Combined search for anomalous pseudoscalar HVV couplings in VH(H -> b(b)over-bar) production and H -> VV decay

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Physics

Letters

B

www.elsevier.com/locate/physletb

Combined

search

for

anomalous

pseudoscalar

HVV couplings

in VH(H

→

bb)

production

and

H

→

VV decay

.TheCMS Collaboration CERN,Switzerland

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

Articlehistory:

Received13February2016

Receivedinrevisedform15May2016 Accepted2June2016

Availableonline7June2016 Editor:M.Doser Keywords: CMS Physics Higgs BSM

A search for anomalous pseudoscalarcouplings of the Higgs bosonH to electroweak vector bosons V (=W orZ)inasampleofproton–protoncollisioneventscorresponding toanintegratedluminosity of18.9 fb−1_{atacenter-of-massenergyof8 TeV ispresented.Eventsconsistentwiththe topologyof}

associatedVH production,wheretheHiggsbosondecaystoapairofbottomquarksandthevectorboson decays leptonically,are analyzed.The consistencyof data with a potential pseudoscalar contribution to theHVV interaction,expressedbytheeffectivepseudoscalarcrosssectionfractions fa3,isassessed by meansofprofilelikelihoodscans. Resultsare givenfor theVH channelsaloneand foracombined analysisoftheVH andpreviouslypublishedH→VV channels.Undercertainassumptions, fZZ

a3 >0.0034 isexcludedat95%confidencelevelinthecombination.Scenariosinwhichtheseassumptionsarerelaxed arealsoconsidered.

©2016TheAuthor.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3.

1. Introduction

The observation of a new boson [1–3] with a mass around 125 GeV and properties consistent with those of the standard model(SM)Higgsboson[4–10]hasusheredinaneweraof preci-sionHiggsphysics.TheATLASandCMSCollaborations attheCERN LHC havebegun a comprehensive studyof the boson properties. The spin-parity ofthe Higgs bosonhas been studiedin H→ZZ, Zγ∗, γ∗γ∗→4,H→WW→ νν,andH→γ γ decays[11–16], where  isan electron ormuon. The CDFand D0 Collaborations have set limits on the pp→VH production cross section (with V=W or Z)attheTevatron,fortwo exoticspin-parity modelsof theHiggsboson[17].Inallcases,thespin-parity JC P _oftheboson hasbeenfoundtobeconsistentwiththeSMprediction.Basedon astudyofanomalous couplingsinH→ZZ→4decays,theCMS Collaboration hasexcluded thehypothesis ofa pure pseudoscalar spin-zero boson at 99.98% confidence level (CL), while an effec-tive pseudoscalarcrosssection fraction f_aZZ₃ >0.43 is excluded at 95%CL(assuminga positive,realvaluedratioofscalarand pseu-doscalarcouplings) [15].Under thesameassumptions, theATLAS Collaboration hasexcluded fZZ

a3 >0.11 at95%CL[18].

We present here the first search for anomalous pseudoscalar HVV couplings atthe LHC in the topology of associated produc-tion,VH.ItwillbeshownthattheVHchannelsarestrongprobes

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

of the structure of the HVV interaction, with sensitivity even to smallanomalous couplings.The ultimateLHC sensitivitytoa po-tential pseudoscalar interaction in these channelsis expected to greatly exceed that of H→VV [19]. Due to the highly off-shell natureofthepropagatorinVHproduction,smallanomalous cou-plings can lead to significant modifications of cross sectionsand kinematic features. In particular, the propagator mass, measured bytheVHinvariantmass,m(VH),ishighlysensitivetoanomalous HVV couplings[20].

Results from the VH channels are ultimately combined with thosefromH→VV measurements[15].Theqq→VH→Vbb and gg→H→VV processesinvolvetheYukawafermioncouplingHff andthesameHVV coupling,assuminggluon fusionproductionis dominated by the top-quark loop. The dominance of the gluon fusion production mechanism of the Higgs boson at the LHC is supported byexperimental measurements [4–10].Itisinteresting to consider modelswhere theratio ofthe Hbb and Htt coupling strengths intheVHandH→VV processesis notaffectedby the presenceofanomalouscontributions[21].Insuchacase,itis pos-sibletorelatethecrosssectionsofthetwoprocessesforarbitrary anomalousHVV couplingsandperformacombinedanalysisofthe VHandH→VV processes,exploitingbothkinematicsandthe rel-ative signal strengths of the two processes. The H→VV signal strengthisrelativelywellmeasuredandcanprovideastrong con-straintontheVHsignalstrength.Formodestvaluesof fZZ

a3,theVH

signalstrengthisconstrainedtolargevalues.Theaddedconstraint

http://dx.doi.org/10.1016/j.physletb.2016.06.004

0370-2693/©2016TheAuthor.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

thereby significantly improves the sensitivity to anomalous cou-plings.

Inthe following, we consider only the interactions of a spin-zero boson with the W and Z bosons, for which the scattering amplitudeisparameterizedas A(HVV)∼  aHVV₁ +κ HVV 1 q2V1+κ HVV 2 q2V2  HVV₁ 2  m2_V 1 ∗ V1 ∗ V2 +aHVV₂ f_μν∗(1)f∗(2)μν+aHVV₃ f_μν∗(1)˜f∗(2)μν, (1)

wheretheaHVV_i arearbitrarycomplexcouplingparameterswhich candependontheV1 andV2 squaredfour-momenta,q2_V

1 andq

2 V2;

f(i)_{μν isthefield strengthtensorofagaugebosonwith}

momen-tumqVi andpolarizationvector Vi,givenby 

μ ViqνVi− ν Viq μ Vi; ˜f (i) μν is thedualfield strength tensor,givenby 1₂μνρσ f(i)ρσ ;mV1 isthe

pole mass of the vector boson; and HVV₁ is the energy scale wherephenomena not includedin theSM become relevant [19]. The aHVV

1 , κiHVV and aHVV2 terms represent parity-conserving in-teractions of a scalar, while the aHVV

3 term represents a parity-conserving interaction of a pseudoscalar. In the SM, aHVV₁ =2, whichis theonly nonzerocoupling attreelevel. Allother terms inEq.(1)aregeneratedwithintheSMby loop-inducedprocesses atlevelsbelowcurrentexperimentalsensitivity.Therefore,any ev-idenceforthesetermsintheavailable datashouldbeinterpreted asevidenceofnewphysics.

WesearchforananomalousaHVV₃ termoftheHVV interaction, assumingthatthe κHVV

i andaHVV2 termsarenegligible.Throughout theremainder of the paper,the term“scalar interaction” will be used todescribe theaHVV

1 term. The effective pseudoscalarcross sectionfractionforprocess j (WH,ZH,WW,orZZ)isdefinedas

faj3=

aHVV₃ 2σ₃j

aHVV₁ 2σ₁j+aHVV₃ 2σ₃j, (2)

where σ_ij is the production cross-section for process j with aHVV

i =1 and all other couplings assumed to be equal to zero. A superscript is not included when making a general statement notrelatedtoaparticularprocess.Thepurelyscalar(pseudoscalar) casecorrespondsto fa3=0 ( fa3=1).Thesignalstrength

parame-ter μj _{forprocess j canalsobedefinedintermsofthea}HVV i as μj=a HVV 1  2 σ₁j+aHVV 3  2 σ₃j  aHVV_1,SM_2σ₁j . (3)

Foragivensetofcouplingconstants, thephysicalobservables faj3

and μj _{varyfordifferentprocessesasaresultofthedependence} onthe σ_ij.The fZH

a3 and f

WH

a3 variables are defined withrespect

to the ZH and WH production cross-sections in √s=8 TeV pp collisions, whereas the fVV

a3 variables are definedwithrespect to

the cross-section times branching fraction for the corresponding pp→H→VV process. Inthe lattercase, thedependence onthe pp→H cross-sectioncancels.

2. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ingsolenoidof 6 m internaldiameter,providing amagnetic field of3.8 T.Withinthesolenoidvolume area siliconpixelandstrip tracker,aleadtungstatecrystalelectromagneticcalorimeter,anda

brassandscintillatorhadroncalorimeter,eachcomposedofa bar-relandtwo endcapsections.Extensive forwardcalorimetry com-plements the coverage provided by thebarrel andendcap detec-tors.Muonsaremeasuredingas-ionizationdetectorsembeddedin the steel flux-return yoke outside the solenoid. A more detailed descriptionofthe CMSdetector,togetherwitha definitionofthe coordinatesystemused andtherelevant kinematicvariables,can befoundinRef.[22].

3. Analysisstrategy

The analysisisbased ona datasample ofpp collisions corre-spondingto an integratedluminosity of18.9 fb−1 _ata center-of-massenergyof8 TeV,collectedwithsingle-electron,single-muon, and double-electrontriggers. The final states considered are νjj andjj (wherej representsa jet),targetingtheWH andZH sig-nalsrespectively.

The trigger, object and event selection criteria, and back-ground modeling are identical to those of Ref. [23]. Using the selected events,the two-dimensional template method described inRef.[15]isusedtodetermine fa3 confidenceintervals.The

dis-criminantoftheboosteddecisiontree(BDT)describedinRef.[23] servesasonedimensionofthetemplates.ThisBDTistrained sep-aratelyforthe WH andZHchannelstoexploit various kinematic features typical of signal and background, and the correlations amongobservables. Theb-tagging likelihooddiscriminants of the jets used to construct the Higgs boson candidate, the invariant massoftheHiggsbosoncandidate,andtheangularseparation be-tweenfinalstateleptonsandjetsarethemostimportantvariables intermsofbackgroundrejection.Althoughinitiallytrainedto sep-arate background from a scalar Higgs boson signal, it has been demonstratedwithsimulatedeventsthattheBDTisalsoeffective for signalswith anomalous fa3 values. The second dimension of

the templates ism(VH).Effectively, the BDT dimension provides abackground-depletedregion athighvaluesoftheBDT discrimi-nantwithwhichtotestvarioussignalhypothesesusingthem(VH)

distribution.

Signaltemplatesinthex= {BDT,m(VH)}planeareconstructed forarbitraryvaluesof fa3 fromalinearsuperpositionoftemplates

representingthe pure scalar(P0+   x) andpseudoscalar(P0−   x) hypotheses anda template (P₀int+_,0−

  x; φa3



) that accountsfor in-terferencebetweentheaHVV₁ andaHVV₃ termsinEq.(1),asfollows:

Psig   x;fa3, φa3  =1−fa3  P0+   x+ fa3P0−   x +fa3  1− fa3  Pint 0+,0−  x; φa3  . (4)

The phase between the aHVV₁ and aHVV₃ couplings is represented by φa3. The interference contributions to the BDT discriminant

andm(VH)distributionsare negligible,asverifiedwithsimulated events. Therefore the last term in Eq. (4) is ignored in the VH channels. Equation (4) is also used to parameterize the H→VV signals. Anomalous couplings that result from loops with parti-clesmuchheavierthan theHiggsbosonarerealvalued, allowing phasesof0and π.IntheH→VV channels,we assume φa3=0.

The resulting templates are used to perform profile likelihood scans [24] to assessthe consistency ofvarious signal hypotheses withthedata.One-dimensionalprofilelikelihoodscansof fa3 are

performed(where μisprofiled),aswellastwo-dimensionalscans inthe μversus fa3 plane.

In order to combine channels that depend on the aHZZ_i with thosedepending ontheaHWW_i , someassumptionon the relation-shipbetweenthecouplingsisrequired,andcustodialsymmetryis assumed(aHZZ

Table 1

σ1/σ3 cross sectionratioscalculated

with JHUGen. Process σ1/σ3 WH 0.0174 ZH 0.0239 WW 3.01 ZZ 6.36 Table 2 Valuesof i,j

whichrelatethe chan-nelsstudiedinthispaper,asdefined inEq.(7). i, j i,j ZH, WH 1.37 ZZ, WW 2.11 ZZ, ZH 266 WW, WH 173

Withtheseassumptions,the fa3 and μvaluesintheWH andZH

channelsarerelatedby

f_aWH 3 =  1+ 1 ZH,WH  1 faZH3 −1 −1 (5) and μWH=μZH1+f_aZH₃  ZH,WH−1  , (6) where ZH,WH= σ ZH 1 /σ3ZH σWH 1 /σ3WH . (7)

The σ1/σ3 ratiosgivenby the JHUGen 4.3[19,25,26]event gener-atorandvaluesof i,j aregiveninTables 1 and 2,respectively. Inordertoimprovethesensitivitytoanomalouscouplings,results fromtheVHchannelsarecombinedwiththosefromH→VV[15]. We assume the signal yield in the H→VV analysis to be dom-inated by gluon fusion production with negligible contamination fromvector boson fusion orVH production,as in Ref. [15]. Pro-vided that the ratio of the Hbb and Htt coupling strengths is givenbytheSM prediction,Eq.(6)can beusedtorelate the sig-nalstrengthintheVHandH→VV analyses,withanappropriate change of indices(replacing ‘WH’ with‘ZZ’ to relate the ZZ and ZH channels,or‘ZH’ with‘WW’ torelatethe WW andWH chan-nels).Inthecombinationofthe WHandH→WW channels,the ratioofthe signalstrengths μWH_/μWW _{increaseslinearlyfrom1} to173as f_aWW₃ increasesfrom0to1,accordingtoEq.(6).TheWH signal strength has beenmeasured by CMSto be 1.1±0.9 [23], andfor H→WW it has been measured to be 0.76±0.21 [13]. Thus,forintermediate andlargevaluesof fWW

a3 it isnotpossible

toreconcile theexpectedsignal yield withdatainboth channels simultaneously. A similar effect occurs in a combination of the ZHandH→ZZ channels,wherethe ratioofthesignal strengths

μZH_/μZZ_{risessharplywith f}ZZ a3.

However, an anomalous ratio of the Hbb and Htt coupling strengths spoilstherelationship inEq. (6). Wethereforeperform two interpretations ofthe VHandH→VV combination; one in-terpretationinwhich thisrelationshipisenforced,andone inter-pretation in which the signal strengths in the VH and H→VV channelsareallowedtovaryindependently. Thesearereferredto as the ‘correlated-μ’ and ‘uncorrelated-μ’ combinations, respec-tively.

Fig. 1. Feynmandiagramsrepresentinggluon-initiatedZHproductionviaaquark triangle(top)andbox(bottom)loop.

4. Simulation

Simulatedqq→VH signaleventsaregeneratedforpurescalar and pseudoscalar hypotheses with the leading-order (LO) event generator JHUGen,andassumingamassmH=125.6 GeV.The sim-ulatedeventsampleisreweightedbasedonthevectorbosonpT to includecorrectionsuptonext-to-next-to-LOandnext-to-LO(NLO) in theQCD andelectroweak (EW)couplingsrespectively [27–31]. ThesecorrectionsarederivedforascalarHiggsboson,andapplied tobothscalarandpseudoscalarsimulatedeventsamples.

The gg→ZH process includes diagrams with quark triangle and box loops, asshown in Fig. 1. These diagrams interfere de-structively with one another [32]. The box diagram contains no HVV vertex. The triangle diagram does, but is unaffected by the aHVV₃ terminEq.(1).The trianglediagram mediatedby aCP-odd HVV interaction is completely anti-symmetric underthe reversal ofthedirectionofloopmomentumflow;thediagramswith oppo-siteloop momentum flowtherefore perfectlycancelone another. As the aHZZ

1 coupling varies within a profile likelihood scan, the boxcontributionremainsfixedwhilethetrianglecontributionand the interferencemustbe variedaccordingly. Thisisaccomplished by reweighting thesimulated gg→ZH eventsample to havethe correctm(VH)distributionatthegenerator level,including inter-ference effects.Thisreweightingisbasedonresultsobtainedwith the VBFNLOeventgenerator [32,33],modified forthisanalysisto allowvariationoftheHff andHZZ couplingstrengths.

Simulatedbackgroundeventsamplesaregeneratedwitha va-rietyofeventgenerators.Diboson,W+jets,Z+jets,andtt samples are generated with MadGraph 5.1 [34], while powheg 1.0 [35] is used to generate single top quark samples, as well as the gluon-initiatedcontributiontoZHproduction(gg→ZH).The her-wig++ _{2.5 [36] generator is used along with alternative matrix} element generators to produce additional simulated background samplestoassessthesystematicuncertaintyrelatedtoevent sim-ulationaccuracy,asdescribedinSection6.

The pythia 6.4 [37]and herwig++ generatorsareusedto sim-ulateparton showeringandhadronization. Detectorsimulation is performed with Geant4 [38]. Uncorrelated proton–proton colli-sions occurring in the same bunch crossing as the signal event (pileup) are overlayed on top of the hard interaction, in accord withthedistributionobserved.Correctionsareappliedtothe sim-ulationinordertoaccountfordifferencesinobjectreconstruction efficienciesandresolutionswithrespecttothedata.

ControlregionsindataaredefinedinRef.[23],fromwhich nor-malizationscalefactorsforthedominantbackgroundsarederived. A simultaneousfit todata acrosscontrol regions is performedto extractthescalefactors,whichareappliedhere.Theshapeofthe W(V)bosontransversemomentumpT distributioniscorrectedin thesimulatedtt (V+jets)eventsample,basedonafittodataina background-enrichedcontrolregion.

5. Objectandeventselection

All objects are reconstructed using a particle-flow (PF) ap-proach[39,40].Amongallreconstructedprimaryverticessatisfying basic quality criteria, the vertex with the largest value of p2 T isselected.Electronsarereconstructedfrominnerdetectortracks matchedto calorimetersuperclusters, andselected witha multi-variateidentificationalgorithm[41].Electronsarerequiredtohave pT>30 GeV andpseudorapidity |η|<2.5,withavetoappliedto thebarrel-endcaptransitionregion(1.44<|η|<1.57)where elec-tronreconstruction issub-optimal.Muonsarereconstructedfrom innerdetectortracksmatchedtotracksreconstructedinthemuon system,andselectedwithacut-basedidentificationalgorithm[42]. Muons are required to have pT>20 GeV and |η|<2.4. Both electrons andmuonsare requiredto be well isolated fromother reconstructedobjects. Jetsare reconstructedusing theanti-kT al-gorithm [43], witha distance parameter of 0.5, fromthe recon-structedobjects, afterremoving chargedobjectswitha trajectory inconsistent withproduction at the primary vertex. Additionally, theenergycontributionfromneutralpileupactivityis subtracted withan area-based approach [44]. Jets are tagged as originating fromthe fragmentationandhadronization ofbottomquarkswith the combined secondary vertex (CSV) algorithm [45], which ex-ploitsboth the track impactparameter and secondary vertex in-formation.Missingtransverseenergy Emiss_T isreconstructedasthe negativevectorpTsumofallreconstructedobjects.

Events are categorized based on the flavour and number of charged leptons into four channels. Events with two same-flavour,opposite-signelectrons(muons)areassignedtotheZ→ee

(Z→μμ) channel. Events with one electron (muon) and large Emiss

T are assigned to the W→eν (W→μν) channel. In the

W→ ν (Z→ ) channels, Higgs boson candidates are

con-structed fromthe pairof jets(referred to asj1 and j2) withthe largest vector pT sum among jets with pT>30 (20) GeV and |η|<2.5.TheZbosoncandidatesareconstructedfromleptonpairs whoseinvariantmassisconsistentwiththeZbosonmass.TheW bosoncandidatesareconstructedbycombiningthemomentumof theidentifiedleptonwiththeeventEmiss

T ,andcalculatingthe neu-trinomomentumalong thebeamaxisbasedona W bosonmass constraint. To suppress contributions from QCD multijet events, inthe W→ ν channelsthemagnitude ofthe Emiss_T vector must exceed 45 GeV and it must be separated in direction from the chargedlepton bylessthan π/2 radiansin azimuth. Inaddition, theHiggsbosoncandidatepT mustexceed100 GeV.

The analysis sensitivity is increased further by categorizing events into medium- and high-boost regions based on the pT ofthe vector boson candidate. The bulk of thesensitivity comes fromthehigh-boostregion.Theseregionsare latercombined sta-tistically. In the W→ ν channels, the medium- and high-boost regions are defined by 130< pT(W)<180 GeV and pT(W)> 180 GeV,respectively.IntheZ→ channels, theregionsare in-steaddefinedby50<pT(Z)<100 GeV andpT(Z)>100 GeV.The low-boost region described in Ref. [23] is not included because ofits negligiblesensitivityto anomalouscouplings. Requirements onthe Higgs boson candidatemass and theb-tagging likelihood discriminants ofthe jetsused to construct the Higgsboson can-didateare also applied. The selection criteriaare summarized in Table 3.

The expected scalar, pseudoscalar, and total background tem-plates for the high-boost W→eν channel are shown in Fig. 2. One-dimensional projections of the templates for the high-boost W→μν and Z→ee channelsonto the m(VH) axis are shown inFig. 3. The discrimination power of m(VH) for the scalar and pseudoscalarhypothesescanbeseenclearly;thepseudoscalar

hy-Table 3

Summaryoftheeventselectioncriteria.Numbersinparenthesesrefertothe high-boostregiondefinedinthetext.

Variable W→ ν Z→  pT(j1)[GeV] >30 >20 pT(j2)[GeV] >30 >20 max(CSV(j1),CSV(j2)) >0.40 >0.50 (>0.244) min(CSV(j1),CSV(j2)) >0.40 >0.244 pT(H)[GeV] >100 – m(H)[GeV] <250 40–250 (<250) m(V)[GeV] – 75–105 pT(V)[GeV] 130–180 (>180) 50–100 (>100) Emiss T [GeV] >45 – (Emiss T , ) <π/2 – Table 4

Summaryofthesourcesofsystematicuncertaintyonthebackgroundandsignal yields.Thesizeoftheuncertaintiesthatonlyaffectnormalizationsaregiven. Un-certaintiesthatalsoaffecttheshapesareimplementedwithtemplatemorphing, asmoothverticalinterpolationbetweenthenominalshapeandsystematicshape variations.

Source Pre-fit uncertainty

Normalization uncertainties

Integrated luminosity 2.6%

Lepton reconstruction and trigger efficiency 3% per

Missing transverse energy scale and resolution 3% Signal and background cross section (scale) 4–6% Signal and background parton distribution functions 1%

0+(0−)EW/QCD signal corrections 2%/5% (10%/5%) tt and V+jets data-driven scale factors 10%

Single top quark cross section 15%

Diboson cross section 15%

gg→ZH cross section +₋35%25%

Normalization+shape uncertainties

Jet energy scale ±1σ

Jet energy resolution ±1σ

b tagging efficiency ±1σ

b tagging mistag rate ±1σ

Simulated event statistics ±1σ

Event simulation accuracy (V+jets and tt) Alternate event simulation m(VH)modeling ±2×fitted slope pothesistends toproducelarger valuesofm(VH)thanthe scalar hypothesis.

6. Systematicuncertainties

Avarietyofsources ofuncertaintyareconsideredinthis anal-ysis. These include the energy scale, energy resolution, and re-constructionefficienciesoftherelevantphysicsobjects;integrated luminosity determination; cross section and background normal-izationscalefactoruncertainties;andtheaccuracyandfinitesize ofthesimulatedeventsamples.Thetreatmentofmost uncertain-tiesisidenticalto thatofRef.[23],withtheexceptionsdiscussed below.AlluncertaintiesaresummarizedinTable 4.

Uncertaintiesareassignedtoboth thescalarandpseudoscalar signal yields, related to the calculation of higher-order QCD and EW corrections. In the pseudoscalar case, the uncertainty in the NLO EWcorrectionsistakento bethesize ofthecorrectionsfor ascalarHiggsboson.Aslightmismodelingofthem(VH) distribu-tionis observedinasidebandofthemedium-boost regions with valuesoftheBDT discriminantlessthan −0.3. Thissidebandhas negligiblesignalcontent.Theratioofdatatothebackground pre-diction hasanapproximatelyconstant, positiveslope.As aresult, anadditionalm(VH)modelingsystematicuncertaintyisincluded, whichallowsforalinearcorrectionofthebackgroundmodel.The sizeofthisuncertaintyistakenastwice theratioofdatato pre-diction,asfittedbyalinearfunctioninm(VH).

Fig. 2. Thescalar(left),pseudoscalar(right),andtotalbackground(bottom)templatesforthehigh-boostW→eν channel.Bincontentisnormalizedaccordingtothebin area.

Fig. 3. Them(VH)distributionsforthehigh-boostregionoftheW→μν(left)andZ→ee (right)channels.Thedistributionobservedindataisrepresentedbypointswith errorbars.SMbackgroundsarerepresentedbyfilledhistograms.Apurescalar(pseudoscalar)Higgsbosonsignalisrepresentedbythesolid(dotted)histogram.Thestatistical uncertaintyrelatedtothefinitesizeofthesimulatedbackgroundeventsamplesisrepresentedbythehatchedregion.Valuesofm(VH) >1200 GeV areincludedinthelast bin.Thebincontentisnormalizedaccordingtothebinwidth.Thelowerpanelshowstheratiooftheobservedandexpectedbackgroundyields.

7. Results

Results of one-dimensional profile likelihood scans in the VH channelsareshowninFig. 4,intermsof f_aZH₃ .Throughoutthe pa-per,expectedresultsarederivedfroman Asimovdataset[46]for apurescalarHiggsbosonwith μ =1.Thisdatasetrepresentsthe expectationforanSMHiggsbosonintheasymptoticlimitoflarge statistics.ThecombinedVHscanassumesaHWW_i =aHZZ_i .

Theexpected−2lnLvaluesreachaplateauabove f_aZH₃ ≈0.3, asaresultofthesmall σ1/σ3valuesintheVHchannels.Evenfor modestvaluesof fZH

a3 ,thetotalsignalcrosssection,andtherefore

them(VH)shape,isdominatedby thepseudoscalarcontribution.

Increasing fZH

a3 furtherhaslittleimpactonthem(VH)shape,and

thereforethelikelihood.

Basedontheavailabledata,theVHchannelsalonedonothave sufficient sensitivity to derive any constraint on fa3 at 95% CL.

Although there is some discrepancy between the expected and observed scans, all observed results are consistent with the SM predictionof fa3=0.Thisdiscrepancyisdrivenbyamodestexcess

(deficit) at high(low) values ofm(VH) in a selected number of background-depletedbinsinthehigh-boostZ→ee andW→μν

channels,whichisconsistentwiththeSMpredictionwithin statis-ticalandsystematicuncertainties.

Results fromtheVHchannelsare combinedwithresultsfrom the H→VV channels [15], with and without assuming the SM

Fig. 4. ResultsofprofilelikelihoodscansfortheWHandZHchannels,aswellasthe combination(VH).Thedotted(solid)linesshowtheexpected(observed)−2lnL valueasafunctionof fZH

a3. Ahorizontaldashed lineis shown,representingthe

68% CL.

ratiooftheHbb andHtt couplingstrengths.Combinedprofile like-lihoodscansareshowninFigs. 5 and 6,intermsof fZZ

a3 or f

WW a3 .

The−2lnLdistributionsshownherefortheVHchannelsalone arethesameasthoseshowninFig. 4,afteratransformationofthe x-axis to fWW

a3 or f

ZZ

a3. These transformations compress (stretch)

thelow(high) fa3 region,resultinginthedistributionsshown.The

positionofthe−2lnLminimaand fa3 confidenceintervalsare

giveninTable 5.

The WH (ZH) channel is first combined with the H→WW

(H→ZZ) channel, enhancing the sensitivityto anomalous HWW (HZZ) interactions, without the need to introduce any assump-tionontherelationshipbetweenHWWandHZZcouplings.These results are shown in the upper (lower) portion of Fig. 5. The H→WW channel alone is not able to constrain fa3 at 68% CL.

However, in the uncorrelated-μ combination of the WH and H→WW channels, fWW

a3 >0.21 is disfavoured at 68% CL. Due

to the modest preference in the ZH channel for large fa3, the

uncorrelated-μ combination ofthe ZH andH→ZZ channels re-sultsinaboundon fa3 thatisslightlyweaker thanthat fromthe

H→ZZ channelalone.

AllfourchannelsarecombinedundertheassumptionaHWW_i = aHZZ_i .Theresultsofthisuncorrelated-μcombinationareshownin

the top ofFig. 6.A slight improvementover the constraintfrom theH→VV channelsaloneisobserved,with f_aZZ₃ >0.25 excluded at95%CL.

Correlated-μ combinations of the VH and H→VV channels areperformedaswell, whicharebasedontheassumptionofthe SM ratioofthe Hbb andHtt coupling strengths.Thisassumption fixes therelationshipbetweenthesignalstrengths intheVHand H→VV channels.Asaresultoftherelativelywellmeasuredsignal strengthsintheH→VV channels, forintermediateandlarge val-uesof fa3 thesignalstrengthsintheVHchannelsareconstrained

tolargevalues,andsuchasignalcannotbeaccommodatedbythe data.TheresultsareshowninthebottomofFig. 6.Relativetothe fa3 exclusionsobtainedfromtheH→VV channelsalone,the

re-sults obtained here are significantly stronger, with fZZ

a3 >0.0034

excludedat95%CLinthefullcombinationofallchannels. ThefuturepoweroftheVHchannelsatprobingsmall anoma-lous HVV couplings is demonstrated on the right side of Figs. 5 and 6. Although the expected exclusion of anomalous couplings in these channels is only at the ∼68% CL level with the cur-rent 8 TeV dataset, the −2lnL values increase sharply for small, non-zero valuesof fZZ

a3 andreach a plateauat f

ZZ a3 ≈0.05.

Withthe inclusion of√s=13 TeV collision datafromthe ongo-ing LHC run, the shape of these −2lnLdistributions will not change significantly, but the plateau will reach larger values of −2lnL. As soon as the exclusion of a pure pseudoscalar be-comes possible,itwillbe possibletoexclude smallvaluesof f_aZZ₃ aswell.

Resultsoftwo-dimensional profilelikelihoodscansinthe μZH versus fZH

a3 planebasedonacombinationofWHandZHchannels

areshowninFig. 7.Smaller μZH_{valuesarepreferredwith} increas-ing fZH

a3 asaresultofincreasingsignalefficiency,duetotheharder

m(VH)distributionofapotentialpseudoscalarsignalcomparedto thatofascalar.Theminimumofthe−2lnLvaluescorresponds to μZH_{=1.11 and f}ZH

a3 =0.22.

Finally,weallowforthemodificationoftheaHVV₃ couplingsby amomentum-dependentformfactor[19],givenby

⎡ ⎣  1+q 2 V1 2 2 1+q 2 V2 2 2⎤ ⎦ −1 , (8)

where  represents a scale of new physics at which the aHVV₃ couplingcannolongerbetreatedasaconstant.Unlikeearlier re-sults in H→VV [15] wherethe vector boson q2 is restricted to 100 GeV, in VH production much larger values are accessible. This fact isresponsible for much ofthe sensitivityof this analy-sis, butalso necessitates the considerationof formfactor effects. ProfilelikelihoodscansbasedonacombinationoftheWHandZH channelsforvariousvaluesofareshowninFig. 8.

Table 5

Asummaryofthelocationsoftheminimum−2lnLvaluesinone-dimensional fa3 profilelikelihoodscans.Parenthesescontain68%CLintervals,andbracketscontain

95% CLintervals.Therangesaretruncatedatthephysicalboundaries0<fa3<1.TheresultsofcombinationswhichinvolvebothVHandH→VV channelsaregivenwith

andwithoutassumingtheSMratioofthecouplingstrengthsoftheHiggsbosontotopandbottomquarks.

Channel Parameter Expected Observed

VH fZH a3 0 (0, 0.64) [0, 1] 0.22 (0.029, 1) [0, 1] Correlated-μcombination WH+H→WW fWW a3 0 (0, 0.0012) [0, 0.0027] 0.0026 (0.00082, 0.0053) [0, 0.0098] ZH+H→ZZ fZZ a3 0 (0, 0.0014) [0, 0.0034] 0.0011 (0, 0.0029) [0, 0.0056] VH+H→VV fZZ a3 0 (0, 0.00050) [0, 0.0011] 0.0012 (0.00047, 0.0021) [0, 0.0034] Uncorrelated-μcombination WH+H→WW fWW a3 0 (0, 1) [0, 1] 0.00088 (0, 0.21) [0, 1] ZH+H→ZZ fZZ a3 0 (0, 0.21) [0, 0.66] 0.0067 (0, 0.16) [0, 0.44] VH+H→VV fZZ a3 0 (0, 0.0062) [0, 0.44] 0.0010 (0.00011, 0.043) [0, 0.25]

Fig. 5. ResultsofprofilelikelihoodscansfortheVHandVVchannels,plustheircombination.Thedotted(solid)linesshowtheexpected(observed)−2lnLvalueasa functionof fa3.Thefullrangeoffa3 isshownontheleft,withthelowfa3regionhighlightedontheright.Horizontaldashedlinesrepresentthe68%,95%,and99%CL.

For 10 TeV, a potential momentum-dependent form fac-torhasanegligibleimpactontheanalysis.Butforsmallervalues of,thetailofthe m(VH)distribution isdiminished,andalong withitthesensitivityto anomalouscouplings. However,even for

valuesassmallas1 TeV, theVHchannelsmaintainsignificant sensitivity.

8. Summary

Asearch hasbeenperformedforanomalouspseudoscalarHVV interactions in √s=8 TeV pp data collected with the CMS de-tector. This is the first study of such interactions at the LHC in associated VHproduction. The resultsbased on the VHchannels arecombinedstatisticallywiththosefromapreviously published study ofH→VV decays,whichassumesthesignal yieldis dom-inated by gluon fusion production of the Higgs boson. Channels sensitive tothe HWW andHZZ interaction are combined

assum-ing equality of the couplings of the Higgs boson to W and Z bosons.

A leading order scalar aHVV₁ and pseudoscalar aHVV₃ coupling with a relative phase of 0 are considered, while all other po-tential tensor structures are neglected. The aHVV

1 and aHVV3 cou-plings are first treated asconstants, but later modified to allow potentialmomentum-dependentformfactoreffectsinVH produc-tion. Profile-likelihood scans are used to assess the consistency ofthedata withvarious effectivepseudoscalarcrosssection frac-tions, fa3.

TheVHchannelsalonedonotcurrentlyhavesufficient sensitiv-itytoconstrainthe fa3 at95%CL.However, f

ZZ

a3 canbeconstrained

tothesub-percentlevelinacombinationofVHandH→VV chan-nels, when assuming the standard model ratio of the coupling strengthsoftheHiggsbosontotopandbottomquarks.Underthis assumption, andignoring formfactoreffects, faZZ3 >0.0034 is

Fig. 6. ResultsofprofilelikelihoodscansfortheVHandVVchannels,aswellastheircombination.Thedotted(solid)linesshowtheexpected(observed)−2lnLvalueas afunctionof fa3.Thefullrangeof fa3 isshownontheleft,withthelow fa3 regionhighlightedontheright.Thebottomplotscontaintheresultsofcorrelated-μscans.

Horizontaldashedlinesrepresentthe68%,95%,and99%CL.Inthelegend,VHreferstothecombinationoftheWHandZHchannels,andVVreferstothecombinationof theH→WW andH→ZZ channels.

Acknowledgements

We would like to thank Christoph Englert, Matthew McCul-lough, and Michael Spannowsky for providing calculations of gg→ZH kinematicswithnon-SMcouplings.We especiallythank Christophforhishelp inunderstanding the symmetry considera-tionsatworkinthisprocess.

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 effectivelythecomputinginfrastructure essential toour analyses. Finally, we acknowledge the enduring support for the

construc-tionandoperation oftheLHC andtheCMSdetectorprovidedby thefollowingfundingagencies:BMWFWandFWF(Austria);FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES(Bulgaria);CERN;CAS,MoST,andNSFC(China);COLCIENCIAS (Colombia);MSESandCSF(Croatia);RPF(Cyprus);MoER,ERCIUT andERDF(Estonia);Academy ofFinland,MEC,andHIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT,SEP,andUASLP-FAI(Mexico);MBIE(NewZealand);PAEC (Pakistan);MSHEandNSC (Poland);FCT(Portugal);JINR(Dubna); MON,RosAtom,RASandRFBR(Russia);MESTD(Serbia);SEIDIand CPAN(Spain);SwissFundingAgencies(Switzerland);MST(Taipei); ThEPCenter,IPST, STARandNSTDA(Thailand);TUBITAKandTAEK

Fig. 7. Expected(left)and observed(right)two-dimensionalprofilelikelihoodscansbasedonacombinationoftheWHandZHchannelsinthe fZH

a3 versusμ

ZH_plane.

Thecolourcodingrepresents−2lnLcalculatedwithrespecttotheglobalminimum.Thescanminimumisindicatedbyawhitedot.The68%and95%CLcontoursat −2lnL=2.30 and5.99,respectively,areshown.Theobservedresultincludesupperandlowerboundswhiletheexpectedresultcontainsonlyupperbounds,asthe expectedresultisconsistentwith fZH

a3 =0 at68%CL.(Forinterpretationofthereferencestocolourinthisfigurelegend,thereaderisreferredtothewebversionofthis

article.)

Fig. 8. Resultsofexpected(left)andobserved(right) fZH

a3 scansbasedonacombinationoftheWHandZHchannels,withvariousscalesofnewphysics.Thecoloured

linesshowthe−2lnLvalueasafunctionoffZH

a3.Thehorizontaldashedlinerepresentsthe68%CL.(Forinterpretationofthereferencestocolourinthisfigurelegend,the

readerisreferredtothewebversionofthisarticle.)

(Turkey);NASUandSFFR(Ukraine); STFC(United Kingdom);DOE andNSF(USA).

Individuals have received support from the Marie-Curie pro-grammeandthe European ResearchCouncil andEPLANET (Euro-peanUnion);theLeventisFoundation;theAlfredP.Sloan Founda-tion; the Alexander von Humboldt Foundation; the Belgian Fed-eral Science Policy Office; the Fonds pour la Formation à la Recherchedansl’Industrieetdansl’Agriculture (FRIA-Belgium);the AgentschapvoorInnovatiedoorWetenschapenTechnologie (IWT-Belgium);the Ministry ofEducation,Youth andSports (MEYS) of theCzechRepublic;theCouncilofScienceandIndustrialResearch, India; the HOMING PLUS programme of the Foundation for Pol-ish Science, cofinanced from European Union, Regional Develop-ment Fund; the OPUS programme of the National Science Cen-tre (Poland); theCompagnia di SanPaolo (Torino); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes cofi-nancedbyEU-ESF andtheGreek NSRF;theNationalPriorities

Re-searchProgrambyQatarNationalResearchFund;theRachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn Univer-sity (Thailand);theChulalongkornAcademic intoIts 2nd Century Project Advancement Project (Thailand); and the Welch Founda-tion,contractC-1845.

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CMSCollaboration

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

W. Adam, E. Asilar,T. Bergauer, J. Brandstetter, E. Brondolin,M. Dragicevic, J. Erö,M. Flechl, M. Friedl,

R. Frühwirth1,V.M. Ghete, C. Hartl, N. Hörmann, J. Hrubec, M. Jeitler1, V. Knünz,A. König,

M. Krammer1,I. Krätschmer, D. Liko,T. Matsushita, I. Mikulec,D. Rabady2, N. Rad, B. Rahbaran,

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

InstitutfürHochenergiephysikderOeAW,Wien,Austria

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

NationalCentreforParticleandHighEnergyPhysics,Minsk,Belarus

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

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

UniversiteitAntwerpen,Antwerpen,Belgium

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

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

G.P. Van Onsem,I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

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

A. Grebenyuk,G. Karapostoli, T. Lenzi,A. Léonard,T. Maerschalk, A. Marinov, L. Perniè, A. Randle-Conde,

T. Seva, C. Vander Velde, P. Vanlaer,R. Yonamine, F. Zenoni, F. Zhang3

UniversitéLibredeBruxelles,Bruxelles,Belgium

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

A.A. Ocampo Rios, D. Poyraz,D. Ryckbosch, S. Salva, M. Sigamani, M. Tytgat,W. Van Driessche,

E. Yazgan, N. Zaganidis

GhentUniversity,Ghent,Belgium

S. Basegmez, C. Beluffi4,O. Bondu,S. Brochet, G. Bruno, A. Caudron, L. Ceard, C. Delaere, D. Favart,

L. Forthomme,A. Giammanco5,A. Jafari, P. Jez, M. Komm,V. Lemaitre, A. Mertens, M. Musich,

C. Nuttens, L. Perrini, K. Piotrzkowski,A. Popov6,L. Quertenmont, M. Selvaggi, M. Vidal Marono

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

N. Beliy, G.H. Hammad

UniversitédeMons,Mons,Belgium

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

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

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

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

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

D. Matos Figueiredo, C. Mora Herrera,L. Mundim, H. Nogima,W.L. Prado Da Silva, A. Santoro,

A. Sznajder,E.J. Tonelli Manganote7, A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

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

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

J.C. Ruiz Vargas

a_{UniversidadeEstadualPaulista,SãoPaulo,Brazil} b

A. Aleksandrov, R. Hadjiiska,P. Iaydjiev, M. Rodozov, S. Stoykova, G. Sultanov, M. Vutova

InstituteforNuclearResearchandNuclearEnergy,Sofia,Bulgaria

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

UniversityofSofia,Sofia,Bulgaria

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

F. Romeo,S.M. Shaheen, A. Spiezia,J. Tao, C. Wang, Z. Wang, H. Zhang

InstituteofHighEnergyPhysics,Beijing,China

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

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

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

UniversidaddeLosAndes,Bogota,Colombia

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

UniversityofSplit,FacultyofElectricalEngineering,MechanicalEngineeringandNavalArchitecture,Split,Croatia

Z. Antunovic,M. Kovac

UniversityofSplit,FacultyofScience,Split,Croatia

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

InstituteRudjerBoskovic,Zagreb,Croatia

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

UniversityofCyprus,Nicosia,Cyprus

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

CharlesUniversity,Prague,CzechRepublic

Y. Assran11,12, S. Elgammal11,A. Ellithi Kamel13,M.A. Mahmoud14

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

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

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,J. Pekkanen, M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

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

T. Peltola,E. Tuominen, J. Tuominiemi,E. Tuovinen, L. Wendland

HelsinkiInstituteofPhysics,Helsinki,Finland

J. Talvitie,T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon,F. Couderc, M. Dejardin, D. Denegri,B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour,

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

A. Rosowsky,M. Titov, A. Zghiche

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

N. Filipovic,R. Granier de Cassagnac, M. Jo,S. Lisniak, L. Mastrolorenzo, P. Miné, I.N. Naranjo,M. Nguyen,

C. Ochando, G. Ortona,P. Paganini, P. Pigard, S. Regnard, R. Salerno,J.B. Sauvan, Y. Sirois, T. Strebler,

Y. Yilmaz,A. Zabi

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

J.-L. Agram15, J. Andrea, A. Aubin, D. Bloch,J.-M. Brom, M. Buttignol,E.C. Chabert, N. Chanon, C. Collard,

E. Conte15, X. Coubez, J.-C. Fontaine15,D. Gelé, U. Goerlach,C. Goetzmann, A.-C. Le Bihan, J.A. Merlin2,

K. Skovpen, P. Van Hove

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

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,C. Bernet, G. Boudoul, E. Bouvier, C.A. Carrillo Montoya, R. Chierici,D. Contardo,

B. Courbon, P. Depasse, H. El Mamouni, J. Fan, J. Fay, S. Gascon, M. Gouzevitch, B. Ille, F. Lagarde,

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

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

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

T. Toriashvili16

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze10

TbilisiStateUniversity,Tbilisi,Georgia

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

F. Raupach, S. Schael, J.F. Schulte,T. Verlage, H. Weber, V. Zhukov6

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

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

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

A. Meyer, P. Millet,S. Mukherjee, M. Olschewski, K. Padeken,P. Papacz, T. Pook,M. Radziej, H. Reithler,

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

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

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

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

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,I. Asin, N. Bartosik, O. Behnke, U. Behrens,K. Borras17,A. Burgmeier, A. Campbell,

C. Contreras-Campana, F. Costanza, C. Diez Pardos,G. Dolinska, S. Dooling,T. Dorland, G. Eckerlin,

D. Eckstein, T. Eichhorn, G. Flucke, E. Gallo18,J. Garay Garcia, A. Geiser, A. Gizhko, P. Gunnellini, J. Hauk,

M. Hempel19,H. Jung, A. Kalogeropoulos, O. Karacheban19, M. Kasemann,P. Katsas, J. Kieseler,

C. Kleinwort,I. Korol, W. Lange, J. Leonard,K. Lipka, A. Lobanov, W. Lohmann19,R. Mankel,

I.-A. Melzer-Pellmann,A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, S. Naumann-Emme,A. Nayak,

E. Ntomari,H. Perrey, D. Pitzl,R. Placakyte, A. Raspereza, B. Roland,M.Ö. Sahin, P. Saxena,

T. Schoerner-Sadenius,C. Seitz, S. Spannagel, K.D. Trippkewitz, R. Walsh, C. Wissing

DeutschesElektronen-Synchrotron,Hamburg,Germany

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

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

D. Rathjens,C. Sander, C. Scharf, P. Schleper, E. Schlieckau, A. Schmidt, S. Schumann,J. Schwandt,

V. Sola,H. Stadie, G. Steinbrück, F.M. Stober,H. Tholen, D. Troendle,E. Usai, L. Vanelderen, A. Vanhoefer,

B. Vormwald

UniversityofHamburg,Hamburg,Germany

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

A. Dierlamm,S. Fink, F. Frensch, R. Friese,M. Giffels, A. Gilbert,D. Haitz, F. Hartmann2,S.M. Heindl,

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

Th. Müller, M. Plagge, G. Quast, K. Rabbertz,S. Röcker, F. Roscher,M. Schröder, G. Sieber, H.J. Simonis,

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

InstitutfürExperimentelleKernphysik,Karlsruhe,Germany

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

I. Topsis-Giotis

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

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

NationalandKapodistrianUniversityofAthens,Athens,Greece

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

J. Strologas

UniversityofIoánnina,Ioánnina,Greece

G. Bencze,C. Hajdu, A. Hazi,P. Hidas, D. Horvath20, F. Sikler,V. Veszpremi, G. Vesztergombi21,

A.J. Zsigmond

WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni,S. Czellar, J. Karancsi22,J. Molnar, Z. Szillasi2

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

M. Bartók23,A. Makovec,P. Raics, Z.L. Trocsanyi, B. Ujvari

UniversityofDebrecen,Debrecen,Hungary

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

NationalInstituteofScienceEducationandResearch,Bhubaneswar,India

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

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

PanjabUniversity,Chandigarh,India

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

R. Sharma,V. Sharma

UniversityofDelhi,Delhi,India

S. Bhattacharya, K. Chatterjee,S. Dey, S. Dutta, N. Majumdar, A. Modak, K. Mondal, S. Mukhopadhyay,

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

SahaInstituteofNuclearPhysics,Kolkata,India

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

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

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

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

TataInstituteofFundamentalResearch,Mumbai,India

S. Chauhan,S. Dube, A. Kapoor, K. Kothekar, S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

H. Bakhshiansohi,H. Behnamian, S.M. Etesami28, A. Fahim29, M. Khakzad, M. Mohammadi Najafabadi,

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

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, C. Calabriaa,b,C. Caputoa,b,A. Colaleoa,D. Creanzaa,c, L. Cristellaa,b,N. De Filippisa,c, M. De Palmaa,b, L. Fiorea,G. Iasellia,c, G. Maggia,c,M. Maggia, G. Minielloa,b, S. Mya,c, S. Nuzzoa,b, A. Pompilia,b,G. Pugliesea,c,R. Radognaa,b,A. Ranieria,G. Selvaggia,b,L. Silvestrisa,2, R. Vendittia,b a_{INFNSezionediBari,Bari,Italy}

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

G. Abbiendia,C. Battilana2, A.C. Benvenutia,D. Bonacorsia,b,S. Braibant-Giacomellia,b, L. Brigliadoria,b, R. Campaninia,b, P. Capiluppia,b,A. Castroa,b,F.R. Cavalloa, S.S. Chhibraa,b, G. Codispotia,b,

M. Cuffiania,b,G.M. Dallavallea,F. Fabbria,A. Fanfania,b,D. Fasanellaa,b,P. Giacomellia, C. Grandia, L. Guiduccia,b,S. Marcellinia,G. Masettia,A. Montanaria,F.L. Navarriaa,b, A. Perrottaa,A.M. Rossia,b, T. Rovellia,b,G.P. Sirolia,b,N. Tosia,b,2,R. Travaglinia,b

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

G. Cappelloa,M. Chiorbolia,b,S. Costaa,b,A. Di Mattiaa, F. Giordanoa,b,R. Potenzaa,b, A. Tricomia,b, C. Tuvea,b

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

G. Barbaglia, V. Ciullia,b,C. Civininia, R. D’Alessandroa,b,E. Focardia,b,V. Goria,b, P. Lenzia,b, M. Meschinia, S. Paolettia,G. Sguazzonia,L. Viliania,b,2

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

L. Benussi, S. Bianco, F. Fabbri,D. Piccolo, F. Primavera2

INFNLaboratoriNazionalidiFrascati,Frascati,Italy

V. Calvellia,b, F. Ferroa, M. Lo Veterea,b, M.R. Mongea,b,E. Robuttia,S. Tosia,b a_{INFNSezionediGenova,Genova,Italy}

b_{UniversitàdiGenova,Genova,Italy}

L. Brianza,M.E. Dinardoa,b, S. Fiorendia,b,S. Gennaia,R. Gerosaa,b,A. Ghezzia,b, P. Govonia,b,

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

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

S. Buontempoa, N. Cavalloa,c,S. Di Guidaa,d,2, M. Espositoa,b, F. Fabozzia,c,A.O.M. Iorioa,b, G. Lanzaa, L. Listaa,S. Meolaa,d,2,M. Merolaa,P. Paoluccia,2,C. Sciaccaa,b,F. Thyssen

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

P. Azzia,2,N. Bacchettaa,L. Benatoa,b, D. Biselloa,b, A. Bolettia,b, A. Brancaa,b,R. Carlina,b,P. Checchiaa, M. Dall’Ossoa,b,2,T. Dorigoa, U. Dossellia,F. Fanzagoa,F. Gasparinia,b,U. Gasparinia,b, A. Gozzelinoa, K. Kanishcheva,c,S. Lacapraraa, M. Margonia,b, A.T. Meneguzzoa,b,J. Pazzinia,b,2, N. Pozzobona,b, P. Ronchesea,b,F. Simonettoa,b, E. Torassaa, M. Tosia,b, M. Zanetti,P. Zottoa,b, A. Zucchettaa,b,2,

G. Zumerlea,b

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

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

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

L. Alunni Solestizia,b, G.M. Bileia,D. Ciangottinia,b,2, L. Fanòa,b,P. Laricciaa,b,G. Mantovania,b,

M. Menichellia,A. Sahaa,A. Santocchiaa,b

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

K. Androsova,31,P. Azzurria,2,G. Bagliesia, J. Bernardinia,T. Boccalia,R. Castaldia, M.A. Cioccia,31, R. Dell’Orsoa,S. Donatoa,c,2, G. Fedi,L. Foàa,c,†,A. Giassia, M.T. Grippoa,31, F. Ligabuea,c,T. Lomtadzea, L. Martinia,b,A. Messineoa,b,F. Pallaa, A. Rizzia,b, A. Savoy-Navarroa,32, A.T. Serbana,P. Spagnoloa, R. Tenchinia,G. Tonellia,b, A. Venturia,P.G. Verdinia

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

c_{ScuolaNormaleSuperiorediPisa,Pisa,Italy}

L. Baronea,b, F. Cavallaria,G. D’imperioa,b,2, D. Del Rea,b,2, M. Diemoza,S. Gellia,b, C. Jordaa,

E. Longoa,b, F. Margarolia,b, P. Meridiania,G. Organtinia,b, R. Paramattia,F. Preiatoa,b, S. Rahatloua,b, C. Rovellia,F. Santanastasioa,b,P. Traczyka,b,2

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

N. Amapanea,b,R. Arcidiaconoa,c,2,S. Argiroa,b,M. Arneodoa,c,R. Bellana,b, C. Biinoa, N. Cartigliaa, M. Costaa,b, R. Covarellia,b, A. Deganoa,b,N. Demariaa,L. Fincoa,b,2,B. Kiania,b, C. Mariottia,S. Masellia, E. Migliorea,b,V. Monacoa,b, E. Monteila,b,M.M. Obertinoa,b,L. Pachera,b,N. Pastronea, M. Pelliccionia, G.L. Pinna Angionia,b,F. Raveraa,b,A. Romeroa,b,M. Ruspaa,c, R. Sacchia,b, A. Solanoa,b, A. Staianoa a_{INFNSezionediTorino,Torino,Italy}

b_{UniversitàdiTorino,Torino,Italy}

c_{UniversitàdelPiemonteOrientale,Novara,Italy}

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

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

A. Kropivnitskaya,S.K. Nam

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

KyungpookNationalUniversity,Daegu,RepublicofKorea

J.A. Brochero Cifuentes, H. Kim,T.J. Kim

ChonbukNationalUniversity,Jeonju,RepublicofKorea

S. Song

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

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

KoreaUniversity,Seoul,RepublicofKorea

H.D. Yoo

SeoulNationalUniversity,Seoul,RepublicofKorea

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

UniversityofSeoul,Seoul,RepublicofKorea

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

SungkyunkwanUniversity,Suwon,RepublicofKorea

V. Dudenas, A. Juodagalvis,J. Vaitkus

VilniusUniversity,Vilnius,Lithuania

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

M.N. Yusli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

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

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

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, F. Vazquez Valencia

UniversidadIberoamericana,MexicoCity,Mexico

I. Pedraza, H.A. Salazar Ibarguen

BenemeritaUniversidadAutonomadePuebla,Puebla,Mexico

A. Morelos Pineda

UniversidadAutónomadeSanLuisPotosí,SanLuisPotosí,Mexico

D. Krofcheck

UniversityofAuckland,Auckland,NewZealand

P.H. Butler

UniversityofCanterbury,Christchurch,NewZealand

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