Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs

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Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Constraints

on

the

Higgs

boson

width

from

off-shell

production

and

decay

to

Z-boson

pairs

.CMSCollaboration CERN,Switzerland

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

Articlehistory: Received14May2014

Receivedinrevisedform12June2014 Accepted30June2014

Availableonline3July2014 Editor: M.Doser Keywords: CMS Physics Higgs Diboson Properties

ConstraintsarepresentedonthetotalwidthoftherecentlydiscoveredHiggsboson,ΓH,usingitsrelative on-shell and off-shell production and decay rates to apair of Z bosons, where one Z boson decays to an electron ormuon pair,and the other to an electron, muon,or neutrino pair. The analysis is based onthe data collectedbythe CMS experiment atthe LHCin 2011and 2012, corresponding to integratedluminositiesof5.1 fb−1atacenter-of-massenergy√s=7 TeV and19.7 fb−1at√s=8 TeV. Asimultaneousmaximumlikelihoodﬁttothemeasuredkinematicdistributionsneartheresonancepeak and abovetheZ-bosonpairproductionthresholdleadstoanupperlimitontheHiggsbosonwidthof ΓH<22 MeV ata95%conﬁdencelevel,whichis5.4timestheexpectedvalueinthestandardmodelat themeasuredmassof mH=125.6 GeV.

The discovery of a new boson consistent with the standard model (SM) Higgs boson by the ATLAS and CMS Collaborations wasrecentlyreported[1–3].Themassofthenewboson(mH)was measuredtobenear125 GeV,andthespin-paritypropertieswere furtherstudiedbybothexperiments,favoring thescalar,JPC₌₀++_, hypothesis [4–7].The measurements werefound tobe consistent withasinglenarrowresonance,andanupperlimitof3.4 GeV ata 95%conﬁdencelevel(CL)onitsdecaywidth(ΓH)wasreportedby theCMSexperimentinthefour-leptondecaychannel[7].Adirect width measurement at the resonance peak is limitedby experi-mental resolution,and is onlysensitive to valuesfar larger than theexpectedwidthofaround4 MeV fortheSMHiggsboson[8,9]. It was recently proposed [10] to constrain the Higgs boson width using its off-shell production and decay to two Z bosons awayfromtheresonancepeak[11].Inthedominantgluonfusion productionmode the off-shellproduction cross section isknown tobe sizable.Thisarisesfroman enhancement inthedecay am-plitudefromthevicinityoftheZ-bosonpairproductionthreshold. A further enhancement comes, in gluon fusion production, from the top-quarkpair productionthreshold. The zero-width approx-imationis inadequate andthe ratioof the off-shellcross section above2mZtotheon-shellsignalisoftheorderof8%[11,12]. Fur-therdevelopmentstothemeasurementoftheHiggsbosonwidth wereproposedinRefs.[13,14].

_E-mail_address:_{cms-publication-committee-chair@cern.ch}_.

The gluon fusion production cross section depends on ΓH throughtheHiggsbosonpropagator

dσgg→H→ZZ dm2_ZZ ∼ g2 ggHgHZZ2 (m2_ZZ−m2_H)2₊_m2 HΓH2 , (1)

where gggH and gHZZ are the couplings of the Higgs boson to gluonsandZbosons,respectively.Integratingeitherinasmall re-gion around mH,or above themass thresholdmZZ>2mZ,where

(mZZ−mH) ΓH,thecrosssectionsare,respectively, σ_ggon-shell_→_H_→_ZZ∗∼ g2 ggHgHZZ2 mHΓH andσ_ggoff-shell_→_H∗_→ZZ∼ g2 ggHg2HZZ (2mZ)2 . (2)

FromEq.(2),itisclearthatameasurementoftherelativeoff-shell andon-shellproductionintheH→ZZ channelprovidesdirect in-formationon ΓH,aslongasthecouplingratiosremainunchanged, i.e. the gluon fusion production is dominated by the top-quark loopandtherearenonewparticlescontributing.Inparticular,the on-shell production crosssection is unchanged undera common scaling ofthe squared product of the couplings and of the total width ΓH, while the off-shell production cross section increases linearlywiththisscalingfactor.

The dominant contribution for the production of a pair of Z bosons comesfromthequark-initiatedprocess, qq→ZZ, the dia-gramforwhichisdisplayedinFig. 1(left).Thegluon-induced dibo-son productioninvolvesthe gg→ZZ continuumbackground pro-ductionfromtheboxdiagrams, asillustrated inFig. 1(center). An

http://dx.doi.org/10.1016/j.physletb.2014.06.077

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Fig. 1. LowestordercontributionstothemainZZ productionprocesses:(left)quark-initiatedproduction,qq→ZZ,(center)ggcontinuumbackgroundproduction,gg→ZZ, and(right)Higgs-mediatedggproduction,gg→H→ZZ,thesignal.

exampleofthesignalproductiondiagramisshowninFig. 1(right). Theinterference betweenthetwo gluon-inducedcontributions is signiﬁcantathighmZZ [15],andistakenintoaccountinthe anal-ysisoftheoff-shellsignal.

Vectorbosonfusion(VBF)production,whichcontributesatthe levelofabout7% totheon-shell crosssection, isexpectedto in-crease above 2mZ. The above formalism describing the ratio of off-shellandon-shellcrosssectionsisapplicable tothe VBF pro-duction mode. In this analysis we constrain the fraction of VBF productionusing theproperties ofthe eventsin theon-shell re-gion.TheothermainHiggsbosonproductionmechanisms,ttH and VH(V=Z, W), which contribute at the level ofabout 5% to the on-shellsignal,arenot expectedto produceasigniﬁcantoff-shell contributionasthey are suppressedat highmass [8,9]. Theyare thereforeneglectedintheoff-shellanalysis.

InthisLetter,wepresentconstraintsontheHiggsbosonwidth usingitsoff-shellproductionanddecaytoZ-bosonpairs,inthe ﬁ-nalstateswhereoneZbosondecaystoanelectronoramuonpair andtheother toeitheran electronoramuonpair,H→ZZ→4

(4 channel),orapairofneutrinos,H→ZZ→22ν (22ν chan-nel).RelyingontheobservedHiggsbosonsignal intheresonance peakregion[7],thesimultaneousmeasurementofthesignalinthe high-mass region leads to constraints on the Higgs boson width

ΓHinthe4 decaychannel. The22ν decaychannel,which ben-eﬁtsfromahigherbranchingfraction[16,17],isusedinthe high-massregiontofurtherincreasethesensitivitytotheHiggsboson width. The analysisisperformed forthe tree-levelHVVcoupling ofascalarHiggsboson,consistentwithourobservations[4,7],and implicationsfortheanomalousHVVinteractionsarediscussed.The Higgsboson mass is set to the measured value in the 4 decay channelofmH=125.6 GeV [7]andthe Higgsbosonwidthisset tothecorrespondingexpectedvalueintheSMof ΓSM

H =4.15 MeV [8,9].

Themeasurementis basedonpp collision datacollectedwith the CMS detector at the LHC in 2011, corresponding to an in-tegrated luminosity of 5.1 fb−1 at the center-of-mass energy of

√

s=7 TeV (4 channel), and in 2012, corresponding to an in-tegrated luminosity of 19.7 fb−1 at √s=8 TeV (4 and 22ν

channels). The CMS detector, described in detail elsewhere [18], providesexcellentresolutionforthemeasurementofelectronand muontransversemomenta(pT)overawiderange.Thesignal can-didatesareselectedusingwell-identiﬁedandisolatedprompt lep-tons. Theonlineselection andeventreconstruction are described elsewhere[2,3,7,16].The analysispresented hereisbased onthe sameeventselectionasusedinRefs. [7,16].

The analysis in the 4 channel uses the four-lepton invari-antmassdistribution aswell asamatrix elementlikelihood dis-criminanttoseparate theZZcomponentsoriginatingfrom gluon-and quark-initiated processes. We deﬁne the on-shell signal re-gion as105.6 <m4<140.6 GeV and the off-shell signal region

asm4>220 GeV.Theanalysisinthe22ν channelreliesonthe

transversemassdistributionmT, m2_T= pT,22+m22+ E_Tmiss2+m22 2 −pT,2+ EmissT 2 , (3)

wherepT,2andm2arethemeasuredtransversemomentumand

invariant mass of the dilepton system, respectively. The missing transverseenergy,Emiss_T ,isdeﬁnedasthemagnitudeofthe trans-versemomentumimbalanceevaluatedasthenegative ofthe vec-torialsumoftransversemomentaofallthereconstructedparticles intheevent.Inthe22ν channel,theoff-shellsignalregionis de-ﬁnedasmT>180 GeV.Thechoiceoftheoff-shellregionsinboth channels is done prior to looking at the data, based on the ex-pectedsensitivity.

Simulated Monte Carlo (MC) samples of gg→4 and gg→ 22ν events are generated at leading order (LO) in perturbative quantum chromodynamics (QCD), including theHiggs boson sig-nal, the continuum background, and the interference contribu-tionsusingrecentversionsoftwodifferentMCgenerators, gg2VV 3.1.5 [11,19] and mcfm 6.7 [20], inorder to cross-check theoret-ical inputs. The QCD renormalizationand factorizationscales are settomZZ/2 (dynamicscales)andMSTW2008LOparton distribu-tionfunctions(PDFs)[21]are used.Higher-order QCDcorrections for the gluon fusion signal process are knownto an accuracy of next-to-next-to-leading order(NNLO) and next-to-next-to-leading logarithmsforthetotalcrosssection[8,9]andtoNNLOasa func-tion ofmZZ [14]. Thesecorrection factors tothe LOcrosssection (K factors)aretypicallyintherangeof2.0to2.5.Afterthe applica-tionofthemZZ-dependentKfactors,theeventyieldisnormalized to thecross section fromRefs. [8,9]. Forthe gg→ZZ continuum background,althoughnoexactcalculationexistsbeyondLO,ithas beenrecentlyshown[22] thatthesoftcollinearapproximation is abletodescribethebackgroundcrosssectionandthereforethe in-terference termatNNLO.Following thiscalculation,we assignto theLObackgroundcrosssection(and,consequently,tothe interfer-encecontribution)aKfactorequaltothatusedforthesignal[14]. The limited theoretical knowledge of the backgroundK factor at NNLOis takenintoaccount byincludingan additionalsystematic uncertainty,theimpactofwhichonthemeasurementis neverthe-lesssmall.

Vector bosonfusion eventsare generated with phantom[23]. Off-shellandinterferenceeffectswiththenonresonantproduction areincludedatLOinthesesimulations.Theeventyieldis normal-ized tothecross sectionatNNLO QCD andnext-to-leadingorder (NLO)electroweak(EW)[8,9]accuracy,withanormalizationfactor showntobeindependentofmZZ.

In order to parameterize and validate the distributions of all thecomponentsforbothgluonfusion andVBFprocesses,speciﬁc simulatedsamplesarealsoproducedthatdescribeonlythesignal or the continuum background, as well as several scenarios with scaledcouplingsandwidth.Fortheon-shellanalysis,signalevents are generated eitherwith powheg [24–27] productionat NLO in QCD and JHUGen [28,29] decay (gluon fusion and VBF), or with pythia_6.4_[30]_(VH_and_{ttH production).}

Inboththe4and22ν channelsthedominantbackgroundis qq→ZZ.WeassumeSMproductionratesforthisbackground,the contributionof whichisevaluated by powheg simulation atNLO inQCD[31].Next-to-leadingorderEWcalculations[32,33],which predict negative and mZZ-dependent corrections to the qq→ZZ processforon-shellZ-bosonpairs,aretakenintoaccount.

Allsimulatedeventsundergopartonshoweringand hadroniza-tionusing pythia.AsisdoneinRef.[7]forLOsamples,theparton

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Fig. 2. Distributionofthe four-leptoninvariantmass inthe range100 <m4< 800 GeV.Pointsrepresentthe data,ﬁlled histogramsthe expectedcontributions fromthereducible(Z+X)andqq backgrounds,andfromthesumofthegluon fusion(gg)andvectorbosonfusion(VV)processes,includingtheHiggsboson me-diatedcontributions.Theinsetshowsthedistributioninthelowmassregionafter aselectionrequirementontheMELAlikelihooddiscriminant Dkin

bkg>0.5[7].Inthis region,thecontributionofthettH andVH productionprocessesisaddedtothe dominantgluonfusionandVBFcontributions.

showeringsettingsaretunedtoapproximatelyreproducetheZZpT spectrumpredictedatNNLO fortheHiggsbosonproduction[34]. GeneratedeventsarethenprocessedwiththedetailedCMS detec-tor simulationbased on Geant4 [35,36], andreconstructed using thesamealgorithmsasusedfortheobservedevents.

Thefinalstate inthe4 channelischaracterizedbyfour well-identifiedandisolatedleptons formingtwopairsofopposite-sign andsame-flavor leptonsconsistentwithtwoZ bosons.This chan-nelbenefitsfromaprecisereconstructionofallfinal stateleptons andfromaverylowinstrumentalbackground.Theeventselection and the reducible background evaluation are performed follow-ing themethods described in Ref.[7].Afterthe selection, the4

data sample is dominated by the quark-initiated qq→ZZ→4

(qq→4)andgg→4productions.

Fig. 2presentsthemeasuredm4distributionoverthefullmass

range,m4>100 GeV, together with the expected SM

contribu-tions. The gg→4 contribution is clearly visible inthe on-shell signalregionandattheZ-bosonpairproductionthreshold,above the qq→4 background.The observed distribution is consistent withthe expectationfromSM processes. We observe223 events in the off-shell signal region, while we expect 217.6±9.5 from SMprocesses,includingtheSMHiggsbosonsignal.

Inordertoenhance thesensitivitytotheggproductioninthe off-shellregion,alikelihooddiscriminant Dggisused,which char-acterizestheeventtopology inthe4center-of-massframe using theobservables (mZ1, mZ2, Ω) foragivenvalue ofm4,whereΩ

denotes the ﬁve angles deﬁned in Ref. [28]. The discriminant is builtfromtheprobabilities P_totgg and P_bkgqq foraneventtooriginate fromeitherthegg→4 ortheqq→4 process.Weusethe ma-trixelementlikelihoodapproach(MELA)[2,29]fortheprobability computation using the mcfm matrix elements for both gg→4

andqq→4processes.Theprobability P_totgg forthegg→4 pro-cess includes the signal (P_siggg), the background (P_bkggg), and their

Fig. 3. Distributionsof(top)the four-leptoninvariant mass afteraselection re-quirementontheMELAlikelihooddiscriminant Dgg>0.65,and(bottom)the Dgg likelihooddiscriminantform4>330 GeV inthe4channel.Pointsrepresentthe data,ﬁlledhistogramstheexpectedcontributionsfromthereducible(Z+X)and qq backgrounds,andfromthegluonfusion(gg)andvectorbosonfusion(VV)SM processes(includingtheHiggsbosonmediatedcontributions).Thedashedline cor-respondstothetotalexpectedyieldforaHiggsbosonwidthandasquaredproduct ofthecouplingsscaledbyafactor10withrespecttotheirSMvalues.Inthetop plot,thebinsizevariesfrom20to85 GeV andthelastbinincludesallentrieswith massesabove800 GeV.

interference(P_intgg),asintroducedforthediscriminantcomputation inRef.[37].Thediscriminantisdeﬁnedas

Dgg= P gg tot Pgg tot+P qq bkg = 1+ P qq bkg a×P_siggg+√a×P_intgg+P_bkggg −1 , (4) where the parameter a is the strength of the unknown anoma-lousgg contributionwithrespecttotheexpectedSMcontribution (a=1).Weseta=10 inthedeﬁnitionof Dggaccordingtothe ex-pectedsensitivity.Studiesshowthattheexpectedsensitivitydoes not changesubstantially whena isvaried upordownbyafactor of2. Itshould bestressed thatﬁxing the parametera to agiven value onlyaffects the sensitivityof the analysis. Tosuppress the dominantqq→4backgroundintheon-shellregion,theanalysis also employs a MELA likelihood discriminant Dkin_bkg based on the JHUGenand mcfm matrix elementcalculationsforthesignaland

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Table 1

Expectedandobservednumbersofeventsinthe4and22νchannelsingg-enrichedregions,deﬁnedbym4≥ 330 GeV and Dgg>0.65 (4),andbymT>350 GeV andEmissT >100 GeV (22ν).Thenumbersofexpected eventsaregivenseparatelyfortheggandVBFprocesses,andforaSMHiggsboson(ΓH= ΓHSM)andaHiggs bosonwidthandsquaredproductofthecouplingsscaledbyafactor10withrespecttotheirSMvalues.The unphysicalexpectedcontributionsforthesignalandbackgroundcomponentsarealsoreportedseparately,forthe ggandVBFprocesses.Forbothprocesses,thesumofthesignalandbackgroundcomponentsdiffersfromthe totalduetothenegativeinterferences.Thequoteduncertaintiesincludeonlythesystematicsources.

4 22ν (a) Total gg (ΓH= ΓHSM) 1.8±0.3 9.6±1.5 gg Signal component (ΓH= ΓHSM) 1.3±0.2 4.7±0.6 gg Background component 2.3±0.4 10.8±1.7 (b) Total gg (ΓH=10× ΓHSM) 9.9±1.2 39.8±5.2 (c) Total VBF (ΓH= ΓHSM) 0.23±0.01 0.90±0.05 VBF signal component (ΓH= ΓHSM) 0.11±0.01 0.32±0.02 VBF background component 0.35±0.02 1.22±0.07 (d) Total VBF (ΓH=10× ΓHSM) 0.77±0.04 2.40±0.14 (e) qq background 9.3±0.7 47.6±4.0 (f) Other backgrounds 0.05±0.02 35.1±4.2 (a+c+e+f) Total expected (ΓH= ΓHSM) 11.4±0.8 93.2±6.0 (b+d+e+f) Total expected (ΓH=10× ΓHSM) 20.1±1.4 124.9±7.8 Observed 11 91

thebackground, asillustrated by the insetin Fig. 2 andused in Ref.[7].

Asanillustration,Fig. 3(top)presentsthe4invariantmass dis-tribution forthe off-shell signal region (m4>220 GeV) and for Dgg>0.65.Theexpectedcontributionsfromtheqq→4and re-duciblebackgrounds,aswellasforthetotalgluonfusion(gg)and vectorbosonfusion(VV)contributions,includingtheHiggsboson signal,are shown. Thedistribution of thelikelihood discriminant

Dgg form4>330 GeV isshowninFig. 3(bottom),together with

the expected contributions from the SM. The expected m4 and Dggdistributionsforthesumofalltheprocesses,withaHiggs bo-sonwidth ΓH=10× ΓHSM andarelativecrosssectionwithrespect to theSM cross section equal to unity inboth gluon fusion and VBFproductionmodes(μ=μggH=μVBF=1),arealsopresented, showingtheenhancementarisingfromthescalingofthesquared productofthecouplings.The expectedandobservedeventyields intheoff-shellgg-enrichedregiondeﬁnedbym4≥330 GeV and Dgg>0.65 arereportedinTable 1.

The22ν analysisisperformedonthe8 TeV datasetonly.The finalstateinthe22νchannelischaracterizedbytwo oppositely-charged leptons of the same flavor compatible with a Z boson, together witha large Emiss_T fromthe undetectable neutrinos. We requireEmiss_T >80 GeV.Theeventselection andbackground esti-mationisperformedasdescribed inRef.[16],withtheexception thatthejetcategoriesdefinedinRef.[16]areheregroupedintoa singlecategory, i.e.theanalysisisperformedinaninclusiveway. ThemT distributionintheoff-shellsignal region (mT>180 GeV) isshown in Fig. 4. The expected andobserved event yields in a gg-enrichedregiondefinedbymT>350 GeV and EmissT >100 GeV arereportedinTable 1.

Systematic uncertainties comprise experimental uncertainties onthe signal eﬃciencyand backgroundyield evaluation, aswell asuncertaintiesonthesignalandbackgroundfromtheoretical pre-dictions.SincethemeasurementisperformedinwidemZZregions, thereare sources ofsystematic uncertainties that only affectthe totalnormalizationandothers that affectboth thenormalization andtheshapeoftheobservablesusedinthisanalysis.Inthe4 ﬁ-nalstate,onlythelattertypeofsystematicuncertaintyaffectsthe measurementof ΓH,sincenormalizationuncertaintieschangethe on-shellandoff-shellyieldsbythesameamount.

Fig. 4. Distributionofthetransversemassinthe22νchannel.Pointsrepresentthe data,ﬁlledhistogramstheexpectedcontributionsfromthebackgrounds,andfrom thegluonfusion (gg)and vectorbosonfusion (VV)SMprocesses (includingthe Higgs-mediatedcontributions).Thedashedlinecorrespondstothetotalexpected yieldforaHiggsbosonwidthandasquaredproductofthecouplingsscaledbya factor10withrespecttotheirSMvalues.Thebinsizevariesfrom80to210 GeV andthelastbinincludesallentrieswithtransversemassesabove1 TeV.

Amongthesignaluncertainties,experimentalsystematic uncer-tainties are evaluated from observed events for the trigger effi-ciency (1.5%), and combined object reconstruction, identification andisolationefficiencies(3–4%formuons,5–11%forelectrons)[7]. Inthe22ν final state,theeffectsoftheleptonmomentumscale (1–2%)andjetenergyscale(1%)aretakenintoaccountand prop-agated to the evaluation of Emiss_T . The uncertainty in the b-jet veto(1–3%) isestimatedfromsimulationusing correctionfactors fortheb-taggingandb-misidentificationefficienciesasmeasured fromthedijetandtt decaycontrolsamples[38].

TheoreticaluncertaintiesfromQCDscalesintheqq background contribution are within 4–10% depending on mZZ [7]. An addi-tional uncertainty of 2–6% is included to account for missing higher order contributions with respect to a full NLO QCD and NLO EW evaluation. The systematic uncertainty in the

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normal-ization of the reducible backgrounds is evaluated following the methodsdescribed inRefs. [7,16].Inthe22ν channel,forwhich these contributions are not negligible at high mass, the estima-tionfromcontrolsamplesfortheZ+jets andforthesumofthe tt, tW and WW contributions leads to uncertainties of 25% and 15%inthe respectivebackgroundyields.Theoretical uncertainties inthe highmass contributionfrom thegluon-induced processes, whichaffectboththenormalizationandtheshape,areespecially importantinthisanalysis(inparticularforthesignaland interfer-encecontributionsthatarescaledbylargefactors).However,these uncertainties partiallycancelwhenmeasuring simultaneouslythe yieldfromthesameprocessintheon-shellsignalregion.The re-mainingmZZ-dependentuncertainties intheQCD renormalization andfactorization scales are derived usingthe K factor variations fromRef. [14],correspondingtoa factoroftwo upordownfrom thenominalmZZ/2 values,andamountto 2–4%.Forthegg→ZZ continuumbackgroundproduction,weassigna10%additional un-certainty on the K factor,following Ref. [22] andtaking into ac-countthedifferentmassrangesandselectionsonthespecificfinal state. This uncertainty also affects the interferencewith the sig-nal. The PDF uncertainties are estimated following Refs. [39,40] by changingthe NLO PDF set fromMSTW2008toCT10 [41] and NNPDF2.1[42],andtheresidualcontributionisabout1%.Forthe VBF processes, nosignificant mZZ-dependence is found regarding theQCDscales andPDF uncertainties,whichare ingeneralmuch smallerthanforthegluonfusionprocesses[8,9].Inthe22νfinal state,additional uncertaintieson theyield arisingfromthe theo-reticaldescription ofthepartonshower andunderlyingeventare takenintoaccount(6%).

Weperform a simultaneousunbinned maximumlikelihoodﬁt ofa signal-plus-background model to the measured distributions in the 4 and 22ν channels. In the 4 channel the analysis is performedin the on-shell and off-shell signal regions deﬁned above. In the on-shell region, a three-dimensional distribution

x= (m4, Dbkgkin, pT4orDjet) isanalyzed,followingthe methodol-ogydescribedinRef.[7],wherethequantity Djetisadiscriminant usedtoseparateVBFfromgluonfusionproduction.Intheoff-shell region,atwo-dimensional distributionx= (m4, Dgg)is analyzed. Inthe22ν channel,onlytheoff-shellHiggsbosonproductionis analyzed,usingthex=mT distribution.

The probability distribution functions are built using the full detector simulation or data control regions, and are deﬁned for the signal, the background, orthe interferencebetween the two contributions, Psig, Pbkg,or Pint,respectively,asafunctionofthe observablesx discussedabove.Severalproductionmechanismsare consideredforthesignalandthebackground,suchasgluonfusion (gg), VBF, and quark-antiquark annihilation (qq). The total prob-ability distribution function for the off-shell region includes the interferenceoftwocontributionsineachproductionprocess:

Poff-shell tot (x)= μggH× (ΓH/Γ0)×P_siggg(x) + μggH× (ΓH/Γ0)×P_intgg(x)+P_bkggg(x) +μVBF× (ΓH/Γ0)×PsigVBF(x) + μVBF× (ΓH/Γ0)×PintVBF(x)+PbkgVBF(x) +P_bkgqq(x)+ . . . (5)

Thelistofbackgroundprocessesisextendedbeyondthosequoted dependingonthe ﬁnalstate (Z+X,top,W+jets,WW,WZ).The parameters μggH and μVBF are the scale factors which modify the signal strength with respect to the reference parameteriza-tionineachproductionmechanismindependently.Theparameter

(ΓH/Γ0) is the scale factor which modiﬁes the observed width

Fig. 5. Scanofthenegativelog-likelihood,−2 lnL,asafunctionof ΓHfor the combinedﬁtofthe4and22ν channels(bluethicklines),forthe 4channel aloneintheoff-shellandon-shellregions(darkredlines),andforthe22νchannel intheoff-shellregionand4channelintheon-shellregion(lightredlines).The solidlinesrepresenttheobservedvalues,thedottedlinestheexpectedvalues.(For interpretationofthereferencestocolorinthisﬁgurelegend,thereaderisreferred tothewebversionofthisarticle.)

withrespect tothe Γ0 value used inthereference parameteriza-tion.

Intheon-shellregion,theparameterizationincludesthesmall contribution of the ttH and VH Higgs boson production mecha-nisms, whichare relatedto the gluon fusion and VBF processes, respectively, because either the quark or the vector boson cou-pling to the Higgs boson is in common among those processes. Interferenceeffectsare negligibleintheon-shellregion.Thetotal probability distributionfunctionfortheon-shellregion iswritten as Pon-shell tot (x)=μggH× Pgg sig(x)+P ttH sig(x) +μVBF PVBF sig (x)+PsigVH(x) +Pqq bkg(x)+P gg bkg(x)+ . . . (6)

The above parameterizations inEqs. (5, 6) are performedforthe tree-level HVV coupling ofa scalarHiggs boson, consistent with our observations [4,7]. We ﬁnd that the presence of anomalous couplingsintheHVVinteractionwouldleadtoenhancedoff-shell productionandamorestringentconstraintonthewidth. Itis ev-ident thatthe parameterizationin Eq.(5)relies onthe modeling ofthegluonfusionproductionwiththedominanttop-quarkloop, thereforenopossiblenewparticlesareconsideredintheloop. Fur-therdiscussioncanalsobefoundinRefs.[43–45].

Thethreeparameters ΓH, μggH,and μVBFareleftunconstrained intheﬁt.The μggH and μVBF ﬁttedvaluesarefoundtobe almost identicaltothoseobtainedinRef.[7].Systematicuncertaintiesare includedasnuisanceparametersandaretreatedaccordingto the frequentist paradigm [46]. The shapesand normalizations of the signal and of each background component are allowed to vary within their uncertainties, and thecorrelations in the sources of systematicuncertaintyaretakenintoaccount.

The ﬁt results are shown in Fig. 5 as scans of the negative log-likelihood,−2 lnL,asa functionof ΓH. Combiningthe two channels a limit is observed (expected) on the total width of

ΓH<22 MeV (33 MeV)ata95% CL,whichis5.4(8.0) timesthe expected value in the SM. The best ﬁt value and 68% CL inter-valcorrespondto ΓH=1.8+₋71..78 MeV.The resultofthe4analysis

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aloneis an observed (expected)limit of ΓH<33 MeV (42 MeV) ata 95% CL,which is8.0(10.1) times theSM value, andthe re-sultoftheanalysiscombiningthe 4 on-shelland22ν off-shell regionsis ΓH<33 MeV (44 MeV)ata95%CL,whichis8.1(10.6) timesthe SM value. The bestﬁt valuesand 68% CLintervals are

ΓH=1.9+₋111.9.7MeV and ΓH=1.8₋+112.8.4 MeV forthe4analysisand fortheanalysiscombiningthe 4 on-shell and22ν off-shell re-gions,respectively.

Theexpectedlimitforthetwochannelscombinedwithout in-cludingthesystematicuncertainties is ΓH<28 MeV ata 95%CL. Theeffectofsystematicuncertainties isdrivenbythe22ν chan-nelwithlargerexperimentaluncertaintiesinsignaleﬃcienciesand background estimation from control samples in data, while the resultinthe4channelislargelydominatedbythestatistical un-certainty.

The statistical compatibility of the observed results with the expectation under the SM hypothesis corresponds to a p-value of 0.24. The statistical coverage of the results obtained in the likelihood scan has also been tested with the Feldman–Cousins approach[47] forthecombinedanalysis leadingto consistent al-thoughslightlytighterconstraints.Theanalysisinthe4 channel hasalsobeenperformedinaone-dimensionalﬁtusingeitherm4

orDgg andconsistentresultsarefound.Theexpectedlimit with-out using theMELA likelihood discriminant Dgg is 40% larger in the4channel.

Insummary,wehavepresentedconstraintson thetotalHiggs bosonwidthusingitsrelativeon-shellandoff-shellproductionand decayratestofourleptonsortwoleptonsandtwoneutrinos.The analysisisbasedonthe2011and2012datasetscorrespondingto integratedluminosities of5.1 fb−1 at √s=7 TeV and 19.7 fb−1 at √s=8 TeV. The four-lepton analysis uses the measured in-variant mass distribution near the peak and above the Z-boson pairproductionthreshold,aswell asa likelihooddiscriminant to separate thegluon fusionZZproduction fromtheqq→ZZ back-ground,while thetwo-lepton plustwo-neutrinooff-shellanalysis reliesonthe transversemassdistribution. Thepresentedanalysis determinestheindependentcontributionsofthegluonfusionand VBFproductionmechanismsfromthedataintheon-shellregion. Itreliesneverthelessonthe knowledgeofthecouplingratios be-tweentheoff-shellandon-shellproduction,i.e.thedominanceof thetopquarkloopinthegluonfusionproductionmechanismand theabsenceofnewparticlecontributionintheloop.Thepresence ofanomalous couplingsintheHVVinteractionwouldleadto en-hancedoff-shellproductionandwouldmakeourconstrainttighter. Thecombinedﬁt ofthe4 and22ν channelsleads to anupper limit onthe Higgsboson widthof ΓH<22 MeV at a 95% conﬁ-dencelevel,whichis5.4timestheexpectedwidthoftheSMHiggs boson.Thisresultimprovesbymorethantwoordersofmagnitude upon previous experimental constraints onthe new bosondecay widthfromthedirectmeasurementattheresonancepeak.

Acknowledgements

We wish to thankour theoretician colleagues andin particu-larFabrizioCaolafor providingthe theoreticaluncertainty inthe gg→ZZ background K factor, Tobias Kasprzik for providing the numerical calculations on the EW corrections for the qq→ZZ backgroundprocess,GiampieroPassarinoforhiscalculationsofthe mZZ-dependent K factor and its variations with renormalization and factorization scales, and Marco Zaro for checking the inde-pendenceonmZZ ofhigher-ordercorrectionsinVBFprocesses.We alsogratefullyacknowledgeAlessandroBallestrero,JohnCampbell, KeithEllis,StefanoForte,NikolasKauer,KirillMelnikov,andCiaran Williamsfor their helpin optimizingthe MonteCarlogenerators forthisanalysis.

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrative staffsatCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcenters and personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythe computinginfrastructureessential to ouranalyses. Finally, we acknowledge the enduring support for the construc-tionandoperation oftheLHC andtheCMSdetectorprovidedby the following funding agencies: BMWF and FWF(Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIEN-CIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, SF0690030s09andERDF(Estonia);AcademyofFinland,MEC,and HIP(Finland);CEAandCNRS/IN2P3(France);BMBF,DFG,andHGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India);IPM(Iran); SFI(Ireland);INFN (Italy); NRF andWCU (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portu-gal);JINR(Dubna);MON,RosAtom,RASandRFBR(Russia);MESTD (Serbia);SEIDIandCPAN(Spain);SwissFundingAgencies (Switzer-land); NSC (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thai-land);TUBITAKandTAEK(Turkey);NASUandSFFR(Ukraine);STFC (UnitedKingdom);DOEandNSF(USA).

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CMSCollaboration

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

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, T. Bergauer, M. Dragicevic,J. Erö, C. Fabjan1,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,A. Taurok,

W. Treberer-Treberspurg,W. Waltenberger, C.-E. Wulz1

InstitutfürHochenergiephysikderOeAW,Wien,Austria

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

NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

S. Alderweireldt, M. Bansal, S. Bansal, T. Cornelis,E.A. De Wolf,X. Janssen, A. Knutsson,S. Luyckx,

S. Ochesanu,B. Roland, R. Rougny, M. Van De Klundert, H. Van Haevermaet,P. Van Mechelen,

N. Van Remortel,A. Van Spilbeeck

(8)

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

VrijeUniversiteitBrussel,Brussel,Belgium

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

A. Mohammadi, L. Perniè2,T. Reis, T. Seva, L. Thomas, C. Vander Velde, P. Vanlaer,J. Wang

UniversitéLibredeBruxelles,Bruxelles,Belgium

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

J. Mccartin,A.A. Ocampo Rios, 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, 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, M.E. Pol

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, T.R. Fernandez Perez Tomeia,E.M. Gregoresb,P.G. Mercadanteb,S.F. Novaesa,

Sandra S. Padulaa

a

UniversidadeEstadualPaulista,SãoPaulo,Brazil

b_Universidade_Federal_do_ABC,_São_Paulo,_Brazil

A. Aleksandrov, V. Genchev2, P. Iaydjiev, A. Marinov,S. Piperov, M. Rodozov,G. Sultanov, M. Vutova

InstituteforNuclearResearchandNuclearEnergy,Soﬁa,Bulgaria

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

UniversityofSoﬁa,Soﬁa,Bulgaria

J.G. Bian,G.M. Chen, H.S. Chen, M. Chen, R. Du,C.H. Jiang, D. Liang,S. Liang,R. Plestina7, J. Tao,

X. Wang,Z. Wang

InstituteofHighEnergyPhysics,Beijing,China

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

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

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

UniversidaddeLosAndes,Bogota,Colombia

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

(9)

Z. Antunovic, M. Kovac

UniversityofSplit,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

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, G. Fedi,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

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, C. Charlot, T. Dahms, M. Dalchenko,L. Dobrzynski, N. Filipovic,

A. Florent,R. Granier de Cassagnac, M. Machet, L. Mastrolorenzo, P. Miné, C. Mironov, I.N. Naranjo,

M. Nguyen, C. Ochando, P. Paganini,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, P. Van Hove

InstitutPluridisciplinaireHubertCurien,UniversitédeStrasbourg,UniversitédeHauteAlsaceMulhouse,CNRS/IN2P3,Strasbourg,France

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,N. Beaupere, G. Boudoul2,E. Bouvier, S. Brochet, C.A. Carrillo Montoya, J. Chasserat,

R. Chierici,D. Contardo2,P. Depasse,H. El Mamouni, J. Fan, J. Fay, S. Gascon, M. Gouzevitch, B. Ille,

T. Kurca, M. Lethuillier, L. Mirabito,S. Perries, J.D. Ruiz Alvarez,D. Sabes, L. Sgandurra,V. Sordini,

M. Vander Donckt, P. Verdier, S. Viret,H. Xiao

(10)

Z. Tsamalaidze8

InstituteofHighEnergyPhysicsandInformatization,TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann,S. Beranek, M. Bontenackels, M. Edelhoff,L. Feld, O. Hindrichs, K. Klein, A. Ostapchuk,

A. Perieanu,F. Raupach, J. Sammet,S. Schael, H. Weber, B. Wittmer, V. Zhukov5

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

M. Ata, 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, M. Weber

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, J. Lingemann2,A. Nowack, I.M. Nugent,L. Perchalla, O. Pooth, A. Stahl

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

I. Asin,N. Bartosik, J. Behr,W. Behrenhoff, U. Behrens,A.J. Bell, M. Bergholz15,A. Bethani, K. Borras,

A. Burgmeier,A. Cakir,L. Calligaris, A. Campbell, S. Choudhury, F. Costanza, C. Diez Pardos,S. Dooling,

T. Dorland,G. Eckerlin, D. Eckstein, T. Eichhorn, G. Flucke, J. Garay Garcia, A. Geiser, P. Gunnellini,

J. Hauk, G. Hellwig,M. Hempel, D. Horton, H. Jung, A. Kalogeropoulos,M. Kasemann, P. Katsas,

J. Kieseler, C. Kleinwort,D. Krücker, W. Lange, J. Leonard,K. Lipka, A. Lobanov,W. Lohmann15,B. Lutz,

R. Mankel, I. Marﬁn,I.-A. Melzer-Pellmann, A.B. Meyer, J. Mnich, A. Mussgiller, S. Naumann-Emme,

A. Nayak,O. Novgorodova, F. Nowak,E. Ntomari, H. Perrey,D. Pitzl, R. Placakyte, A. Raspereza,

P.M. Ribeiro Cipriano,E. Ron, M.Ö. Sahin,J. Salfeld-Nebgen, P. Saxena, R. Schmidt15,

T. Schoerner-Sadenius,M. Schröder, C. Seitz,S. Spannagel, A.D.R. Vargas Trevino, R. Walsh, C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

M. Aldaya Martin,V. Blobel, M. Centis Vignali, A.r. Draeger,J. Erﬂe, E. Garutti, K. Goebel, M. Görner,

J. Haller, M. Hoffmann,R.S. Höing, H. Kirschenmann,R. Klanner, R. Kogler, J. Lange,T. Lapsien, T. Lenz,

I. Marchesini,J. Ott, T. Peiffer, N. Pietsch, T. Pöhlsen, D. Rathjens, C. Sander,H. Schettler, P. Schleper,

E. Schlieckau,A. Schmidt, M. Seidel, J. Sibille16,V. Sola, H. Stadie,G. Steinbrück, D. Troendle, E. Usai,

L. Vanelderen

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, F. Hartmann2, T. Hauth2,U. Husemann, I. Katkov5,A. Kornmayer2,

E. Kuznetsova, P. Lobelle Pardo, M.U. Mozer,Th. Müller, A. Nürnberg, G. Quast, K. Rabbertz, F. Ratnikov,

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. Panagiotou,N. Saoulidou, E. Stiliaris

UniversityofAthens,Athens,Greece

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

UniversityofIoánnina,Ioánnina,Greece

G. Bencze,C. Hajdu, P. Hidas,D. Horvath17, F. Sikler,V. Veszpremi, G. Vesztergombi18, A.J. Zsigmond

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N. Beni, S. Czellar, J. Karancsi19,J. Molnar, J. Palinkas, Z. Szillasi

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

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

UniversityofDebrecen,Debrecen,Hungary

S.K. Swain

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

S.B. Beri, V. Bhatnagar,N. Dhingra, R. Gupta, U. Bhawandeep, A.K. Kalsi, M. Kaur, 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, S. Kailas,V. Kumar, A.K. Mohanty2, L.M. Pant, P. Shukla,A. Topkar

BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz, S. Bhowmik20,R.M. Chatterjee, S. Ganguly,S. Ghosh, M. Guchait21, A. Gurtu22, G. Kole,

S. Kumar, M. Maity20,G. Majumder, K. Mazumdar, G.B. Mohanty, B. Parida,K. Sudhakar,

N. Wickramage23

TataInstituteofFundamentalResearch- EHEP,Mumbai,India

S. Banerjee, R.K. Dewanjee, S. Dugad

TataInstituteofFundamentalResearch- HECR,Mumbai,India

H. Bakhshiansohi,H. Behnamian, S.M. Etesami24, A. Fahim25, R. Goldouzian, A. Jafari,M. Khakzad,

M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi, B. Safarzadeh26, M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

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

N. De Filippisa,c, M. De Palmaa,b,L. Fiorea,G. Iasellia,c,G. Maggia,c,M. Maggia, S. Mya,c, S. Nuzzoa,b, A. Pompilia,b,G. Pugliesea,c,R. Radognaa,b,2, G. Selvaggia,b, L. Silvestrisa,2,G. Singha,b, R. Vendittia,b,

P. Verwilligena, G. Zitoa

a_INFN_Sezione_di_Bari,_Bari,_Italy b

UniversitàdiBari,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, G. Codispotia,b, M. Cuﬃania,b,

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S. Marcellinia, G. Masettia,2, A. Montanaria, F.L. Navarriaa,b,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, G. Cappelloa,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 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. Goria,b,2,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

INFNLaboratoriNazionalidiFrascati,Frascati,Italy

F. Ferroa, M. Lo Veterea,b, E. Robuttia,S. Tosia,b

a_INFN_Sezione_di_Genova,_Genova,_Italy b_Università_di_Genova,_Genova,_Italy

M.E. Dinardoa,b, S. Fiorendia,b,2, S. Gennaia,2,R. Gerosa2, A. Ghezzia,b,P. Govonia,b,M.T. Lucchinia,b,2,

S. Malvezzia, R.A. Manzonia,b, A. Martellia,b, B. Marzocchi,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,S. Di Guidaa,d,2, 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, D. Biselloa,b, A. Brancaa,b,R. Carlina,b,P. Checchiaa, M. Dall’Ossoa,b, T. Dorigoa,U. Dossellia, M. Galantia,b,F. Gasparinia,b,U. Gasparinia,b,P. Giubilatoa,b,

A. Gozzelinoa, K. Kanishcheva,c,S. Lacapraraa, M. Margonia,b, A.T. Meneguzzoa,b,

J. Pazzinia,b, N. Pozzobona,b, P. Ronchesea,b,F. Simonettoa,b, E. Torassaa,M. Tosia,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. Salvinia,P. Vituloa,b

a_INFN_Sezione_di_Pavia,_Pavia,_Italy b_Università_di_Pavia,_Pavia,_Italy

M. Biasinia,b,G.M. Bileia,D. Ciangottinia,b, L. Fanòa,b,P. Laricciaa,b,G. Mantovania,b, M. Menichellia, F. Romeoa,b_,_{A. Saha}a_,_{A. Santocchia}a,b_, _{A. Spiezia}a,b,2

a_INFN_Sezione_di_Perugia,_Perugia,_Italy b_Università_di_Perugia,_Perugia,_Italy

K. Androsova,27,P. Azzurria,G. Bagliesia,J. Bernardinia,T. Boccalia,G. Broccoloa,c,R. Castaldia,

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T. Lomtadzea, L. Martinia,b, A. Messineoa,b,C.S. Moona,28, F. Pallaa,2, A. Rizzia,b, A. Savoy-Navarroa,29, A.T. Serbana,P. Spagnoloa,P. Squillaciotia,27,R. Tenchinia, G. Tonellia,b,A. Venturia,

P.G. Verdinia, C. Vernieria,c,2

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, G. D’imperioa,b,D. Del Rea,b,M. Diemoza, M. Grassia,b, C. Jordaa,E. Longoa,b,F. Margarolia,b,P. Meridiania, F. Michelia,b,2, S. Nourbakhsha,b, G. Organtinia,b,R. Paramattia, S. Rahatloua,b,C. Rovellia, F. Santanastasioa,b,

L. Soﬃa,b,2, P. Traczyka,b

a_INFN_Sezione_di_Roma,_Roma,_Italy b_Università_di_Roma,_Roma,_Italy

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

E. Migliorea,b,V. Monacoa,b,M. Musicha,M.M. Obertinoa,c,2, G. Ortonaa,b,L. Pachera,b,N. Pastronea, M. Pelliccionia,G.L. Pinna Angionia,b, A. Potenzaa,b,A. Romeroa,b, M. Ruspaa,c,R. Sacchia,b,

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

a_INFN_Sezione_di_Torino,_Torino,_Italy b_Università_di_Torino,_Torino,_Italy

c_Università_del_Piemonte_Orientale_(Novara),_Torino,_Italy

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

a_INFN_Sezione_di_Trieste,_Trieste,_Italy b_Università_di_Trieste,_Trieste,_Italy

T.J. Kim

ChonbukNationalUniversity,Chonju,Korea

S. Chang, A. Kropivnitskaya,S.K. Nam

KangwonNationalUniversity,Chunchon,Korea

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,Korea

J.Y. Kim, S. Song

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,Korea

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

KoreaUniversity,Seoul,Korea

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

UniversityofSeoul,Seoul,Korea

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

SungkyunkwanUniversity,Suwon,Korea

A. Juodagalvis

VilniusUniversity,Vilnius,Lithuania

J.R. Komaragiri, M.A.B. Md Ali

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H. Castilla-Valdez,E. De La Cruz-Burelo, I. Heredia-de La Cruz30,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

E. Casimiro Linares, 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, S. Khalid, W.A. Khan, T. Khurshid,M.A. Shah, M. Shoaib

NationalCentreforPhysics,Quaid-I-AzamUniversity,Islamabad,Pakistan

H. Bialkowska,M. Bluj31,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, W. Wolszczak

InstituteofExperimentalPhysics,FacultyofPhysics,UniversityofWarsaw,Warsaw,Poland

P. Bargassa,C. Beirão Da Cruz E Silva, P. Faccioli, P.G. Ferreira Parracho,M. Gallinaro, F. Nguyen,

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

LaboratóriodeInstrumentaçãoeFísicaExperimentaldePartículas,Lisboa,Portugal

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

A. Lanev,A. Malakhov,V. Matveev32, P. Moisenz, V. Palichik,V. Perelygin, S. Shmatov, N. Skatchkov,

V. Smirnov,A. Zarubin

JointInstituteforNuclearResearch,Dubna,Russia

V. Golovtsov,Y. Ivanov, V. Kim33,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, G. Safronov, S. Semenov, A. Spiridonov, V. Stolin,

E. Vlasov,A. Zhokin

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

P.N.LebedevPhysicalInstitute,Moscow,Russia

A. Belyaev,E. Boos, V. Bunichev, M. Dubinin34, L. Dudko,A. Ershov, A. Gribushin,V. Klyukhin,

O. Kodolova,I. Lokhtin, S. Obraztsov,S. Petrushanko,V. Savrin

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. Adzic35, 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,G. Merino, 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, L. Lloret Iglesias

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

InstitutodeFísicadeCantabria(IFCA),CSIC–UniversidaddeCantabria,Santander,Spain

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

L. Benhabib,J.F. Benitez, C. Bernet7,G. Bianchi, P. Bloch, A. Bocci, A. Bonato, O. Bondu,C. Botta,

H. Breuker, T. Camporesi, G. Cerminara, S. Colafranceschi36,M. D’Alfonso, D. d’Enterria, A. Dabrowski,

A. David,F. De Guio, A. De Roeck, S. De Visscher, M. Dobson, M. Dordevic, N. Dupont-Sagorin,

A. Elliott-Peisert, J. Eugster,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, P. Musella, L. Orsini,

L. Pape,E. Perez, L. Perrozzi,A. Petrilli, G. Petrucciani, A. Pfeiffer,M. Pierini, M. Pimiä, D. Piparo,

M. Plagge, A. Racz,G. Rolandi37, M. Rovere,H. Sakulin, C. Schäfer, C. Schwick,A. Sharma, P. Siegrist,

P. Silva,M. Simon, P. Sphicas38,D. Spiga, J. Steggemann,B. Stieger, M. Stoye, D. Treille, A. Tsirou,

G.I. Veres18, J.R. Vlimant, 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

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

G. Dissertori, M. Dittmar, M. Donegà, M. Dünser, P. Eller, C. Grab,D. Hits, W. Lustermann,B. Mangano,

A.C. Marini,P. Martinez Ruiz del Arbol, D. Meister, N. Mohr,C. Nägeli39,F. Nessi-Tedaldi, F. Pandolﬁ,

F. Pauss,M. Peruzzi, M. Quittnat,L. Rebane, M. Rossini, A. Starodumov40,M. Takahashi, K. Theoﬁlatos,

R. Wallny,H.A. Weber

InstituteforParticlePhysics,ETHZurich,Zurich,Switzerland

C. Amsler41,M.F. Canelli, V. Chiochia,A. De Cosa, A. Hinzmann, T. Hreus, B. Kilminster, C. Lange,

B. Millan Mejias, J. Ngadiuba,P. Robmann, F.J. Ronga,S. Taroni, M. Verzetti, 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.W. Chang,Y. Chao, K.F. Chen, P.H. Chen, C. Dietz,U. Grundler,W.-S. Hou,K.Y. Kao,

Y.J. Lei, Y.F. Liu,R.-S. Lu, D. Majumder, E. Petrakou, Y.M. Tzeng,R. Wilken

NationalTaiwanUniversity(NTU),Taipei,Taiwan

B. Asavapibhop,N. Srimanobhas, N. Suwonjandee

ChulalongkornUniversity,Bangkok,Thailand

A. Adiguzel, M.N. Bakirci42,S. Cerci43, C. Dozen,I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut,

E. Gurpinar,I. Hos, E.E. Kangal, A. Kayis Topaksu,G. Onengut44, K. Ozdemir, S. Ozturk42, A. Polatoz,

K. Sogut45, D. Sunar Cerci43,B. Tali43, H. Topakli42,M. Vergili

CukurovaUniversity,Adana,Turkey

I.V. Akin,B. Bilin, S. Bilmis, H. Gamsizkan, G. Karapinar46,K. Ocalan, S. Sekmen, U.E. Surat,M. Yalvac,

M. Zeyrek

MiddleEastTechnicalUniversity,PhysicsDepartment,Ankara,Turkey

E. Gülmez,B. Isildak47,M. Kaya48,O. Kaya49

BogaziciUniversity,Istanbul,Turkey

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

IstanbulTechnicalUniversity,Istanbul,Turkey

L. Levchuk,P. Sorokin

NationalScientiﬁcCenter,KharkovInstituteofPhysicsandTechnology,Kharkov,Ukraine

J.J. Brooke,E. Clement, D. Cussans,H. Flacher, R. Frazier,J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath,

J. Jacob,L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold51,S. Paramesvaran,A. Poll, S. Senkin, V.J. Smith,

T. Williams

UniversityofBristol,Bristol,UnitedKingdom

K.W. Bell,A. Belyaev52,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, W.J. Womersley, S.D. Worm

RutherfordAppletonLaboratory,Didcot,UnitedKingdom

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

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