservedupperlimits,whicharecomputedforsignalmasshypothesesfrom270to450 GeVintheLMR,from450to730 GeVintheMMR,andfrom730to1100 GeV intheHMR.(Forinterpretationofthereferencestocolorinthisfigurelegend,thereaderisreferredtothewebversionofthisarticle.)

Table 2

Relativesystematicuncertaintiesintheselectionefficienciesforsignalandtt eventsintheLMR,theMMR,andtheHMR. Sourceofsystematic

uncertainty

Impact in LMR (%) Impact in MMR (%) Impact in HMR (%)

Signal t¯t Signal t¯t Signal t¯t

Jet energy scale 0.1–0.2 0.8 0.0–0.2 0.1 0.1–0.3 1.9

Jet energy resolution 2.4–7.0 2.7 5.5–7.0 2.2 4.9–5.3 7.2

b-tagging scale factor 12.7 12.7 12.7 12.7 12.7 12.7

Trigger scale factor 6.0–18.8 9.1 6.1–8.0 7.2 7.4–7.9 7.2

Thisis calledthe data Control Region(CR), andthe fit for these events,that would have otherwise passed the HMR selection, is alsoshowninFig. 3onthetop-right.Inbothcases,thegoodness ofthefit,characterizedbythe χ2 _{perdegreeoffreedom,isfound}

tobereasonable.

These two cases already lend significant confidence to the choice of the GaussExp parametric model for the SR. However, wecarryoutfurtherchecksinneighboringvalidationregions(VR) witha corresponding sideband (VS) that are definedsimilarly to theSR andSBregions but withmH1=mH2 centered atdifferent

values.ThegoodfitsforthemX distributionsintheseregionsnot onlydemonstrate theapplicability ofthe GaussExp modelto de-scribe these kinematically distinct QCD multijet events, but also that events in the VR are in fact kinematically similar to those intheVS. Asexamples, Fig. 3bottom-left andbottom-rightplots show the results of these fits for the LMR selection for the VS andthe VR, respectively, both centered atmH1=mH2=90 GeV.

We obtain similar results for the VR centered at mH1 =mH2 =

107.5,142.5and 160 GeV.

WhiletheGaussExpfunctionfitswellthemX distributionfrom QCDmultijeteventsinallthesedistinctregionsandthereforecan be expectedto be a good approximation ofthe parametric form ofthetrueparent distributionforeventsin theSR, other similar parametricmodelscouldbechoseninstead.Therefore,asystematic uncertaintyassociatedwiththechoiceofthisparametricmodelis evaluated by assuming a 7th order Bernstein polynomial, which alsofitsthemX distributionwellintheSB,tobethetrue distribu-tion.Pseudo-datasets aregeneratedfromthispolynomialfunction andfittedwiththeGaussExpfunctionaswellasotherpolynomial functionsto compute biasesin thereconstructed signal strength. Thisprocedure is performedforeach masshypothesis. These bi-ases are found to be of the order of 100 fb for the LMR, 10 fb fortheMMR,and20 fbfortheHMR.Weaccountforthisbiasas a signal-shaped systematicuncertainty in the background model with normalizationcentered at zero and a Gaussian uncertainty withstandarddeviationequaltothebias.

7.Systematicuncertainties

Sourcesofsystematicuncertaintiesthataffecttheselection effi-cienciesforsignalandtt eventsarelistedinTable 2anddescribed below.We varythe jet energy scale [28] by its uncertainty asa functionofjet pT and ηandfindthat thisaffectssignal

efficien-cies by a relative factor of up to 0.2% and tt efficiencies by up to 0.8%. We evaluate the effect of uncertainty in the jet energy resolutionby varying the jetenergies according tothe measured uncertainty.Thisisfoundtoaffectsignalefficienciesby2–7%,and tt efficienciesby2–3%.Theseuncertaintiesaffectnotonlythe nor-malizationsbut alsothe parameters of the signal andtt models, andaretakenintoaccountasnuisanceparametersinthefinalfit.

The trigger efficiencies for signal and tt events are evaluated approximatelyby passinggeneratedeventsthroughatrigger sim-ulation.Wethencorrecttheseefficienciesfordifferencesbetween simulationanddatabycomputingthedifference ina tt-enriched control regionobtained usinga trigger that requiresatleast one muonwithpT>24 GeV.Further,eventselectioncriteriarequiring

atleastonemuon withpT>40 GeV andatleastfourjetsinthe central regionofthe detectorwith pT>40 GeV areapplied.The data-to-simulationcorrectionfactorischaracterizedbythepTand

CMVAdiscriminants oftherelevantjets. Uncertaintiesinthis fac-torimpactsignalefficienciesby6–18%,andtt efficienciesby7–9%. Theb-taggingefficienciesoftheCMVAalgorithmforsignaland tt eventsarealsoevaluatedapproximatelythroughsimulationand then corrected by a data-to-simulation comparison. The compar-ison is performed in the same tt-enriched control region as the calculation of the trigger efficiency. The correction factor for the b-taggingefficiencies is consistent withunity. The uncertainty in thisfactorforfourbjetsisevaluatedtobe12.7%.

Additionally, theyields ofsignaleventsfora givenproduction crosssectionandtt eventsarebothaffectedbya2.6%uncertainty inthemeasurementoftheintegratedluminosity[29].

8. Results

The mX distribution that we observe in data within the SR, along witha binned maximum-likelihoodfit withthe aforemen-tioned parametric background models, are shown in Fig. 4. We computetheobservedandexpectedupperlimitsonthecross sec-tion for pp→X_→HH→bbb¯ b at¯ a 95% confidence level (CL) using the modified frequentist CLS method [30,31] by fitting the

datawiththeparametricsignal,tt,andQCDmultijetmodels.This isdone separately inthedisjointranges ofmX fortheindividual regions described in Section 4, and the limits are presented to-gether inFig. 5. Theselimitsare shownforthespin-0 resonance inthetop plot,andthespin-2resonanceinthebottom plot.The green (dark) and yellow(light) bands respectively represent the 1σ and2σ confidence intervalsaround the expectedlimits. The observedupperlimitslie within2σ oftheexpectedupperlimits, andthus we concludethat there isno significant deviationfrom thebackground-onlyhypothesis.

The theoretical cross section forthe production via gluon fu-sion of a radion that decays to a pair ofHiggs bosons [32] that each in turn decays to a bb pair with a branching fraction of 58%[33]iscalculatedusing MadGraph 5.1[34]andsuperimposed on the experimental cross section limit for the spin-0 resonance in the plot on the left. In this calculation, the correction factor used to account for next-to-leading-order effects for electroweak couplings [35] and next-to-next-to-leading-order effects for QCD couplings [36] is identical to that used for Higgs boson produc-tion through gluon fusion. The warpedextra dimension scenario for thisradion hasthe product ofthe curvature, k, and halfthe circumference ofthe extra dimension, L, set to 35,a radion de-cay constant of (R=1 TeV, and no radion-Higgs boson mixing. The theoreticalcrosssection forthe radionhasanuncertainty of approximately15% that isnot usedto compute theexperimental limitsonspin-0resonanceproductionshowninFig. 5.Massesfor theradionbetween300and1100 GeVareexcluded ata95% CL. Asimilarlycalculatedtheoretical crosssectionfortheKKgraviton astheresonanceX,inthesamewarpedextradimensionscenario, isoverlaidonthelimitforthespin-2resonanceintheplotatthe bottom.Massesforsuch a graviton areexcluded ata 95% CL be-tween380and830 GeV.

Fig. 5. Theobservedandexpectedupperlimitsonthecrosssectionforpp→X→

HH→bbb¯ b at¯ a95%confidencelevel,wheretheresonanceXhasspin-0(top)and spin-2(bottom).ThetheoreticalcrosssectionfortheRS1radion,with(R=1 TeV,

kL₌35,andnoradion-Higgsbosonmixing,decayingtofourbjetsviaHiggsbosons isoverlaidonthetopplot.Thetheoreticalcrosssectionforthefirstexcitationof theKK-gravitonforthesameparametersisoverlaidonthebottomplot.

9. Summary

We have presented a model-independent search by the CMS experimentattheLHCforanarrowresonanceproducedinproton– protoncollisionsat√s=8 TeV anddecayingtoapairof125 GeV Higgs bosons that in turn each decays into a bottom quark– antiquarkpair.The analyzeddatacorrespond toan integrated lu-minosityof17.9 fb−1_{.Noevidenceforasignalisobserved.Upper}

limitsata95%CLontheproductioncrosssectionforsuchspin-0 andspin-2resonances,inthe massrangefrom270to1100 GeV, are reported. Using these results, a radion with decay constant of 1 TeV and mass from 300 to 1100 GeV, and a Kaluza–Klein graviton with massfrom 380 to 830 GeV are excluded at a 95% confidencelevel.

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,wegratefullyacknowledgethecomputingcentersand 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,andNSFC(China);COLCIENCIAS (Colombia);MSESandCSF(Croatia);RPF(Cyprus);MoER,ERCIUT andERDF(Estonia); AcademyofFinland,MEC,andHIP (Finland); CEA andCNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE andUM (Malaysia); CINVESTAV, CONACYT,SEP,andUASLP-FAI(Mexico);MBIE(NewZealand);PAEC (Pakistan);MSHEandNSC(Poland);FCT(Portugal);JINR(Dubna); MON,RosAtom,RASandRFBR(Russia);MESTD(Serbia);SEIDIand CPAN(Spain);SwissFundingAgencies(Switzerland);MST(Taipei); ThEPCenter,IPST, STARandNSTDA(Thailand);TUBITAK andTAEK (Turkey);NASU andSFFR (Ukraine);STFC(United Kingdom);DOE andNSF(USA).

Individuals have received support from the Marie-Curie pro-gram and the European Research Council and EPLANET (Euro-pean Union); the Leventis Foundation; the Alfred P. Sloan Foun-dation;theAlexandervonHumboldtFoundation;theBelgian 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 PLUS program of the Foundation for Polish Science, cofinanced from European Union, Regional Development Fund; theCompagniadi SanPaolo (Torino);the Consorzioper la Fisica (Trieste); MIURproject20108T4XTM (Italy); theThalisand Aristeiaprograms cofinancedbyEU-ESFandtheGreek NSRF;and the National Priorities Research Program by Qatar National Re-searchFund.

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CMSCollaboration

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

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, T. Bergauer, M. Dragicevic,J. Erö,M. Friedl, R. Frühwirth1_{,V.M. Ghete, C. Hartl, N. Hörmann,}

J. Hrubec, M. Jeitler1,W. Kiesenhofer, V. Knünz,M. Krammer1, I. Krätschmer,D. Liko, I. Mikulec,

D. Rabady2,B. Rahbaran, H. Rohringer, 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, S. Bansal,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

F. Blekman,S. Blyweert, J. D’Hondt,N. Daci, N. Heracleous, J. Keaveney,S. Lowette, M. Maes,A. Olbrechts,

Q. Python, D. Strom, S. Tavernier,W. Van Doninck, P. Van Mulders, G.P. Van Onsem,I. Villella

C. Caillol, B. Clerbaux, G. De Lentdecker, D. Dobur, L. Favart, A.P.R. Gay, A. Grebenyuk,A. Léonard,

A. Mohammadi, L. Perniè2, A. Randle-conde,T. Reis,T. Seva, L. Thomas, C. Vander Velde, P. Vanlaer,

J. Wang, F. Zenoni

UniversitéLibredeBruxelles,Bruxelles,Belgium

V. Adler,K. Beernaert, L. Benucci, A. Cimmino,S. Costantini, S. Crucy, A. Fagot,G. Garcia, J. Mccartin,

A.A. Ocampo Rios, D. Poyraz,D. Ryckbosch, S. Salva Diblen, M. Sigamani,N. Strobbe, F. Thyssen,

M. Tytgat, E. Yazgan, N. Zaganidis

GhentUniversity,Ghent,Belgium

S. Basegmez, C. Beluffi3,G. Bruno,R. Castello, A. Caudron, L. Ceard, G.G. Da Silveira, C. Delaere,

T. du Pree,D. Favart, L. Forthomme,A. Giammanco4_{,J. Hollar, A. Jafari, P. Jez,M. Komm, V. Lemaitre,}

C. Nuttens, D. Pagano,L. Perrini, A. Pin, K. Piotrzkowski, A. Popov5, L. Quertenmont,M. Selvaggi,

M. Vidal Marono, J.M. Vizan Garcia

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

N. Beliy, T. Caebergs,E. Daubie, G.H. Hammad

UniversitédeMons,Mons,Belgium

W.L. Aldá Júnior, G.A. Alves,L. Brito, M. Correa Martins Junior,T. Dos Reis Martins, J. Molina,

C. Mora Herrera,M.E. Pol, P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

W. Carvalho,J. Chinellato6,A. Custódio, E.M. Da Costa, D. De Jesus Damiao, C. De Oliveira Martins,

S. Fonseca De Souza, H. Malbouisson, D. Matos Figueiredo,L. Mundim, H. Nogima,W.L. Prado Da Silva,

J. Santaolalla, A. Santoro,A. Sznajder, E.J. Tonelli Manganote6_{,A. Vilela Pereira}

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

C.A. Bernardesb_{, S. Dogra}a_{,T.R. Fernandez Perez Tomei}a_{,E.M. Gregores}b_{, P.G. Mercadante}b_,

S.F. Novaesa, Sandra S. Padulaa

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

A. Aleksandrov, V. Genchev2,R. Hadjiiska, P. Iaydjiev,A. Marinov, S. Piperov, M. Rodozov,S. Stoykova,

G. Sultanov,M. Vutova

InstituteforNuclearResearchandNuclearEnergy,Sofia,Bulgaria

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

UniversityofSofia,Sofia,Bulgaria

J.G. Bian, G.M. Chen,H.S. Chen, M. Chen, T. Cheng, R. Du,C.H. Jiang, R. Plestina7,F. Romeo,J. Tao,

Z. Wang

InstituteofHighEnergyPhysics,Beijing,China

C. Asawatangtrakuldee, Y. Ban, S. Liu,Y. Mao, S.J. Qian, D. Wang,Z. Xu, L. Zhang,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

N. Godinovic, D. Lelas,D. Polic, I. Puljak

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic,M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,K. Kadija, J. Luetic,D. Mekterovic, 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. Finger,M. Finger Jr.8

CharlesUniversity,Prague,CzechRepublic

Y. Assran9,A. Ellithi Kamel10,M.A. Mahmoud11,A. Radi12,13

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

M. Kadastik, M. Murumaa, M. Raidal, A. Tiko

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Härkönen,V. Karimäki, R. Kinnunen, M.J. Kortelainen, 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,J. Malcles,J. Rander, A. Rosowsky,

M. Titov

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

S. Baffioni,F. Beaudette, P. Busson, E. Chapon,C. Charlot, T. Dahms, M. Dalchenko,L. Dobrzynski,

N. Filipovic,A. Florent, R. Granier de Cassagnac, L. Mastrolorenzo, P. Miné, I.N. Naranjo,M. Nguyen,

C. Ochando, G. Ortona,P. Paganini, S. Regnard, R. Salerno,J.B. Sauvan, Y. Sirois,C. Veelken, Y. Yilmaz,

A. Zabi

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

J.-L. Agram14,J. Andrea, A. Aubin,D. Bloch, J.-M. Brom,E.C. Chabert, C. Collard,E. Conte14,

J.-C. Fontaine14,D. Gelé, U. Goerlach,C. Goetzmann, 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,N. Beaupere, C. Bernet7, G. Boudoul2,E. Bouvier, S. Brochet, C.A. Carrillo Montoya,

M. Gouzevitch, B. Ille, T. Kurca, 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

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

Z. Tsamalaidze8

InstituteofHighEnergyPhysicsandInformatization,TbilisiStateUniversity,Tbilisi,Georgia

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

A. Ostapchuk, M. Preuten,F. Raupach, J. Sammet, S. Schael, J.F. Schulte, H. Weber, B. Wittmer,

V. Zhukov5

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

M. Ata, M. Brodski,E. Dietz-Laursonn, D. Duchardt, M. Erdmann, 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, H. Reithler,S.A. Schmitz, L. Sonnenschein, D. Teyssier,S. Thüer

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

V. Cherepanov, Y. Erdogan,G. Flügge, H. Geenen, M. Geisler, W. Haj Ahmad, F. Hoehle, B. Kargoll,

T. Kress, Y. Kuessel,A. Künsken, J. Lingemann2_{, A. Nowack,I.M. Nugent,C. Pistone, O. Pooth,A. Stahl}

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,I. Asin, N. Bartosik, J. Behr, U. Behrens,A.J. Bell, A. Bethani, 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, J. Garay Garcia, A. Geiser, A. Gizhko,

P. Gunnellini, J. Hauk, M. Hempel15_{, H. Jung,A. Kalogeropoulos, O. Karacheban}15_{, M. Kasemann,}

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

W. Lohmann15_{, B. Lutz,R. Mankel, I. Marfin}15_{, 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,

P.M. Ribeiro Cipriano, B. Roland,E. Ron, M.Ö. Sahin, J. Salfeld-Nebgen,P. Saxena, T. Schoerner-Sadenius,

M. Schröder, C. Seitz,S. Spannagel, A.D.R. Vargas Trevino,R. Walsh, C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

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

M. Hoffmann,R.S. Höing, A. Junkes, H. Kirschenmann,R. Klanner, R. Kogler, T. Lapsien, T. Lenz,

I. Marchesini, D. Marconi,J. Ott, T. Peiffer, A. Perieanu, N. Pietsch,J. Poehlsen, T. Poehlsen, D. Rathjens,

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

D. Troendle,E. Usai, L. Vanelderen,A. Vanhoefer

UniversityofHamburg,Hamburg,Germany

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

M. Feindt,F. Frensch, M. Giffels,A. Gilbert,F. Hartmann2, T. Hauth,U. Husemann, I. Katkov5,

A. Kornmayer2, P. Lobelle Pardo, M.U. Mozer, T. Müller,Th. Müller, A. Nürnberg, G. Quast, K. Rabbertz,

S. Röcker, H.J. Simonis,F.M. Stober, R. Ulrich, J. Wagner-Kuhr, S. Wayand,T. Weiler, R. Wolf

InstitutfürExperimentelleKernphysik,Karlsruhe,Germany

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

C. Markou, A. Psallidas, I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

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

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

UniversityofIoánnina,Ioánnina,Greece

G. Bencze,C. Hajdu, P. Hidas,D. Horvath16_{, F. Sikler,V. Veszpremi, G. Vesztergombi}17_,

A.J. Zsigmond

WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni,S. Czellar, J. Karancsi18,J. Molnar, J. Palinkas, Z. Szillasi

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

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

UniversityofDebrecen,Debrecen,Hungary

S.K. Swain

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

S.B. Beri,V. Bhatnagar, R. Gupta, U. Bhawandeep, A.K. Kalsi,M. Kaur, R. Kumar,M. Mittal, N. Nishu,

J.B. Singh

PanjabUniversity,Chandigarh,India

Ashok Kumar,Arun Kumar, S. Ahuja, A. Bhardwaj,B.C. Choudhary, A. Kumar,S. Malhotra, M. Naimuddin,

K. Ranjan,V. Sharma

UniversityofDelhi,Delhi,India

S. Banerjee, S. Bhattacharya, K. Chatterjee,S. Dutta, B. Gomber, Sa. Jain, Sh. Jain,R. Khurana,A. Modak,

S. Mukherjee,D. Roy, S. Sarkar, M. Sharan

SahaInstituteofNuclearPhysics,Kolkata,India

A. Abdulsalam,D. Dutta, V. Kumar, A.K. Mohanty2_{, L.M. Pant, P. Shukla,A. Topkar}

BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz,S. Banerjee, S. Bhowmik19_{, R.M. Chatterjee, R.K. Dewanjee,S. Dugad, S. Ganguly, S. Ghosh,}

M. Guchait,A. Gurtu20, G. Kole, S. Kumar, M. Maity19,G. Majumder, K. Mazumdar, G.B. Mohanty,

B. Parida,K. Sudhakar, N. Wickramage21

TataInstituteofFundamentalResearch,Mumbai,India

S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

H. Bakhshiansohi,H. Behnamian,S.M. Etesami22, A. Fahim23, R. Goldouzian, M. Khakzad,

M. Mohammadi Najafabadi,M. Naseri, S. Paktinat Mehdiabadi, F. Rezaei Hosseinabadi, B. Safarzadeh24,

M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b_{, C. Calabria}a,b_{, S.S. Chhibra}a,b_{,A. Colaleo}a_{, D. Creanza}a,c_{,L. Cristella}a,b_,

A. Pompilia,b_{,G. Pugliese}a,c_{,R. Radogna}a,b,2_{, G. Selvaggi}a,b_{, A. Sharma}a_{, L. Silvestris}a,2_{, R. Venditti}a,b_,

P. Verwilligena

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

G. Abbiendia_{,A.C. Benvenuti}a_{,D. Bonacorsi}a,b_{, S. Braibant-Giacomelli}a,b_{, L. Brigliadori}a,b_,

R. Campaninia,b_{, P. Capiluppi}a,b_{,A. Castro}a,b_{,F.R. Cavallo}a_{, G. Codispoti}a,b_{, M. Cuffiani}a,b_,

G.M. Dallavallea_{,F. Fabbri}a_{, A. Fanfani}a,b_{, D. Fasanella}a,b_{,P. Giacomelli}a_{,C. Grandi}a_{,L. Guiducci}a,b_,

S. Marcellinia, G. Masettia, A. Montanaria, F.L. Navarriaa,b_{,A. Perrotta}a_{, A.M. Rossi}a,b_{,T. Rovelli}a,b_,

G.P. Sirolia,b_{,N. Tosi}a,b_{, R. Travaglini}a,b

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

S. Albergoa,b_{,G. Cappello}a_{, M. Chiorboli}a,b_{, S. Costa}a,b_{, F. Giordano}a,c,2_{, R. Potenza}a,b_{, A. Tricomi}a,b_,

C. Tuvea,b

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

G. Barbaglia, V. Ciullia,b_{,C. Civinini}a_{, R. D’Alessandro}a,b_{,E. Focardi}a,b_{,E. Gallo}a_{,S. Gonzi}a,b_{,V. Gori}a,b_,

P. Lenzia,b_{,M. Meschini}a_{,S. Paoletti}a_{, G. Sguazzoni}a_{,A. Tropiano}a,b

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

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

INFNLaboratoriNazionalidiFrascati,Frascati,Italy

R. Ferrettia,b_{, F. Ferro}a_{, M. Lo Vetere}a,b_{, E. Robutti}a_{,S. Tosi}a,b

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

M.E. Dinardoa,b_{,S. Fiorendi}a,b_{, S. Gennai}a,2_{,R. Gerosa}a,b,2_{,A. Ghezzi}a,b_{,P. Govoni}a,b_{,M.T. Lucchini}a,b,2_,

S. Malvezzia_{, R.A. Manzoni}a,b_{,A. Martelli}a,b_{,B. Marzocchi}a,b,2_{,D. Menasce}a_{,L. Moroni}a_,

M. Paganonia,b_{,D. Pedrini}a_{,S. Ragazzi}a,b_{, N. Redaelli}a_{,T. Tabarelli de Fatis}a,b

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

S. Buontempoa_{, N. Cavallo}a,c_{, S. Di Guida}a,d,2_{, F. Fabozzi}a,c_{,A.O.M. Iorio}a,b_{,L. Lista}a_{, S. Meola}a,d,2_,

M. Merolaa, P. Paoluccia,2

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

P. Azzia_{,N. Bacchetta}a_{,D. Bisello}a,b_{,R. Carlin}a,b_{,A. Carvalho Antunes De Oliveira}a_{, P. Checchia}a_,

M. Dall’Ossoa,b_{,T. Dorigo}a_{, F. Gasparini}a,b_{, U. Gasparini}a,b_{,A. Gozzelino}a_{,K. Kanishchev}a,c_,

S. Lacapraraa_{,M. Margoni}a,b_{,A.T. Meneguzzo}a,b_{,J. Pazzini}a,b_{,M. Pegoraro}a_{, N. Pozzobon}a,b_,

P. Ronchesea,b_{,F. Simonetto}a,b_{, E. Torassa}a_{,M. Tosi}a,b_{, S. Vanini}a,b_{, P. Zotto}a,b_{, A. Zucchetta}a,b_,

G. Zumerlea,b

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

M. Gabusia,b_{,S.P. Ratti}a,b_{, V. Re}a_{,C. Riccardi}a,b_{,P. Salvini}a_{,P. Vitulo}a,b

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

M. Biasinia,b_{,G.M. Bilei}a_{,D. Ciangottini}a,b,2_{,L. Fanò}a,b_{, P. Lariccia}a,b_{, G. Mantovani}a,b_{, M. Menichelli}a_,

A. Sahaa, A. Santocchiaa,b_{,A. Spiezia}a,b,2

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

K. Androsova,25_{,P. Azzurri}a_{,G. Bagliesi}a_{,J. Bernardini}a_{,T. Boccali}a_{,G. Broccolo}a,c_{,R. Castaldi}a_,

M.A. Cioccia,25_{,R. Dell’Orso}a_{, S. Donato}a,c,2_{,G. Fedi, F. Fiori}a,c_{,L. Foà}a,c_{,A. Giassi}a_{, M.T. Grippo}a,25_,

F. Ligabuea,c_{,T. Lomtadze}a_{,L. Martini}a,b_{, A. Messineo}a,b_{, C.S. Moon}a,26_{, F. Palla}a,2_{, A. Rizzi}a,b_,

A. Savoy-Navarroa,27_{,A.T. Serban}a_{, P. Spagnolo}a_{, P. Squillacioti}a,25_{,R. Tenchini}a_{,G. Tonelli}a,b_,

A. Venturia,P.G. Verdinia,C. Vernieria,c

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

c_{ScuolaNormaleSuperiorediPisa,Pisa,Italy}

L. Baronea,b_{, F. Cavallari}a_{,G. D’imperio}a,b_{,D. Del Re}a,b_{, M. Diemoz}a_{,C. Jorda}a_{, E. Longo}a,b_,

F. Margarolia,b_{, P. Meridiani}a_{,F. Micheli}a,b,2_{,G. Organtini}a,b_{, R. Paramatti}a_{,S. Rahatlou}a,b_{, C. Rovelli}a_,

F. Santanastasioa,b_{, L. Soffi}a,b_{,P. Traczyk}a,b,2

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

N. Amapanea,b_{,R. Arcidiacono}a,c_{, S. Argiro}a,b_{, M. Arneodo}a,c_{,R. Bellan}a,b_{,C. Biino}a_{,N. Cartiglia}a_,

S. Casassoa,b,2_{, M. Costa}a,b_{,R. Covarelli,A. Degano}a,b_{,N. Demaria}a_{, L. Finco}a,b,2_{,C. Mariotti}a_,

S. Masellia,E. Migliorea,b_{, V. Monaco}a,b_{, M. Musich}a_{, M.M. Obertino}a,c_{, L. Pacher}a,b_{, N. Pastrone}a_,

M. Pelliccionia, G.L. Pinna Angionia,b_{,A. Potenza}a,b_{, A. Romero}a,b_{,M. Ruspa}a,c_{,R. Sacchi}a,b_,

A. Solanoa,b_{,A. Staiano}a_{, U. Tamponi}a

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

c_{UniversitàdelPiemonteOrientale,Novara,Italy}

S. Belfortea,V. Candelisea,b,2_{,M. Casarsa}a_{, F. Cossutti}a_{,G. Della Ricca}a,b_{, B. Gobbo}a_{, C. La Licata}a,b_,

M. Maronea,b_{, A. Schizzi}a,b_{, T. Umer}a,b_{,A. Zanetti}a

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

S. Chang,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,H. Park, A. Sakharov,D.C. Son

KyungpookNationalUniversity,Daegu,RepublicofKorea

T.J. Kim, M.S. Ryu

ChonbukNationalUniversity,Jeonju,RepublicofKorea

J.Y. Kim,D.H. Moon, S. Song

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

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

H.D. Yoo

SeoulNationalUniversity,Seoul,RepublicofKorea

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

UniversityofSeoul,Seoul,RepublicofKorea

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

SungkyunkwanUniversity,Suwon,RepublicofKorea

A. Juodagalvis

VilniusUniversity,Vilnius,Lithuania

J.R. Komaragiri, M.A.B. Md Ali,W.A.T. Wan Abdullah

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

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

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,S. Reucroft

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, M. Cwiok,W. Dominik, K. Doroba, A. Kalinowski, M. Konecki,J. Krolikowski,

M. Misiura, M. Olszewski

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

P. Bargassa,C. Beirão Da Cruz E Silva, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro,L. Lloret Iglesias,

F. Nguyen, J. Rodrigues Antunes, J. Seixas,J. Varela, P. Vischia

I. Golutvin, I. Gorbunov, A. Kamenev,V. Karjavin, V. Konoplyanikov, G. Kozlov, A. Lanev,A. Malakhov,

V. Matveev28_{,P. Moisenz, V. Palichik,V. Perelygin, M. Savina, S. Shmatov, S. Shulha, N. Skatchkov,}

V. Smirnov,A. Zarubin

JointInstituteforNuclearResearch,Dubna,Russia

V. Golovtsov,Y. Ivanov, V. Kim29,E. Kuznetsova, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov,

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

PetersburgNuclearPhysicsInstitute,Gatchina(St.Petersburg),Russia

Yu. Andreev,A. Dermenev,S. Gninenko, N. Golubev, 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, S. Semenov,

A. Spiridonov,V. Stolin, E. Vlasov,A. Zhokin

InstituteforTheoreticalandExperimentalPhysics,Moscow,Russia

V. Andreev,M. Azarkin30,I. Dremin30, M. Kirakosyan, A. Leonidov30,G. Mesyats, S.V. Rusakov,

A. Vinogradov

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Belyaev,E. Boos,V. Bunichev, M. Dubinin31,L. Dudko, A. Gribushin, V. Klyukhin, O. Kodolova,

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

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. Adzic32,M. Ekmedzic, J. Milosevic,V. Rekovic

UniversityofBelgrade,FacultyofPhysicsandVincaInstituteofNuclearSciences,Belgrade,Serbia

J. Alcaraz Maestre,C. Battilana, 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

H. Brun, J. Cuevas,J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero

UniversidaddeOviedo,Oviedo,Spain

J.A. Brochero Cifuentes,I.J. Cabrillo, A. Calderon, J. Duarte Campderros, M. Fernandez, G. Gomez,

A. Graziano,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, P. Bloch, A. Bocci, A. Bonato, O. Bondu,C. Botta, H. Breuker, T. Camporesi,

G. Cerminara, S. Colafranceschi33,M. D’Alfonso, D. d’Enterria, A. Dabrowski, A. David,F. De Guio,

A. De Roeck, S. De Visscher, E. Di Marco,M. Dobson, M. Dordevic, B. Dorney, N. Dupont-Sagorin,

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, M. Hansen,P. Harris,J. Hegeman, V. Innocente, P. Janot,

K. Kousouris,K. Krajczar, P. Lecoq,C. Lourenço, N. Magini, L. Malgeri,M. Mannelli, J. Marrouche,

L. Masetti, F. Meijers, S. Mersi,E. Meschi, F. Moortgat, S. Morovic, M. Mulders, L. Orsini, L. Pape,E. Perez,

A. Petrilli, G. Petrucciani,A. Pfeiffer, M. Pimiä, D. Piparo, M. Plagge, A. Racz,G. Rolandi34_{, M. Rovere,}

H. Sakulin, C. Schäfer, C. Schwick,A. Sharma,P. Siegrist, P. Silva,M. Simon, P. Sphicas35,D. Spiga,

J. Steggemann,B. Stieger, M. Stoye,Y. Takahashi, D. Treille, A. Tsirou, G.I. Veres17_{,N. Wardle, H.K. Wöhri,}

H. Wollny, 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, N. Chanon, G. Dissertori, M. Dittmar,

M. Donegà, M. Dünser,P. Eller, C. Grab,D. Hits, J. Hoss,G. Kasieczka, W. Lustermann,B. Mangano,

A.C. Marini,M. Marionneau, P. Martinez Ruiz del Arbol,M. Masciovecchio, D. Meister, N. Mohr,

P. Musella, C. Nägeli36_{, F. Nessi-Tedaldi, F. Pandolfi, F. Pauss,L. Perrozzi, M. Peruzzi,M. Quittnat,}

L. Rebane, M. Rossini,A. Starodumov37, M. Takahashi, K. Theofilatos,R. Wallny, H.A. Weber

InstituteforParticlePhysics,ETHZurich,Zurich,Switzerland

C. Amsler38, M.F. Canelli,V. Chiochia,A. De Cosa, A. Hinzmann, T. Hreus, B. Kilminster, C. Lange,

J. Ngadiuba,D. Pinna, P. Robmann, F.J. Ronga,S. Taroni, Y. Yang

UniversitätZürich,Zurich,Switzerland

M. Cardaci, K.H. Chen,C. Ferro, C.M. Kuo, W. Lin, Y.J. Lu, R. Volpe,S.S. Yu

NationalCentralUniversity,Chung-Li,Taiwan

P. Chang, Y.H. Chang,Y. Chao, K.F. Chen, P.H. Chen, C. Dietz, U. Grundler,W.-S. Hou, Y.F. Liu,R.-S. Lu,

M. Miñano Moya,E. Petrakou, Y.M. Tzeng,R. Wilken

NationalTaiwanUniversity(NTU),Taipei,Taiwan

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

ChulalongkornUniversity,FacultyofScience,DepartmentofPhysics,Bangkok,Thailand

A. Adiguzel, M.N. Bakirci39, S. Cerci40,C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut, Y. Guler,

E. Gurpinar,I. Hos, E.E. Kangal41, A. Kayis Topaksu,G. Onengut42, K. Ozdemir43,S. Ozturk39,A. Polatoz,

D. Sunar Cerci40,B. Tali40, H. Topakli39,M. Vergili, C. Zorbilmez

CukurovaUniversity,Adana,Turkey

I.V. Akin, B. Bilin,S. Bilmis, H. Gamsizkan44,B. Isildak45,G. Karapinar46,K. Ocalan47, S. Sekmen,

U.E. Surat,M. Yalvac, M. Zeyrek

MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E.A. Albayrak48_{,E. Gülmez,M. Kaya}49_{, O. Kaya}50_{,T. Yetkin}51

K. Cankocak,F.I. Vardarlı

IstanbulTechnicalUniversity,Istanbul,Turkey

L. Levchuk,P. Sorokin

NationalScientificCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine

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. Newbold52_{,S. Paramesvaran, A. Poll, T. Sakuma,S. Seif El Nasr-storey,}

S. Senkin,V.J. Smith

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell,A. Belyaev53,C. Brew, R.M. Brown, 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, W.J. Womersley,

S.D. Worm

RutherfordAppletonLaboratory,Didcot,UnitedKingdom

M. Baber,R. Bainbridge, O. Buchmuller, D. Burton,D. Colling, N. Cripps,P. Dauncey, G. Davies,

M. Della Negra,P. Dunne, A. Elwood, W. Ferguson, J. Fulcher, D. Futyan,G. Hall, G. Iles, M. Jarvis,

G. Karapostoli,M. Kenzie, R. Lane,R. Lucas52_{,L. Lyons, A.-M. Magnan, S. Malik,B. Mathias, J. Nash,}

A. Nikitenko37,J. Pela, M. Pesaresi, K. Petridis,D.M. Raymond, S. Rogerson, A. Rose,C. Seez, P. Sharp†,

A. Tapper,M. Vazquez Acosta, 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

J. Dittmann, K. Hatakeyama,A. Kasmi, H. Liu, N. Pastika, T. Scarborough,Z. Wu

BaylorUniversity,Waco,USA

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

TheUniversityofAlabama,Tuscaloosa,USA

A. Avetisyan, T. Bose,C. Fantasia, P. Lawson, C. Richardson, J. Rohlf, J. St. John,L. Sulak

BostonUniversity,Boston,USA

J. Alimena,E. Berry, S. Bhattacharya, G. Christopher, D. Cutts, Z. Demiragli, N. Dhingra, A. Ferapontov,

A. Garabedian,U. Heintz, E. Laird,G. Landsberg, Z. Mao, M. Narain, S. Sagir, T. Sinthuprasith, T. Speer,

J. Swanson

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,G. Rakness, E. Takasugi, V. Valuev, M. Weber

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

F. Lacroix,O.R. Long, A. Luthra, M. Malberti, M. Olmedo Negrete, A. Shrinivas,S. Sumowidagdo,

S. Wimpenny

UniversityofCalifornia,Riverside,Riverside,USA

J.G. Branson, G.B. Cerati,S. Cittolin, R.T. D’Agnolo, A. Holzner, R. Kelley, D. Klein, J. Letts, I. Macneill,

D. Olivito, S. Padhi, C. Palmer,M. Pieri, M. Sani, V. Sharma,S. Simon, M. Tadel,Y. Tu, A. Vartak,C. Welke,

F. Würthwein,A. Yagil, G. Zevi Della Porta

UniversityofCalifornia,SanDiego,LaJolla,USA

D. Barge, J. Bradmiller-Feld, C. Campagnari, T. Danielson, A. Dishaw,V. Dutta, K. Flowers,

M. Franco Sevilla,P. Geffert, C. George, F. Golf, L. Gouskos,J. Incandela, C. Justus,N. Mccoll, S.D. Mullin,

J. Richman, D. Stuart,W. To,C. West, J. Yoo

UniversityofCalifornia,SantaBarbara,SantaBarbara,USA

A. Apresyan,A. Bornheim, J. Bunn, Y. Chen, J. Duarte,A. Mott, H.B. Newman, C. Pena, M. Pierini,

M. Spiropulu, J.R. Vlimant,R. Wilkinson, S. Xie, R.Y. Zhu

CaliforniaInstituteofTechnology,Pasadena,USA

V. Azzolini,A. Calamba, B. Carlson, T. Ferguson, Y. Iiyama, M. Paulini,J. Russ, H. Vogel,I. Vorobiev

CarnegieMellonUniversity,Pittsburgh,USA

J.P. Cumalat, W.T. Ford,A. Gaz, M. Krohn, E. Luiggi Lopez,U. Nauenberg, J.G. Smith, K. Stenson,

S.R. Wagner

UniversityofColoradoatBoulder,Boulder,USA

J. Alexander, A. Chatterjee, J. Chaves,J. Chu, S. Dittmer, N. Eggert, N. Mirman, G. Nicolas Kaufman,

J.R. Patterson,A. Ryd, E. Salvati, L. Skinnari,W. Sun, W.D. Teo, J. Thom, J. Thompson, J. Tucker, Y. Weng,

L. Winstrom,P. Wittich

CornellUniversity,Ithaca,USA

D. Winn

FairfieldUniversity,Fairfield,USA

S. Abdullin,M. Albrow, J. Anderson, G. Apollinari, L.A.T. Bauerdick, A. Beretvas, J. Berryhill,P.C. Bhat,

G. Bolla,K. Burkett,J.N. Butler, H.W.K. Cheung, F. Chlebana, S. Cihangir, V.D. Elvira,I. Fisk, J. Freeman,

E. Gottschalk,L. Gray, D. Green, S. Grünendahl, O. Gutsche,J. Hanlon, D. Hare, R.M. Harris, J. Hirschauer,

B. Hooberman, S. Jindariani, M. Johnson,U. Joshi, B. Klima, B. Kreis, S. Kwan†,J. Linacre, D. Lincoln,

R. Lipton, T. Liu, R. Lopes De Sá,J. Lykken,K. Maeshima, J.M. Marraffino, V.I. Martinez Outschoorn,

S. Maruyama, D. Mason, P. McBride,P. Merkel,K. Mishra, S. Mrenna, S. Nahn, C. Newman-Holmes,

V. O’Dell, O. Prokofyev,E. Sexton-Kennedy, A. Soha, W.J. Spalding, L. Spiegel, L. Taylor,S. Tkaczyk,

N.V. Tran,L. Uplegger, E.W. Vaandering, R. Vidal, A. Whitbeck,J. Whitmore, F. Yang

FermiNationalAcceleratorLaboratory,Batavia,USA

D. Acosta, P. Avery, P. Bortignon, D. Bourilkov,M. Carver, D. Curry, S. Das, M. De Gruttola,

G.P. Di Giovanni, R.D. Field, M. Fisher, I.K. Furic, J. Hugon, J. Konigsberg,A. Korytov, T. Kypreos, J.F. Low,

K. Matchev, H. Mei,P. Milenovic54_{,G. Mitselmakher, L. Muniz,A. Rinkevicius, L. Shchutska, M. Snowball,}

D. Sperka, J. Yelton,M. Zakaria