Observation of a peaking structure in the J/psi phi mass spectrum from B-+/- -gt; J/psi phi K-+/- decays

SISTEMA DE BIBLIOTECAS DA UNICAMP

REPOSITÓRIO DA PRODUÇÃO CIENTIFICA E INTELECTUAL DA UNICAMP

Versão do arquivo anexado / Version of attached file:

Versão do Editor / Published Version

Mais informações no site da editora / Further information on publisher's website:

https://www.sciencedirect.com/science/article/pii/S0370269314003657

DOI: 10.1016/j.physletb.2014.05.055

Direitos autorais / Publisher's copyright statement:

©2014

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

Observation

of

a

peaking

structure

in

the

J

/ψφ

mass

spectrum

from

B

±

→

J

/ψφ

K

±

decays

.CMSCollaboration CERN, Switzerland a r t i c l e i n f o a b s t ra c t Article history: Received26September2013 Receivedinrevisedform11April2014 Accepted7May2014

Availableonline22May2014 Editor:M.Doser

A peakingstructure intheJ/ψφ massspectrum nearthreshold isobserved inB±_→J/ψφK± decays, produced in pp collisions at √s=7 TeV collected with the CMS detector at the LHC. The data sample, selectedon the basis ofthe dimuon decay mode of the J/ψ,corresponds to an integrated luminosity of 5.2 fb−1_{. Fitting the structure to an S-wave relativistic Breit–Wigner lineshape above}

athree-body phase-spacenonresonantcomponent givesasignal statistical significance exceedingfive standarddeviations.Thefittedmassandwidthvaluesarem=4148.0±2.4(stat.)±6.3(syst.)MeV and Γ =28+₋15₁₁ (stat.)±19(syst.)MeV,respectively.Evidenceforanadditionalpeaking structureathigher J/ψφmassisalsoreported.

©2014TheAuthors.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/3.0/).FundedbySCOAP3.

1. Introduction

The discovery of new charmonium-like states [1–6] over the last decade poses a challenge to the conventional quark model. Many explanations, such as charmed hybrids, tetraquarks, and molecular states,havebeen proposed forthesenew entities, but their nature remains a puzzle [7,8]. In 2009, the CDF Collabora-tionreported evidence fora narrow structure, whichthey called Y(4140), near the J/ψφ threshold in B±→J/ψφK± decays [9]. Thisstructure,ifconfirmedasanewresonance,wouldbea candi-dateforanexoticmeson[10–18].TheBelleCollaborationsearched forthe Y(4140)through the sameB± decaychannel [19] andin thetwo-photon process γ γ →J/ψφ [20],butdidnot confirmit. UsingthesameB±decaychannel,theLHCbCollaborationrecently reportedfindingnoevidenceforsuchastate,indisagreementwith theCDFresult[21].

InthisLetter,a studyofthe J/ψφ massspectrum fromB+→ J/ψφK+ decaysisreported,wherecharge conjugatedecaymodes areimpliedthroughout.Thedatawerecollectedin2011withthe CompactMuonSolenoid(CMS)detectorfromproton–proton colli-sionsattheLargeHadronCollider(LHC)operatingata center-of-massenergyof7 TeVandcorrespondingtoanintegrated luminos-ityof5.2±0.1 fb−1[22].

A detailed description of CMS can be found elsewhere [23]. The central feature of the CMS apparatus is a superconducting solenoid,13 mlongwitha6 minternaldiameter,whichprovides an axial magnetic field of 3.8 T. Within the field volume is the

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

silicontracker,whichconsistsofapixel-baseddetectorinthe in-ner region andlayers ofmicrostrip detectorsinthe outer region. Charged-particletrajectoriesaremeasuredwiththesilicontracker, covering0< φ≤2π inazimuthand|η|<2.5,wherethe pseudo-rapidity η isdefinedas−ln(tan[θ/2])andθ isthepolarangleof thetrajectoryoftheparticlewithrespecttothe counterclockwise-beam direction. Muons are detected in the pseudorapidity range |η|<2.4 by threetypes ofgas-ionization detectors embedded in thesteelflux-returnyokeofthemagnet:drifttubesinthebarrel, cathodestrip chambersinthe endcaps,andresistive-plate cham-bersinboththebarrelandendcaps.Thestrongmagneticfieldand excellentpositionresolutionofthesilicontrackerenablethe trans-versemomentum(pT)ofamuonmatchedtoareconstructedtrack

tobemeasured witharesolutionofapproximately0.7%for pT of

1 GeV.Thepixeldetector,withitsexcellentspatialresolutionand low occupancy, enables theseparation ofB+-decay verticesfrom theprimaryinteractionvertex.

Monte Carlo(MC) simulated data were createdusing pythia6

[24] for the particle production, evtgen [25] for theparticle de-cays, and Geant4[26]fortracing theparticlesthrough adetailed model ofthe detector. Thesesamples were created withthe ap-propriateconditionsforthedataanalyzed,includingtheeffectsof alignment,efficiency,andnumberofsimultaneousppcollisions.

2. Eventselection

Events are chosen using a two-level trigger system. The first level,composed ofcustomhardware processors,uses information fromthe muon detectors toselect dimuon candidates.The high-level trigger (HLT) runs a special version of the offline software http://dx.doi.org/10.1016/j.physletb.2014.05.055

0370-2693/©2014TheAuthors.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/3.0/).Fundedby SCOAP3_.

Fig. 1. TheJ/ψφK+massdistributionwiththestandardeventselection(left)andthetighterrequirements(right).Thesolidcurvesshowtheresultoffittingthesedistributions toaGaussiansignalandasecond-degreepolynomialbackgroundwhilethedashedcurvesshowthebackgroundcontribution.

code on a processor farm to select events with nonprompt J/ψ

candidatescomingfromthedecaysofB mesons.

Events containing J/ψ candidates are selected by the HLT dimuontrigger.BecauseoftheincreasingLHCinstantaneous lumi-nosity, thereare two configurations of theHLT, corresponding to tworunningperiodsandtwodistinctdatasets.Forbothdatasets, thefollowingrequirementsare alreadyappliedwiththeHLT.The dimuonpTisrequiredtobegreaterthan6.9 GeV,thetwomuons

must be oppositely charged and form a three-dimensional (3D) vertexwitha χ2 _{probability greater than0.5–10%,depending on}

the running period. The resulting J/ψ vertex must be displaced from the average interaction point (beamspot) in the transverse planeby atleastthreetimesitsuncertainty,which isthesumin quadratureofthesecondary-vertexuncertaintyandthebeamspot sizeinthetransverse plane.Thecosine ofthe anglebetweenthe transverseprojectionsofthelinejoiningthebeamspotanddimuon vertexandthedimuonmomentumdirectionmustexceed0.9.For thelaterdataset,thereisanadditionalrequirementthatthepT of

eachmuonbegreaterthan4 GeV.InthefinalselectionofJ/ψ can-didates,thedimuon pT isrequiredto begreater than7 GeV,the

χ2 _{probability of the dimuon vertex is demanded to be greater}

than 10%,and thereconstructed dimuon invariant massmust be within150 MeVoftheJ/ψ mass[27].

TheB+→J/ψφK+ candidatesare reconstructedby combining three additional charged-particle tracks that are consistent with originatingfromthedisplacedJ/ψ vertexandhaveatotalcharge of ±1. These tracks are assigned the kaon mass and this mass isusedin accountingfortheeffectsofenergyloss and multiple-scattering.Wedonotapply amassconstraintontheφ candidate becauseourexperimental K+K− massresolution(1.3 MeV)isless than the φ meson natural width (4.3 MeV). The pT of all kaon

tracks are required to be greater than 1 GeV. Only tracks that pass the standard CMS quality requirements [28] are used. The fivetracks,withthe μ+μ− invariantmassconstrainedtotheJ/ψ

mass,arerequiredtoforma good3Dvertexwitha χ2

probabil-itygreater than 1%. There are two K+K− combinations fromthe three chargedkaon tracks, andwe use the lower invariant mass astheφ candidate; MCsimulations ofthe B+ decaypredict that the φ signal from the other combination is negligible, which is verifiedinthedata.ThereconstructedK+K−invariant massmust satisfy 1.008 GeV<m(K+K−)<1.035 GeV to be considered asa

φcandidate.Theseselectionrequirementsweredesignedto main-tainhighefficiencyforB+ decaysandwerefixedbeforetheJ/ψφ

massspectrumindatawasexamined.

3. Results

The invariant-mass spectrum of the selected J/ψφK+ candi-dates is shown in the left plot of Fig. 1 for a mass difference

m≡m(μ+μ−K+K−)−m(μ+μ−)<1.568 GeV. We only inves-tigate candidateswithm<1.568 GeV becauseofpossible back-groundfromB0_s→ ψ(2S)φ→J/ψπ+π−φathighervalues,as dis-cussed below.Theinvariant-mass spectrumisfitwithaGaussian signal functionandasecond-degreepolynomialbackground func-tion. The fit returns a B+ mass of 5.2796±0.0006 (stat.)GeV, which agreeswiththe nominalvalue [27],andaGaussian width of 9.6±0.7 (stat.)MeV, which is consistent with the prediction fromtheMCsimulation.TheB+yieldis2480±160(stat.)events, whichistheworld’slargestB+→J/ψφK+ sample.Thecombined B+yieldis2340±120(stat.)eventswheneachdatasetisfitwith two Gaussian signal functions andthe width ofeach function is fixed to theprediction fromMC simulation.Approximately 5% of the selected eventshavemore thanone B+ candidatewithin 1.5 timesourmassresolution(σ)ofthe B+ mass;allcandidates are kept.

TherightplotinFig. 1displaystheJ/ψK+K−K+invariant-mass distribution after making the following tighter requirements: the pT of the kaons must be greater than 1.5 GeV, the B+ vertex

probability mustbegreaterthan 10%, theB+ vertexmustbe dis-placedfromtheprimaryvertexinthetransverseplanebyatleast seven timesitsuncertainty,andm(K+K−)mustbe within7 MeV of the φ meson mass [27]. With theserequirements, 40% of the B+ candidates are retained, while the background is reducedby more than a factor of ten. This sample of cleaner signal candi-datesisusedasacross-checkoftheresultsobtainedbyemploying the background-corrected J/ψφ mass spectrum, asdescribed be-low.Withtheexceptionofthiscross-check,allresultsareobtained withtheless-restrictivecriteria.

Fig. 2 shows the K+K− invariant-mass distribution for J/ψK+K−K+ candidatesthat have an invariant mass within ±3σ of the B+ mass. We define events in the range [−12,−6]σ and [6,12]σ oftheB+ massassidebands.Theφ massrestrictionhas beenremoved andasidebandsubtractionhasbeenperformedin

Fig. 2.WefitthisdistributiontoaP -waverelativisticBreit–Wigner (BW) functionconvolvedwithaGaussian resolutionfunction.The widthoftheGaussianisfixedto1.3 MeV,obtainedfromMC sim-ulation. The fit has a χ2 _{probability of 23% andreturns a mass}

of 1019.4±0.1 MeV and a width of 4.7±0.4 MeV, consistent with the φ meson [27]. The good fit to only a φ component in Fig. 2 indicates that after the J/ψ and φ mass requirements are made and the combinatorial background is subtracted, the

Fig. 2. The B+ sideband-subtracted K+K− invariant-mass distribution for J/ψK+K−K+candidateswithin±3σ ofthenominalB+ mass.Thesolidcurveis theresultofthefitdescribedinthetext.Thedashedlineshowsthezero-candidate baseline.

B+→μ+μ−K+K−K+ candidates are consistentwithbeingsolely J/ψφK+,withnegligiblecontribution fromJ/ψf0(980)K+ or

non-resonantJ/ψK+K−K+.

As seen in Fig. 1, there are two main components to the J/ψφK+ invariant-mass spectrum: the B+ signal and a smooth background.PossiblecontributionsfromotherB-hadrondecaysare examinedusingMCsimulationsofinclusiveB+,B0,andB0_s decays. Basedonthisstudy,themass-differenceregion(m>1.568 GeV) isexcluded fromtheanalysistoavoidpotential backgroundfrom B0_s→ ψ(2S)φ→J/ψπ+π−φ decays, whereone pion isassumed tobeakaonandtheotherisnotreconstructed.

ToinvestigatetheJ/ψφinvariant-massdistribution,ratherthan fitting the distribution itself with its large combinatorial back-ground, the J/ψφK+ candidates are divided into 20 MeV-wide

m intervals,and theJ/ψφK+ massdistributions for each inter-valare fit toextract the B+ signal yieldin that interval. Weuse asecond-degreepolynomialforthecombinatorialbackgroundand twoGaussiansfortheB+signal.Thefitisperformedseparatelyfor eachdataset.The meanvaluesofthe twoGaussiansarefixed to theB+mass[27],andthewidthvaluesoftheGaussians,aswellas theirrelativeratio,arefixed tothevaluesobtainedfromMC sim-ulationforeach specificm intervalineachdataset.Theresults ofallthefits aregooddescriptions ofthedatadistributions with anaverage χ2 _{perdegreeoffreedom(dof)closeto1.Theresulting} m distributionforthecombineddatasetsisshowninFig. 3.Two peakingstructuresare observedabove thesimulatedphase-space (PS)continuumdistributionshownbythedottedline.

Results obtainedfrom both data sets are consistent. We have checkedthateventswithmultipleB+candidatesdonotartificially enhancethetwo structures.ThetotalnumberofB+ signalevents inthem intervalsbelow1.568 GeVis2320±110(stat.),whichis consistentwiththetotalnumberofB+ candidatesestimatedfrom themassspectruminFig. 1.

A full study of the J/ψφ resonant pattern in the B+ → μ+μ−K+K−K+ decay via an amplitude analysisof the five-body decaywouldrequireadatasampleatleastanorderofmagnitude largerthaniscurrentlyavailable,aswellasmoreprecise informa-tiononpossibleφK+orJ/ψK+resonancesthatmaycontributeto thisdecay.Instead, them distributionis studied,since it is re-latedtotheprojectionofthetwo-dimensional(2D)J/ψφK+Dalitz plotontothem2(J/ψφ)axis.

Beforefittingthem distribution,itmustbecorrectedforthe relativedetection andreconstruction efficienciesof thecandidate events. Since no branching fractions are being determined, only the relative efficiency over the Dalitz plot is required. If a

pos-Fig. 3. The number of B+ →J/ψφK+ candidates as a function of m = m(μ+μ−K+K−)−m(μ+μ−).Thesolidcurve istheglobalunbinned maximum-likelihood fit ofthe data, and the dottedcurve is the backgroundcontribution assumingthree-bodyPS.Thebandisthe±1σuncertaintyrangeforthebackground obtainedfromtheglobalfit.Thedashedanddash-dottedcurvesarebackground curvesobtainedfromtwodifferentevent-mixingprocedures,asdescribedinthe text,andnormalizedtothenumberofthree-bodyPSbackgroundevents.Theshort dashedcurveisthe1Dfittothedata.

sible φK+ or J/ψK+ resonance did exist, the density of events woulddependonthequantumnumbersoftheresonanceandon theinterferenceofthetwostructureswiththepossibleresonance. Ignoring thesepossible interference effects,the MC simulation is used todetermine theefficiencyover them2(φK+) vs.m2(J/ψφ)

Dalitz plot,assuming a PS distribution for the three-body decay B+→J/ψφK+.TheJ/ψandφvectormesondecaysaresimulated usingtheir knownangulardistributions accordingto theVLLand VSS model in evtgen, while we assume there is no polarization forthetwovectors.ThePSMCsimulationisreweightedassuming either transverse orlongitudinal J/ψ and φ polarization. The ef-fectofeitherpolarizationisfoundtobenegligible.Themeasured efficiencyisfairly uniform,varying bylessthan25% overthe en-tire allowed three-body PS. Assuming a uniform PS distribution, the efficiencyforeach m binis takento be the averageof the efficiencies over the fullkinematically allowed m(φK+) range.To estimatethesystematicuncertaintyintheefficiencycausedbyits dependenceontheunknownquantumnumbersofthestructures, andhence ontheir unknown decay angulardistributions, the ef-ficiency is evaluated under the assumption of both a cos2θ and sin2θ dependence,where θ is the helicity angle, defined as the anglein the J/ψφ rest framebetween thedirectionof theboost from the laboratory frame and the J/ψ direction. Since the effi-ciencytends tobe lower towardstheedge oftheDalitz plot,the cos2_{θ dependence gives a lower average efficiency than the}

de-faultefficiency,whilethesin2θdependencegivesaslightlyhigher average efficiency.Thisvariation (10%) istakenas thesystematic uncertainty in the efficiency from our lack of knowledge of the quantumnumbersofthestructuresandtheeffectsofinterference withpossibletwo-bodyresonances.

We investigate the possibility that the two structures in the

m distribution arecausedby reflectionsfromresonancesin the other two-body systems, J/ψK+ and φK+. Such reflections are well known in the two-bodysystems from other three-body de-cays because ofkinematic constraints.There are candidate states that decay to φK+ [27], although they are not well established. These could potentially produce reflected structures inthe J/ψφ

spectrum. In particular, a D-wave contribution to K−p scatter-ing in the mass region around 1.7–1.8 GeV has been reported byseveralfixed-targetexperiments[29–31].This isinterpretedas two interferingbroad JP₌₂− _{resonances, labeled K2(1770) and}

Fig. 4. TheyieldofB+→J/ψK+K−K+candidatesinthedataasafunctionofthe K+K−K+ invariantmass.Theerrorbarsrepresentthestatisticaluncertainties.The solidcurveisthepredictionfromthePSsimulation.

K2(1820), with widths in the range 200–300 MeV. These

reso-nancesatrelatively lowφK+masscannotaffecttheJ/ψφstructure near threshold, but could contribute to the second J/ψφ struc-ture near m=1.2 GeV. To study possible reflections from the

φK+ spectrum,we considerφK+resonances withvariousmasses, widths,andhelicityangledistributions,butarenotableto repro-ducethe patternofstructuresseeninthe J/ψφ spectrum. More-over, we separately analyze the J/ψφ spectrum forvalues ofthe

φK+ masseslargerthan1.9 GeV, aregionoftheDalitzplot unaf-fectedby postulatedφK+ resonances,andstillobserve the struc-turenearm=1.2 GeV.

There are nocandidate J/ψK+ resonancesreported inthe lit-erature. Still, we have considered such resonances with various masses, widths, and helicity angle distributions. No combination produces a reflected spectrum that matches the observed J/ψφ

spectrum.

Wehavealsocheckedtheeventswithm largerthan1.568 GeV that had been eliminated from the analysis to ensure that they could not cause similar reflections in the low-m region. After subtraction of the B0_s background the m distribution of events withm larger than 1.568 GeVisconsistent withthe prediction based on the three-body phase-space hypothesis for the non-resonantbackground.(Pleaseseethesupplementalmaterialinthe online version at http://dx.doi.org/10.1016/j.physletb.2014.05.055

forplots.)

The results ofthese studies make it improbable that the two structuresseen inthe J/ψφ spectrumaresolelycausedby

reflec-tionsfromresonancesintheothertwo-bodysystems.However,we cannot entirelyexcludethepossibilityofsuchresonances.For in-stance, theK+K−K+ spectrumshowninFig. 4displays an excess of events above the predictedPS distribution in the 1.7–1.8 GeV region,an excessthatcannotbe attributedtothepresenceofthe J/ψφ structure nearthreshold. Fig. 4is obtainedby dividing the J/ψφK+candidatesinto40 MeV-wideK+K−K+massintervalsand fittingtheJ/ψφK+invariant-massdistributionsforeachintervalto extracttheB+signalyieldinthatinterval.Them distribution af-terexcludingtheregion(1.68<m(K+K−K+)<1.88 GeV)withthe excessofeventsisshownintheleft plotofFig. 5andthe corre-spondingdistributionfortheexcludedm regionintherightplot. The presence of thelower-mass structure is still apparent in the leftplot,whilethatofthehigher-massstructureisreducedthough still visible.PossibleinterferenceeffectsovertheDalitzplotcould thereforedistorttheshapeoftheobservedJ/ψφ structuresand af-fecttheextractionoftheresonanceparameters.Theeventsample isnotlargeenoughtoinvestigatetheseeffectsfurther.Weassume thatanyinterferenceeffectscanbeneglected.Thestructuresinthe J/ψφ massspectrum are described intermsof zero,one,ortwo noninterfering resonances anda nonresonant continuum compo-nent.

We fit the two structures with S-wave relativistic BW func-tions convolved witha Gaussian mass resolution function whose widthvarieslinearlyfrom1 MeVatthresholdtoabout4 MeVat

m=1.25 GeV,asdeterminedfromsimulation.Eachstructureis described by a mass, width, and yield, all determined from the fit.Thecontinuumisassumedtofollowathree-bodyPSshape.As analternative,tocheckthesensitivityoftheresulttothis assump-tion,theshapeofthecontinuumisobtainedfromanevent-mixing technique wherethe J/ψ,φ,andK+candidatesareselectedfrom differentevents.Weusetwo versionsofthe eventmixing, which differbytheφandK+candidatesbeingselectedinthesameevent or not; they lead to almost identicalshapes. The differences be-tween the two event-mixing shapes and the three-body PS are used to evaluate the systematic uncertainties in the continuum modeling.TofurtherinvestigatetheeffectofapossibleφK+ reso-nancearound1.7 GeVasshowninFig. 4,wereweightour phase-spaceMCeventswithaφK+massdistributioncorrespondingtoa BW witha massof1.773 GeV andawidthof200–300 MeV[27]. The helicity angle in the φK+ system is then weighted to cor-respond to several different assumptions about the decay of the possibleresonance.WeestimatetheyieldofthepossibleφK+ res-onance inFig. 4tobe10%ofthetotalnumberofevents.Wefind thattheshapeofthePSm distributionisalwaysabove the var-ious distributions obtained from the above mixing in the range

m<1.12 GeV.Thus, weconcludethatusingthe PSdistribution

Fig. 5. ThenumberofB+→J/ψφK+candidatesasafunctionofm requiring either m(φK+)<1.68 GeV or m(φK+)>1.88 GeV (left),or1.68<m(φK+)<1.88 GeV (right). ThesolidcurveisthepredictionfromthePSsimulation.

asthedefaultbackgroundcurveismoreconservativewithrespect tothesignificanceofthelow-masspeakifthereisapossibleeffect fromaφK+resonance.

Themassesandwidthsofthetwo structuresare extractedby dividing the J/ψφK+ candidates into 20 MeV-wide intervals of

m from 1.008 to 1.568 GeV and performing a globalunbinned maximum-likelihood(UML)fittotheJ/ψφK+ invariant-mass dis-tribution in each m interval. The two data sets are fitted sep-arately, witha total of 56 mass spectra fitted simultaneously. In eachfit, theB+ massis fixed toits nominalvalue and themass resolutionδiscalculatedusing:

δ=a0+a1m +a2m2,

wheremisthevalue ofm atthe centerofthebin,anda0,

a1,anda2 aredeterminedfromsimulation,separatelyforthetwo

datasets.Thecombinatorialbackgroundineachbinismodeledas asecond-degreepolynomial. Inthe globalfit, theB+ yieldis ex-pressedastheproductoftherelativeefficiencytimesthenumber ofsignal eventsfrom the two BWsand the nonresonant contin-uum events. We fit the J/ψφK+ invariant-mass distribution for each m bin fromthe two data sets simultaneously by project-ing the above product into each bin. The UML fit returns signal eventyieldsof310±70(stat.)and418±170(stat.)forthe lower-andhigher-massstructures, respectively. The corresponding mass differenceandwidthvaluesare: m1=1051.3±2.4(stat.)MeV, Γ1=28+₋15₁₁ (stat.)MeV; m2=1217.1±5.3 (stat.)MeV, Γ2 =

38+₋30₁₅ (stat.)MeV. The projection of the UML fit assuming two structuresontotheJ/ψφ massspectrumisrepresentedasthesolid lineinFig. 3.

Asacheckonthefittingprocedure,we performanalternative one-dimensional(1D)binned χ2 _{fittothem spectrumshownin}

Fig. 3.Thesamesignal andbackgroundfunctionsare usedinthe 1Dfit asintheglobalfit.The resultofthe 1D fit,assuming two structures,isshownasthedashedlineinFig. 3.Themeasurements ofthemasses, widths, andyields ofthe two structuresfromthe globaland1Dfitsareingoodagreement.

Toevaluatethesignificanceofeachofthetwostructures,three UML and three 1D (binned χ2_{) fits are performed on the data}

showninFig. 3:(1) abackground-onlyfit(null-hypothesis);(2) a background plus a single S-wave relativistic BW signal function convolvedwitha Gaussian resolution function havinga widthof 2 MeVfor the lower-mass structure; and(3) a background plus two S-wave relativistic BW functions convolved witha Gaussian resolutionfunctiontomodelbothstructures.Thelog-likelihood ra-tio−2lnLinthecaseoftheUMLfitsorthe χ2_changeχ2 _for

the1Dfitsbetween(1)and(2)isthenameasureofthestatistical significanceofthe lower-massstructure, whilethe corresponding values betweenfits (2)and (3) give a measure of the statistical significanceofthehigher-massstructure. Theresultingvalues for a decreasein dofof 3 are −2lnL=58 and χ2_{=53 for the}

lower-mass structure, and 36 and 37 for the higher-mass struc-ture.

Simulated samples are used to estimate the probability that background fluctuationsalone could give rise to a signal as sig-nificant as that seen in the data for the lower-mass structure. Over 50 million m spectra were generated between 1.008 and 1.568 GeVwith2300eventsforeachspectrum basedona three-bodyPS shape.Themostsignificant fluctuationineach spectrum isfound whose J/ψφ invariant mass iswithin ±3 timesthe un-certaintyintheCDFmassvalue of4.140 GeVandhavingawidth between 10 MeV (half the m bin width) to 80 MeV (half the separationbetweenthetwo structures).We thenobtaintheχ2

distributionsinthesimulatedpurebackgroundsamplesand com-parethemwiththecorresponding valueofthesignal inthedata.

Table 1

Systematicuncertaintiesinthemeasuredmassesandwidthsofthetwopeaking structuresfromthesourceslistedandthetotaluncertainties.

m1(MeV) Γ1(MeV) m2(MeV) Γ2(MeV)

B+background PDF 0.8 7.4 2.6 9.9 B+signal PDF 0.2 3.6 2.7 0.2 Relative efficiency 4.8 6.0 0.9 10.0 m binning 3.7 1.5 2.7 0.2 m structure PDF 0.8 9.3 0.6 4.9 m mass resolution 0.8 6.4 0.6 4.6 m background shape 0.2 7.0 0.3 0.2 Selection requirements 0.8 7.8 5.5 1.8 Total 6.3 19 7.3 16

No generatedspectrumisfoundwithafluctuationhavinga χ2

greater thanorequal tothevalue obtainedin thedata(53).The resulting p-value, takenasthe fractionof thesimulated samples with a χ2 _{value greater than or equal to the value obtained}

in the data, is less than 2×10−8, which corresponds to a sig-nificance of more than 5 standard deviations. Because the sec-ond structure could be affected by possible φK+ resonances, it is difficult to model the background shape in that mass range, andwe do not quote a numeric significancefor the higher-mass structure.However, there isclearevidencefora second structure around m=1.2 GeV even afterexcluding the region with pos-sibleK2 resonances.There isalsoasmallexcessofeventsaround m=1.4 GeV,butwithalocalsignificanceoflessthan3standard deviations.

Variouschecksaremadetoexaminetherobustnessofthetwo structures. Each selection criterion is individually varied, and in no case is there an indication of a bias in the selection proce-dure.Therelative efficienciesforthefirstfivem binsarevaried by ±20% and the fit repeated, confirming the robustness of the significance of the first structure. The m distribution from an sPlot [32] projection is compared to the m distribution shown in Fig. 3.No indication ofbias isfound. The sPlotalgorithm isa background-subtraction technique that weights each event based onthe observedsignal-to-background ratio,inthiscasefromthe fittotheJ/ψφK+massdistributionshowninFig. 1.Werepeatthe analysiswiththetighterrequirementsdiscussedearlierthatlower the combinatorial backgroundlevel by a factor often andretain 40%oftheB+events,asshownintherightplotinFig. 1.Them plot for these events looks similar to Fig. 3, showing two peak-ing structureswhosefittedmassandwidth valuesareconsistent withtheresultsfromthenominaldatasample.No indicationofa possiblebiasisfound.

The estimations of the contributions to the systematic uncer-taintiesinthemassandwidthmeasurementsofthetwostructures showninTable 1,aredeterminedfromseveralstudies.The uncer-tainties owing tothe probability densityfunctions(PDFs)forthe combinatorialbackgroundshapeinthem(J/ψφK+)spectrumand the B+ signal are studied by using different PDFs such as first-andthird-degree polynomials, exponential functions, anda num-ber of Gaussian functions. The uncertainties in the shape of the relativeefficiencyvs. m areevaluatedbyvaryingtherelative ef-ficiencyinvariousbinsandcomparingwiththe2Defficienciesfor correctionofm(J/ψφ)vs.m(φK+).Theuncertaintiescausedbythe binningofthem spectrumarestudiedbyusing10 MeVbins in-steadof20 MeVbins.Toestimate theuncertaintyfromthesignal fittingfunction,werepeatthefittothem distributionusing ei-theranonrelativisticBWora P -waverelativisticBW functionfor eachstructure.Theuncertaintiesfromthem massresolutionare studiedbyvaryingthemassresolutionvaluesobtainedfrom sim-ulation withintheir statistical uncertainties.Toevaluate potential distortions inthe m background shapecausedby possible φK+

resonances,weobtainthem backgroundshapefromdatausing an event-mixing technique by applyingthe same kinematic con-straintsandtakingtheφandK+candidatesfromthesameevent, buttheJ/ψcandidatefromadifferentevent.Theuncertaintiesdue toselectionrequirementsarestudiedintheMCsample.The over-allsystematicuncertaintiesinthemeasurementofthemassesand widths of the two structures are found by adding in quadrature theindividualcombinationssummarizedinTable 1.

4. Summary

In summary, a peaking structure in the J/ψφ mass spectrum fromB+→J/ψφK+ decays hasbeenobservedinpp collisions at √

s=7 TeV by the CMS Collaboration at the LHC. Assuming an S-waverelativisticBW lineshapeforthisstructure abovea three-bodyPSshapeforthenonresonantbackground,astatistical signif-icanceofgreater than5standard deviationsisfound. Addingthe J/ψ mass [27] to the extracted m values, the mass and width aremeasuredtobem1=4148.0±2.4(stat.)±6.3(syst.)MeV and Γ1=28+₋1511(stat.)±19(syst.)MeV.Themeasuredmassandwidth

are consistent with the Y(4140) values reported by CDF experi-ment.Therelativebranchingfractionofthispeakingstructurewith respecttothetotal numberofB+→J/ψφK+ eventsisestimated tobe about0.10,withastatisticaluncertaintyofabout 30%. This is consistent with both the value measured by CDF of 15%±5% andtheupperlimitreportedbyLHCb(0.07).Inaddition,evidence fora second peaking structure is found in the same mass spec-trum, with measured mass and width values of m2=4313.8±

5.3(stat.)±7.3(syst.)MeV andΓ2=38+₋3015(stat.)±16(syst.)MeV.

Becauseofpossiblereflectionsfromtwo-bodydecays,the statisti-cal significance of the second structure cannot be reliably deter-mined. The two structures are well above thethreshold of open charm (DD) decays and have relatively narrow widths. Conven-tionalcharmoniummesonswiththesemasseswouldbeexpected tohavelargerwidthsandtodecaypredominantlyintoopencharm pairswithsmallbranchingfractionsintoJ/ψφ.Angularanalysesof theB+→J/ψφK+decayswouldhelpelucidatethenatureofthese structures.

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 the following funding agencies: BMWF andFWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES(Bulgaria);CERN;CAS,MoST,andNSFC(China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 andERDF(Estonia);Academy ofFinland,MEC,andHIP(Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT(Greece);OTKAandNKTH(Hungary);DAEandDST(India); IPM(Iran);SFI (Ireland);INFN (Italy);NRF andWCU(Republic of Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland);FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS andRFBR(Russia);MESTD(Serbia);SEIDIandCPAN(Spain);Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine);STFC(UnitedKingdom);DOEandNSF(USA).

Individuals have received support from the Marie-Curie pro-gramme and the European Research Council and EPLANET (Eu-ropean Union); the Leventis Foundation; the A.P. Sloan Founda-tion; the Alexander von Humboldt Foundation; the Belgian Fed-eral Science Policy Office; the Fonds pour la Formation à la Recherchedansl’Industrieetdansl’Agriculture(FRIA-Belgium);the AgentschapvoorInnovatiedoorWetenschapenTechnologie (IWT-Belgium); the MinistryofEducation, Youth andSports(MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programmeofFoundationForPolishScience,cofinancedbyEU, Re-gionalDevelopmentFund;andtheThalisandAristeiaprogrammes cofinancedbyEU-ESFandtheGreekNSRF.

References

[1] S.K. Choi, et al., Belle Collaboration, Observation of a new narrow char-monium state in exclusive B+→K+π+π−J/ψ decays, Phys. Rev. Lett. 91 (2003),http://dx.doi.org/10.1103/PhysRevLett.91.262001,262001,arXiv:hep-ex/ 0309032.

[2] D. Acosta, et al., CDF Collaboration, Observation of the narrow state X(3872)→J/ψπ+π− inpp collisions¯ at√s=1.96 TeV,Phys.Rev.Lett.93 (2004),http://dx.doi.org/10.1103/PhysRevLett.93.072001,072001,arXiv:hep-ex/ 0312021.

[3] V.M. Abazov, et al., D0 Collaboration, Observation and properties of the X(3872) decaying to J/ψπ+π− in pp collisions¯ at √s=1.96 TeV, Phys. Rev.Lett.93(2004),http://dx.doi.org/10.1103/PhysRevLett.93.162002,162002, arXiv:hep-ex/0405004.

[4] B.Aubert,etal.,BaBarCollaboration,StudyoftheB−→J/ψK−π+π− decay andmeasurementoftheB−→X(3872)K−branchingfraction,Phys.Rev.D71 (2005), http://dx.doi.org/10.1103/PhysRevD.71.071103, 071103, arXiv:hep-ex/ 0406022.

[5] K. Abe, et al., Belle Collaboration, Observation of a near-threshold ωJ/ψ

mass enhancement in exclusive B→KωJ/ψ decays, Phys. Rev. Lett. 94 (2005),http://dx.doi.org/10.1103/PhysRevLett.94.182002,182002,arXiv:hep-ex/ 0408126.

[6] B. Aubert, et al., BaBar Collaboration, Observation of Y(3940)→J/ψω in B→J/ψωK at BaBar,Phys. Rev.Lett.101(2008), http://dx.doi.org/10.1103/ PhysRevLett.101.082001,082001,arXiv:0711.2047.

[7] S.L.Olsen,RecentresultsfromBaBar,Belle,BESIIIandCDF,AIPConf.Proc.1343 (2011)129,http://dx.doi.org/10.1063/1.3574954,arXiv:1011.5307.

[8] N. Brambilla, et al., Heavy quarkonium: progress, puzzles, and opportuni-ties,Eur.Phys.J.C71(2011)1534, http://dx.doi.org/10.1140/epjc/s10052-010-1534-9,arXiv:1010.5827.

[9] T.Aaltonen,et al.,CDF Collaboration,Evidence for anarrownear-threshold structureintheJ/ψφmassspectruminB+→J/ψφK+decays,Phys.Rev.Lett. 102(2009), http://dx.doi.org/10.1103/PhysRevLett.102.242002, 242002, arXiv: 0903.2229.

[10] X.Liu,S.-L.Zhu,Y(4143)isprobablyamolecularpartnerofY(3930),Phys. Rev.D80(2009),http://dx.doi.org/10.1103/PhysRevD.80.017502,017502,arXiv: 0903.2529.

[11] N.Mahajan,Y(4140):possibleoptions,Phys.Lett.B679(2009)228,http:// dx.doi.org/10.1016/j.physletb.2009.07.043,arXiv:0903.3107.

[12] T. Branz, T. Gutsche, V.E. Lyubovitskij, Hadronic molecule structure of the Y(3940) and Y(4140), Phys. Rev. D 80 (2009), http://dx.doi.org/10.1103/ PhysRevD.80.054019,054019,arXiv:0903.5424.

[13] R.M.Albuquerque,M.E.Bracco, M.Nielsen,A QCD sumrulecalculation for theY(4140)narrowstructure,Phys.Lett.B678(2009)186,http://dx.doi.org/ 10.1016/j.physletb.2009.06.022,arXiv:0903.5540.

[14] X.Liu,ThehiddencharmdecayofY(4140)bythe rescatteringmechanism, Phys.Lett.B680(2009)137,http://dx.doi.org/10.1016/j.physletb.2009.08.049, arXiv:0904.0136.

[15] G.-J. Ding,PossiblemolecularstatesofD∗sD∗s systemandY(4140),Eur.Phys.

J. C64 (2009)297, http://dx.doi.org/10.1140/epjc/s10052-009-1146-4,arXiv: 0904.1782.

[16] J.-R.Zhang,M.-Q.Huang,(Qs¯)(∗)_{( ¯Q s)}(∗)_{molecularstatesfromQCDsumrules:}

aview on Y(4140),J. Phys. G37 (2010)025005, http://dx.doi.org/10.1088/ 0954-3899/37/2/025005,arXiv:0905.4178.

[17] Z.-G. Wang, Analysis of the Y(4140) with QCD sum rules, Eur. Phys. J. C 63 (2009) 115, http://dx.doi.org/10.1140/epjc/s10052-009-1097-9, arXiv: 0903.5200.

[18] R.Molina,E.Oset,TheY(3940),Z(3930)andtheX(4160)asdynamically gen-eratedresonancesfromthevector–vectorinteraction,Phys.Rev.D80(2009),

http://dx.doi.org/10.1103/PhysRevD.80.114013,114013,arXiv:0907.3043. [19]T.V.Uglov, Recentresults from Belle,in: Proceedings of16th International

SeminaronHighEnergyPhysics,QUARKS2010,Kolomna,Russia,2011,arXiv: 1011.3369.

[20] C.P.Shen,etal.,BelleCollaboration,Evidenceforanewresonanceandsearch fortheY(4140)inγ γ→ φJ/ψ,Phys.Rev.Lett.104(2010),http://dx.doi.org/ 10.1103/PhysRevLett.104.112004,112004,arXiv:0912.2383.

[21] LHCbCollaboration,Search for theX(4140)state inB+→J/ψφK+ decays, Phys.Rev.D85(2012),http://dx.doi.org/10.1103/PhysRevD.85.091103,091103, arXiv:1202.5087.

[22] CMS Collaboration, Absolute calibration ofthe luminosity measurement at CMS: Winter 2012 update,CMS PhysicsAnalysis Summary, CMS-PAS-SMP-12-008,2012http://cdsweb.cern.ch/record/1434360.

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

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

[25] D.J.Lange,TheEvtGenparticledecaysimulationpackage,Nucl.Instrum. Meth-odsA462(2001)152,http://dx.doi.org/10.1016/S0168-9002(01)00089-4. [26] S. Agostinelli, et al., GEANT4 Collaboration, Geant4—a simulation toolkit,

Nucl. Instrum. Methods 506 (2003) 250, http://dx.doi.org/10.1016/S0168-9002(03)01368-8.

[27] J.Beringer,etal.,ParticleDataGroup,Reviewofparticlephysics,Phys.Rev.D 86(2012)010001,http://dx.doi.org/10.1103/PhysRevD.86.010001.

[28] CMS Collaboration,CMStrackingperformance results fromearlyLHC oper-ation, Eur.Phys. J. C70(2010) 1165, http://dx.doi.org/10.1140/epjc/s10052-010-1491-3,arXiv:1007.1988.

[29] C. Daum, et al., ACCMOR Collaboration, Diffractive production of strange mesonsat63 GeV,Nucl.Phys.B187(1981)1, http://dx.doi.org/10.1016/0550-3213(81)90114-0.

[30] T.Armstrong,etal.,Bari–Birmingham–CERN–Milan–Paris–PaviaCollaboration, A partial-waveanalysisofthe Kφ systemproducedinthe reactionK−p→ K+K−K−p at18.5GeV/c,Nucl.Phys.B221(1983)1,http://dx.doi.org/10.1016/ 0550-3213(83)90616-8.

[31] D. Aston, et al., Evidence for two JP _{= 2}− _{strange meson states in the}

K2(1770)region,Phys.Lett.B308(1993)186, http://dx.doi.org/10.1016/0370-2693(93)90620-W.

[32] M. Pivk, F.R. Le, Diberder, splot: A statistical tool to unfold data distri-butions, Nucl. Instrum. Methods555 (2005) 356, http://dx.doi.org/10.1016/ j.nima.2005.08.106,arXiv:physics/0402083.

CMSCollaboration

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

Yerevan Physics Institute, Yerevan, Armenia

W. Adam, T. Bergauer, M. Dragicevic,J. Erö,C. Fabjan1,M. Friedl,R. Frühwirth1, V.M. Ghete,

N. Hörmann, J. Hrubec, M. Jeitler1,W. Kiesenhofer, V. Knünz,M. Krammer1, I. Krätschmer,D. Liko, I. Mikulec,D. Rabady2, B. Rahbaran,C. Rohringer, H. Rohringer, R. Schöfbeck, J. Strauss, A. Taurok, W. Treberer-Treberspurg,W. Waltenberger, C.-E. Wulz1

Institut für Hochenergiephysik der OeAW, Wien, Austria

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

National Centre for Particle and High Energy Physics, Minsk, Belarus

S. Alderweireldt, M. Bansal, S. Bansal,T. Cornelis, E.A. De Wolf,X. Janssen,A. Knutsson, S. Luyckx, L. Mucibello,S. Ochesanu, B. Roland,R. Rougny, Z. Staykova, H. Van Haevermaet,P. Van Mechelen, N. Van Remortel,A. Van Spilbeeck

Universiteit Antwerpen, Antwerpen, Belgium

F. Blekman, S. Blyweert,J. D’Hondt, A. Kalogeropoulos,J. Keaveney, M. Maes, A. Olbrechts, S. Tavernier, W. Van Doninck, P. Van Mulders,G.P. Van Onsem, I. Villella

Vrije Universiteit Brussel, Brussel, Belgium

B. Clerbaux, G. De Lentdecker, L. Favart, A.P.R. Gay, T. Hreus, A. Léonard,P.E. Marage, A. Mohammadi, L. Perniè, T. Reis,T. Seva, L. Thomas, C. Vander Velde, P. Vanlaer, J. Wang

Université Libre de Bruxelles, Bruxelles, Belgium

V. Adler,K. Beernaert, L. Benucci, A. Cimmino,S. Costantini, S. Dildick,G. Garcia,B. Klein, J. Lellouch, A. Marinov,J. Mccartin, A.A. Ocampo Rios, D. Ryckbosch, M. Sigamani,N. Strobbe, F. Thyssen, M. Tytgat, S. Walsh,E. Yazgan, N. Zaganidis

Ghent University, Ghent, Belgium

S. Basegmez, C. Beluffi3, G. Bruno,R. Castello, A. Caudron, L. Ceard, C. Delaere, T. du Pree,D. Favart, L. Forthomme,A. Giammanco4,J. Hollar, P. Jez, V. Lemaitre, J. Liao,O. Militaru, C. Nuttens, D. Pagano, A. Pin, K. Piotrzkowski,A. Popov5, M. Selvaggi,J.M. Vizan Garcia

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

Université de Mons, Mons, Belgium

G.A. Alves,M. Correa Martins Junior, T. Martins,M.E. Pol, M.H.G. Souza

Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil

W.L. Aldá Júnior, W. Carvalho, J. Chinellato6,A. Custódio, E.M. Da Costa, D. De Jesus Damiao,

C. De Oliveira Martins, S. Fonseca De Souza, H. Malbouisson, M. Malek,D. Matos Figueiredo, L. Mundim, H. Nogima,W.L. Prado Da Silva, A. Santoro, A. Sznajder,E.J. Tonelli Manganote6,A. Vilela Pereira

Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil

C.A. Bernardesb, F.A. Diasa,7,T.R. Fernandez Perez Tomeia, E.M. Gregoresb, C. Laganaa,F. Marinhoa, P.G. Mercadanteb,S.F. Novaesa,Sandra S. Padulaa

a_{Universidade Estadual Paulista, São Paulo, Brazil} b_{Universidade Federal do ABC, São Paulo, Brazil}

V. Genchev2, P. Iaydjiev2,S. Piperov, M. Rodozov,G. Sultanov, M. Vutova

Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria

A. Dimitrov, R. Hadjiiska,V. Kozhuharov, L. Litov,B. Pavlov, P. Petkov

University of Sofia, Sofia, Bulgaria

J.G. Bian, G.M. Chen,H.S. Chen, C.H. Jiang, D. Liang, S. Liang,X. Meng, J. Tao, J. Wang, X. Wang,Z. Wang, H. Xiao,M. Xu

Institute of High Energy Physics, Beijing, China

C. Asawatangtrakuldee, Y. Ban, Y. Guo, W. Li, S. Liu, Y. Mao,S.J. Qian, H. Teng, D. Wang,L. Zhang, W. Zou

State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China

C. Avila,C.A. Carrillo Montoya, L.F. Chaparro Sierra,J.P. Gomez, B. Gomez Moreno, J.C. Sanabria

Universidad de Los Andes, Bogota, Colombia

N. Godinovic, D. Lelas, R. Plestina8,D. Polic, I. Puljak

Technical University of Split, Split, Croatia

Z. Antunovic, M. Kovac

University of Split, Split, Croatia

V. Brigljevic,S. Duric, K. Kadija, J. Luetic, D. Mekterovic, S. Morovic, L. Tikvica

Institute Rudjer Boskovic, Zagreb, Croatia

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

University of Cyprus, Nicosia, Cyprus

M. Finger,M. Finger Jr.

Charles University, Prague, Czech Republic

A.A. Abdelalim9,Y. Assran10,S. Elgammal9, A. Ellithi Kamel11,M.A. Mahmoud12,A. Radi13,14

Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt

National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

P. Eerola,G. Fedi, M. Voutilainen

Department of Physics, University of Helsinki, 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

Helsinki Institute of Physics, Helsinki, Finland

A. Korpela,T. Tuuva

Lappeenranta University of Technology, Lappeenranta, Finland

M. Besancon,S. Choudhury, F. Couderc, M. Dejardin,D. Denegri, B. Fabbro, J.L. Faure, F. Ferri, S. Ganjour, A. Givernaud, P. Gras, G. Hamel de Monchenault∗,P. Jarry, E. Locci,J. Malcles,L. Millischer, A. Nayak, J. Rander,A. Rosowsky, M. Titov

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

S. Baffioni,F. Beaudette, L. Benhabib, L. Bianchini, M. Bluj15,P. Busson, C. Charlot,N. Daci,T. Dahms, M. Dalchenko,L. Dobrzynski, A. Florent, R. Granier de Cassagnac,M. Haguenauer, P. Miné,C. Mironov, I.N. Naranjo,M. Nguyen, C. Ochando, P. Paganini, D. Sabes,R. Salerno, Y. Sirois, C. Veelken, A. Zabi

Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France

J.-L. Agram16,J. Andrea, D. Bloch,D. Bodin, J.-M. Brom,E.C. Chabert, C. Collard,E. Conte16, F. Drouhin16, J.-C. Fontaine16,D. Gelé, U. Goerlach,C. Goetzmann, P. Juillot, A.-C. Le Bihan, P. Van Hove

Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France

S. Gadrat

Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France

S. Beauceron,N. Beaupere, G. Boudoul,S. Brochet, J. Chasserat, R. Chierici,D. Contardo, P. Depasse, H. El Mamouni,J. Fay, S. Gascon, M. Gouzevitch, B. Ille, T. Kurca, M. Lethuillier, L. Mirabito,S. Perries, L. Sgandurra,V. Sordini, Y. Tschudi,M. Vander Donckt, P. Verdier, S. Viret

Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France

Z. Tsamalaidze17

Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia

C. Autermann,S. Beranek, B. Calpas,M. Edelhoff, L. Feld, N. Heracleous,O. Hindrichs, K. Klein, A. Ostapchuk,A. Perieanu, F. Raupach, J. Sammet, S. Schael, D. Sprenger, H. Weber, B. Wittmer, V. Zhukov5

RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany

M. Ata, J. Caudron,E. Dietz-Laursonn, D. Duchardt, M. Erdmann,R. Fischer,A. Güth, T. Hebbeker, C. Heidemann,K. Hoepfner,D. Klingebiel, P. Kreuzer,M. Merschmeyer, A. Meyer,M. Olschewski, K. Padeken,P. Papacz, H. Pieta,H. Reithler, S.A. Schmitz,L. Sonnenschein, J. Steggemann, D. Teyssier, S. Thüer, M. Weber

RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany

V. Cherepanov, Y. Erdogan,G. Flügge, H. Geenen, M. Geisler, W. Haj Ahmad, F. Hoehle,B. Kargoll, T. Kress,Y. Kuessel, J. Lingemann2,A. Nowack, I.M. Nugent,L. Perchalla, O. Pooth, A. Stahl

M. Aldaya Martin,I. Asin, N. Bartosik, J. Behr, W. Behrenhoff, U. Behrens,M. Bergholz18,A. Bethani, K. Borras, A. Burgmeier,A. Cakir, L. Calligaris,A. Campbell, F. Costanza,C. Diez Pardos, S. Dooling, T. Dorland,G. Eckerlin, D. Eckstein, G. Flucke, A. Geiser, I. Glushkov,P. Gunnellini, S. Habib,J. Hauk, G. Hellwig,H. Jung, M. Kasemann, P. Katsas, C. Kleinwort,H. Kluge, M. Krämer,D. Krücker,

E. Kuznetsova, W. Lange, J. Leonard,K. Lipka, W. Lohmann18,B. Lutz, R. Mankel, I. Marfin, I.-A. Melzer-Pellmann,A.B. Meyer, J. Mnich, A. Mussgiller,S. Naumann-Emme, O. Novgorodova, F. Nowak,J. Olzem, H. Perrey, A. Petrukhin,D. Pitzl, R. Placakyte, A. Raspereza,P.M. Ribeiro Cipriano, C. Riedl, E. Ron,M.Ö. Sahin, J. Salfeld-Nebgen,R. Schmidt18, T. Schoerner-Sadenius,N. Sen, M. Stein, R. Walsh, C. Wissing

Deutsches Elektronen-Synchrotron, Hamburg, Germany

V. Blobel, H. Enderle,J. Erfle, U. Gebbert,M. Görner, M. Gosselink, J. Haller, K. Heine, R.S. Höing, G. Kaussen, H. Kirschenmann,R. Klanner, R. Kogler, J. Lange,I. Marchesini, T. Peiffer, N. Pietsch, D. Rathjens, C. Sander, H. Schettler,P. Schleper, E. Schlieckau, A. Schmidt, M. Schröder, T. Schum, M. Seidel,J. Sibille19, V. Sola, H. Stadie,G. Steinbrück, J. Thomsen, D. Troendle,L. Vanelderen

University of Hamburg, Hamburg, Germany

C. Barth,C. Baus, J. Berger,C. Böser, T. Chwalek, W. De Boer, A. Descroix, A. Dierlamm,M. Feindt, M. Guthoff2,F. Hartmann2,T. Hauth2, H. Held, K.H. Hoffmann,U. Husemann, I. Katkov5,

J.R. Komaragiri, A. Kornmayer2,P. Lobelle Pardo, D. Martschei, Th. Müller, M. Niegel, A. Nürnberg, O. Oberst,J. Ott, G. Quast, K. Rabbertz,F. Ratnikov,S. Röcker, F.-P. Schilling, G. Schott, H.J. Simonis, F.M. Stober,R. Ulrich, J. Wagner-Kuhr, S. Wayand, T. Weiler, M. Zeise

Institut für Experimentelle Kernphysik, Karlsruhe, Germany

G. Anagnostou, G. Daskalakis,T. Geralis,S. Kesisoglou, A. Kyriakis, D. Loukas, A. Markou, C. Markou, E. Ntomari

Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece

L. Gouskos,T.J. Mertzimekis,A. Panagiotou, N. Saoulidou, E. Stiliaris

University of Athens, Athens, Greece

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

University of Ioánnina, Ioánnina, Greece

G. Bencze,C. Hajdu, P. Hidas, D. Horvath20, B. Radics,F. Sikler, V. Veszpremi, G. Vesztergombi21, A.J. Zsigmond

KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary

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

Institute of Nuclear Research ATOMKI, Debrecen, Hungary

J. Karancsi, P. Raics, Z.L. Trocsanyi,B. Ujvari

University of Debrecen, Debrecen, Hungary

S.K. Swain22

National Institute of Science Education and Research, Bhubaneswar, India

S.B. Beri, V. Bhatnagar,N. Dhingra, R. Gupta, M. Kaur, M.Z. Mehta, M. Mittal, N. Nishu, L.K. Saini, A. Sharma,J.B. Singh

Ashok Kumar,Arun Kumar, S. Ahuja,A. Bhardwaj, B.C. Choudhary,S. Malhotra, M. Naimuddin,K. Ranjan, P. Saxena,V. Sharma, R.K. Shivpuri

University of Delhi, 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, A.P. Singh

Saha Institute of Nuclear Physics, Kolkata, India

A. Abdulsalam,D. Dutta, S. Kailas,V. Kumar, A.K. Mohanty2,L.M. Pant, P. Shukla, A. Topkar

Bhabha Atomic Research Centre, Mumbai, India

T. Aziz,R.M. Chatterjee, S. Ganguly,S. Ghosh, M. Guchait23,A. Gurtu24,G. Kole, S. Kumar, M. Maity25, G. Majumder,K. Mazumdar, G.B. Mohanty, B. Parida,K. Sudhakar, N. Wickramage26

Tata Institute of Fundamental Research – EHEP, Mumbai, India

S. Banerjee, S. Dugad

Tata Institute of Fundamental Research – HECR, Mumbai, India

H. Arfaei27,H. Bakhshiansohi, S.M. Etesami28,A. Fahim27,H. Hesari, A. Jafari,M. Khakzad, M. Mohammadi Najafabadi,S. Paktinat Mehdiabadi, B. Safarzadeh29,M. Zeinali

Institute for Research in Fundamental Sciences (IPM), Tehran, Iran

M. Grunewald

University College Dublin, Dublin, Ireland

M. Abbresciaa,b, L. Barbonea,b,C. Calabriaa,b,S.S. Chhibraa,b,A. Colaleoa,D. Creanzaa,c,

N. De Filippisa,c, M. De Palmaa,b, L. Fiorea, G. Iasellia,c, G. Maggia,c, M. Maggia,B. Marangellia,b,

S. Mya,c,S. Nuzzoa,b, N. Pacificoa, A. Pompilia,b,G. Pugliesea,c, G. Selvaggia,b,L. Silvestrisa, G. Singha,b, R. Vendittia,b, P. Verwilligena,G. Zitoa

a_{INFN Sezione di Bari, Bari, Italy} b_{Università di Bari, Bari, Italy} c_{Politecnico di Bari, Bari, Italy}

G. Abbiendia,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,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,2, M. Meneghellia,b,A. Montanaria, F.L. Navarriaa,b,F. Odoricia,A. Perrottaa, F. Primaveraa,b,

A.M. Rossia,b,T. Rovellia,b, G.P. Sirolia,b,N. Tosia,b, R. Travaglinia,b

a_{INFN Sezione di Bologna, Bologna, Italy} b_{Università di Bologna, Bologna, Italy}

S. Albergoa,b, M. Chiorbolia,b, S. Costaa,b, F. Giordanoa,2, R. Potenzaa,b, A. Tricomia,b, C. Tuvea,b

a_{INFN Sezione di Catania, Catania, Italy} b_{Università di Catania, Catania, Italy}

G. Barbaglia,V. Ciullia,b,C. Civininia, R. D’Alessandroa,b, E. Focardia,b,S. Frosalia,b,E. Galloa, S. Gonzia,b, V. Goria,b, P. Lenzia,b, M. Meschinia, S. Paolettia, G. Sguazzonia,A. Tropianoa,b

a_{INFN Sezione di Firenze, Firenze,}

Italy

b_{Università di Firenze, Firenze, Italy}

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

P. Fabbricatorea, R. Musenicha,S. Tosia,b

a_{INFN Sezione di Genova, Genova, Italy} b_{Università di Genova, Genova, Italy}

A. Benagliaa, F. De Guioa,b, L. Di Matteoa,b, S. Fiorendia,b,S. Gennaia,A. Ghezzia,b, P. Govonia,b, M.T. Lucchinia,b,2,S. Malvezzia,R.A. Manzonia,b,2, A. Martellia,b,2,D. Menascea,L. Moronia, M. Paganonia,b,D. Pedrinia,S. Ragazzia,b, N. Redaellia,T. Tabarelli de Fatisa,b

a_{INFN Sezione di Milano-Bicocca, Milano, Italy} b_{Università di Milano-Bicocca, Milano, Italy}

S. Buontempoa, N. Cavalloa,c, A. De Cosaa,b,F. Fabozzia,c, A.O.M. Iorioa,b,L. Listaa, S. Meolaa,d,2, M. Merolaa, P. Paoluccia,2

a_{INFN Sezione di Napoli, Napoli, Italy} b_{Università di Napoli ‘Federico II’, Napoli, Italy} c_{Università della Basilicata (Potenza), Napoli, Italy} d_{Università G. Marconi (Roma), Napoli, Italy}

P. Azzia,N. Bacchettaa,M. Bellatoa,D. Biselloa,b, A. Brancaa,b,R. Carlina,b, P. Checchiaa, T. Dorigoa, M. Galantia,b,2, F. Gasparinia,b, U. Gasparinia,b, P. Giubilatoa,b,F. Gonellaa, A. Gozzelinoa,

K. Kanishcheva,c,S. Lacapraraa,I. Lazzizzeraa,c,M. Margonia,b,A.T. Meneguzzoa,b, F. Montecassianoa, J. Pazzinia,b, N. Pozzobona,b,P. Ronchesea,b, F. Simonettoa,b,E. Torassaa, M. Tosia,b,S. Vaninia,b, P. Zottoa,b, A. Zucchettaa,b,G. Zumerlea,b

a_{INFN Sezione di Padova, Padova, Italy} b_{Università di Padova, Padova, Italy} c_{Università di Trento (Trento), Padova, Italy}

M. Gabusia,b, S.P. Rattia,b,C. Riccardia,b,P. Vituloa,b

a_{INFN Sezione di Pavia, Pavia, Italy} b_{Università di Pavia, Pavia, Italy}

M. Biasinia,b, G.M. Bileia,L. Fanòa,b, P. Laricciaa,b, G. Mantovania,b,M. Menichellia, A. Nappia,b,†, F. Romeoa,b, A. Sahaa, A. Santocchiaa,b,A. Spieziaa,b

a_{INFN Sezione di Perugia, Perugia, Italy} b_{Università di Perugia, Perugia, Italy}

K. Androsova,30,P. Azzurria,G. Bagliesia,J. Bernardinia,T. Boccalia,G. Broccoloa,c,R. Castaldia,

R.T. D’Agnoloa,c,2,R. Dell’Orsoa,F. Fioria,c,L. Foàa,c, A. Giassia,M.T. Grippoa,30,A. Kraana,F. Ligabuea,c, T. Lomtadzea, L. Martinia,30,A. Messineoa,b,F. Pallaa,A. Rizzia,b,A.T. Serbana,P. Spagnoloa,

P. Squillaciotia,R. Tenchinia, G. Tonellia,b,A. Venturia, P.G. Verdinia, C. Vernieria,c

a_{INFN Sezione di Pisa, Pisa, Italy} b_{Università di Pisa, Pisa, Italy}

c_{Scuola Normale Superiore di Pisa, Pisa, Italy}

L. Baronea,b,F. Cavallaria, D. Del Rea,b,M. Diemoza, M. Grassia,b,2, E. Longoa,b, F. Margarolia,b, P. Meridiania,F. Michelia,b,S. Nourbakhsha,b, G. Organtinia,b, R. Paramattia,S. Rahatloua,b,L. Soffia,b

a_{INFN Sezione di Roma, Roma, Italy} b_{Università di Roma, Roma, Italy}

N. Amapanea,b, R. Arcidiaconoa,c,S. Argiroa,b,M. Arneodoa,c,C. Biinoa,N. Cartigliaa,S. Casassoa,b, M. Costaa,b,N. Demariaa, C. Mariottia, S. Masellia, E. Migliorea,b,V. Monacoa,b,M. Musicha,

M.M. Obertinoa,c,G. Ortonaa,b, N. Pastronea,M. Pelliccionia,2, A. Potenzaa,b,A. Romeroa,b, M. Ruspaa,c, R. Sacchia,b, A. Solanoa,b, A. Staianoa, U. Tamponia

a_{INFN Sezione di Torino, Torino, Italy} b_{Università di Torino, Torino, Italy}

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

a_{INFN Sezione di Trieste, Trieste, Italy} b_{Università di Trieste, Trieste, Italy}

S. Chang,T.Y. Kim, S.K. Nam

Kangwon National University, Chunchon, Republic of Korea

D.H. Kim,G.N. Kim, J.E. Kim, D.J. Kong,Y.D. Oh, H. Park, D.C. Son

Kyungpook National University, Daegu, Republic of Korea

J.Y. Kim,Zero J. Kim, S. Song

Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Republic of Korea

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

Korea University, Seoul, Republic of Korea

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

University of Seoul, Seoul, Republic of Korea

Y. Choi,Y.K. Choi,J. Goh, M.S. Kim, E. Kwon, B. Lee, J. Lee,S. Lee, H. Seo,I. Yu

Sungkyunkwan University, Suwon, Republic of Korea

I. Grigelionis,A. Juodagalvis

Vilnius University, Vilnius, Lithuania

H. Castilla-Valdez,E. De La Cruz-Burelo, I. Heredia-de La Cruz31,R. Lopez-Fernandez, J. Martínez-Ortega, A. Sanchez-Hernandez,L.M. Villasenor-Cendejas

Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico

S. Carrillo Moreno, F. Vazquez Valencia

Universidad Iberoamericana, Mexico City, Mexico

H.A. Salazar Ibarguen

Benemerita Universidad Autonoma de Puebla, Puebla, Mexico

E. Casimiro Linares, A. Morelos Pineda, M.A. Reyes-Santos

Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico

D. Krofcheck

University of Auckland, Auckland, New Zealand

A.J. Bell,P.H. Butler, R. Doesburg, S. Reucroft, H. Silverwood

University of Canterbury, Christchurch, New Zealand

M. Ahmad, M.I. Asghar,J. Butt, H.R. Hoorani, S. Khalid, W.A. Khan, T. Khurshid, S. Qazi,M.A. Shah, M. Shoaib

National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan

H. Bialkowska,B. Boimska, T. Frueboes,M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper,G. Wrochna, P. Zalewski

National Centre for Nuclear Research, Swierk, Poland

G. Brona, K. Bunkowski, M. Cwiok,W. Dominik, K. Doroba, A. Kalinowski, M. Konecki,J. Krolikowski, M. Misiura, W. Wolszczak

Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland

N. Almeida, P. Bargassa, A. David,P. Faccioli, P.G. Ferreira Parracho,M. Gallinaro, J. Rodrigues Antunes, J. Seixas2, J. Varela, P. Vischia

Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal

S. Afanasiev,P. Bunin, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, V. Konoplyanikov,G. Kozlov, A. Lanev,A. Malakhov,V. Matveev, P. Moisenz, V. Palichik, V. Perelygin, S. Shmatov, N. Skatchkov, V. Smirnov, A. Zarubin

Joint Institute for Nuclear Research, Dubna, Russia

S. Evstyukhin,V. Golovtsov, Y. Ivanov, V. Kim, P. Levchenko,V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev,An. Vorobyev

Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia

Yu. Andreev,A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov,N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin

Institute for Nuclear Research, Moscow, Russia

V. Epshteyn, M. Erofeeva, V. Gavrilov, N. Lychkovskaya,V. Popov, G. Safronov, S. Semenov, A. Spiridonov, V. Stolin, E. Vlasov, A. Zhokin

Institute for Theoretical and Experimental Physics, Moscow, Russia

V. Andreev,M. Azarkin, I. Dremin, M. Kirakosyan, A. Leonidov, G. Mesyats, S.V. Rusakov,A. Vinogradov

P.N. Lebedev Physical Institute, Moscow, Russia

A. Belyaev,E. Boos, M. Dubinin7, L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova,I. Lokhtin, A. Markina,S. Obraztsov, S. Petrushanko,V. Savrin, A. Snigirev

Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 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

State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia

P. Adzic32, M. Djordjevic,M. Ekmedzic, D. Krpic32,J. Milosevic

University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia

M. Aguilar-Benitez,J. Alcaraz Maestre, C. Battilana,E. Calvo, M. Cerrada,M. Chamizo Llatas2,N. Colino, B. De La Cruz,A. Delgado Peris,D. Domínguez Vázquez, C. Fernandez Bedoya,J.P. Fernández Ramos, A. Ferrando, J. Flix, M.C. Fouz,P. Garcia-Abia, O. Gonzalez Lopez,S. Goy Lopez, J.M. Hernandez, M.I. Josa, G. Merino, E. Navarro De Martino,J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo,L. Romero,

J. Santaolalla, M.S. Soares, C. Willmott

Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain

C. Albajar, J.F. de Trocóniz

H. Brun, J. Cuevas,J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero,L. Lloret Iglesias, J. Piedra Gomez

Universidad de Oviedo, Oviedo, Spain

J.A. Brochero Cifuentes,I.J. Cabrillo, A. Calderon, S.H. Chuang, J. Duarte Campderros, M. Fernandez, G. Gomez, J. Gonzalez Sanchez, A. Graziano,C. Jorda, A. Lopez Virto,J. Marco, R. Marco,

C. Martinez Rivero,F. Matorras, F.J. Munoz Sanchez,T. Rodrigo, A.Y. Rodríguez-Marrero,A. Ruiz-Jimeno, L. Scodellaro,I. Vila, R. Vilar Cortabitarte

Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain

D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis,P. Baillon, A.H. Ball, D. Barney, J. Bendavid,J.F. Benitez, C. Bernet8, G. Bianchi, P. Bloch,A. Bocci, A. Bonato,O. Bondu, C. Botta, H. Breuker,T. Camporesi, G. Cerminara, T. Christiansen,J.A. Coarasa Perez, S. Colafranceschi33,D. d’Enterria, A. Dabrowski, A. De Roeck, S. De Visscher, S. Di Guida, M. Dobson, N. Dupont-Sagorin,A. Elliott-Peisert, J. Eugster, W. Funk, G. Georgiou, M. Giffels,D. Gigi,K. Gill, D. Giordano, M. Girone, M. Giunta,F. Glege,

R. Gomez-Reino Garrido,S. Gowdy, R. Guida, J. Hammer, M. Hansen,P. Harris, C. Hartl,A. Hinzmann, V. Innocente, P. Janot, E. Karavakis,K. Kousouris,K. Krajczar, P. Lecoq,Y.-J. Lee, C. Lourenço,N. Magini, M. Malberti,L. Malgeri,M. Mannelli, L. Masetti, F. Meijers, S. Mersi,E. Meschi, L. Moneta, R. Moser, M. Mulders, P. Musella,E. Nesvold, L. Orsini, E. Palencia Cortezon,E. Perez,L. Perrozzi, A. Petrilli, A. Pfeiffer,M. Pierini,M. Pimiä, D. Piparo, M. Plagge, G. Polese, L. Quertenmont,A. Racz, W. Reece, G. Rolandi34,C. Rovelli35, M. Rovere, H. Sakulin, F. Santanastasio,C. Schäfer, C. Schwick,I. Segoni, S. Sekmen,A. Sharma,P. Siegrist, P. Silva,M. Simon, P. Sphicas36,D. Spiga, M. Stoye, A. Tsirou, G.I. Veres21,J.R. Vlimant, H.K. Wöhri, S.D. Worm37,W.D. Zeuner

CERN, European Organization for Nuclear Research, Geneva, Switzerland

W. Bertl,K. Deiters,W. Erdmann, K. Gabathuler,R. Horisberger, Q. Ingram, H.C. Kaestli, S. König, D. Kotlinski,U. Langenegger, D. Renker, T. Rohe

Paul Scherrer Institut, Villigen, Switzerland

F. Bachmair, L. Bäni, P. Bortignon, M.A. Buchmann,B. Casal, N. Chanon, A. Deisher, G. Dissertori,

M. Dittmar, M. Donegà, M. Dünser, P. Eller,K. Freudenreich, C. Grab, D. Hits, P. Lecomte, W. Lustermann, A.C. Marini,P. Martinez Ruiz del Arbol, N. Mohr,F. Moortgat, C. Nägeli38,P. Nef, F. Nessi-Tedaldi,

F. Pandolfi,L. Pape, F. Pauss,M. Peruzzi, F.J. Ronga,M. Rossini,L. Sala, A.K. Sanchez, A. Starodumov39, B. Stieger,M. Takahashi, L. Tauscher†, A. Thea, K. Theofilatos,D. Treille, C. Urscheler, R. Wallny, H.A. Weber

Institute for Particle Physics, ETH Zurich, Zurich, Switzerland

C. Amsler40,V. Chiochia, C. Favaro,M. Ivova Rikova, B. Kilminster, B. Millan Mejias, P. Otiougova, P. Robmann, H. Snoek,S. Taroni, S. Tupputi,M. Verzetti

Universität Zürich, Zurich, Switzerland

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

National Central University, Chung-Li, Taiwan

P. Bartalini,P. Chang, Y.H. Chang, Y.W. Chang,Y. Chao, K.F. Chen, C. Dietz, U. Grundler,W.-S. Hou, Y. Hsiung, K.Y. Kao,Y.J. Lei, R.-S. Lu,D. Majumder, E. Petrakou,X. Shi, J.G. Shiu, Y.M. Tzeng,M. Wang

National Taiwan University (NTU), Taipei, Taiwan

B. Asavapibhop,N. Suwonjandee

A. Adiguzel, M.N. Bakirci41, S. Cerci42,C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut, E. Gurpinar,I. Hos, E.E. Kangal, A. Kayis Topaksu,G. Onengut43,K. Ozdemir, S. Ozturk41, A. Polatoz, K. Sogut44,D. Sunar Cerci42,B. Tali42,H. Topakli41,M. Vergili

Cukurova University, Adana, Turkey

I.V. Akin, T. Aliev,B. Bilin, S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Guler,G. Karapinar45,K. Ocalan, A. Ozpineci,M. Serin, R. Sever,U.E. Surat, M. Yalvac, M. Zeyrek

Middle East Technical University, Physics Department, Ankara, Turkey

E. Gülmez,B. Isildak46,M. Kaya47,O. Kaya47,S. Ozkorucuklu48,N. Sonmez49

Bogazici University, Istanbul, Turkey

H. Bahtiyar50,E. Barlas, K. Cankocak, Y.O. Günaydin51,F.I. Vardarlı, M. Yücel

Istanbul Technical University, Istanbul, Turkey

L. Levchuk,P. Sorokin

National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine

J.J. Brooke,E. Clement, D. Cussans, H. Flacher,R. Frazier, J. Goldstein,M. Grimes, G.P. Heath, H.F. Heath, L. Kreczko, S. Metson,D.M. Newbold37,K. Nirunpong, A. Poll, S. Senkin, V.J. Smith,T. Williams

University of Bristol, Bristol, United Kingdom

L. Basso52,K.W. Bell, A. Belyaev52,C. Brew, R.M. Brown, D.J.A. Cockerill, J.A. Coughlan, K. Harder,

S. Harper, J. Jackson, E. Olaiya,D. Petyt, B.C. Radburn-Smith, C.H. Shepherd-Themistocleous, I.R. Tomalin, W.J. Womersley

Rutherford Appleton Laboratory, Didcot, United Kingdom

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

M. Della Negra, W. Ferguson,J. Fulcher, D. Futyan, A. Gilbert,A. Guneratne Bryer, G. Hall,Z. Hatherell, J. Hays, G. Iles, M. Jarvis, G. Karapostoli, M. Kenzie,R. Lane, R. Lucas37,L. Lyons, A.-M. Magnan,

J. Marrouche, B. Mathias,R. Nandi, J. Nash, A. Nikitenko39,J. Pela, M. Pesaresi, K. Petridis,M. Pioppi53, D.M. Raymond, S. Rogerson,A. Rose, C. Seez,P. Sharp†,A. Sparrow, A. Tapper, M. Vazquez Acosta, T. Virdee,S. Wakefield, N. Wardle,T. Whyntie

Imperial College, London, United Kingdom

M. Chadwick, J.E. Cole, P.R. Hobson, A. Khan,P. Kyberd, D. Leggat,D. Leslie, W. Martin,I.D. Reid, P. Symonds, L. Teodorescu, M. Turner

Brunel University, Uxbridge, United Kingdom

J. Dittmann, K. Hatakeyama,A. Kasmi, H. Liu, T. Scarborough

Baylor University, Waco, USA

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

The University of Alabama, Tuscaloosa, USA

A. Avetisyan, T. Bose,C. Fantasia, A. Heister, P. Lawson, D. Lazic, J. Rohlf, D. Sperka, J. St. John,L. Sulak

Boston University, Boston, USA

J. Alimena,S. Bhattacharya, G. Christopher,D. Cutts, Z. Demiragli,A. Ferapontov, A. Garabedian,

U. Heintz, S. Jabeen, G. Kukartsev, E. Laird,G. Landsberg, M. Luk, M. Narain, M. Segala, T. Sinthuprasith, T. Speer