Search for an exotic decay of the Higgs boson to a pair of light pseudoscalars in the final state with two muons and two b quarks in pp collisions at 13 TeV

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

an

exotic

decay

of

the

Higgs

boson

to

a

pair

of

light

pseudoscalars

in

the

final

state

with

two

muons

and

two

b quarks

in

pp collisions

at

13 TeV

.TheCMS Collaboration CERN,Switzerland a r t i c l e i n f o a b s t ra c t Articlehistory: Received15December2018 Receivedinrevisedform2May2019 Accepted11June2019

Availableonline13June2019 Editor:M.Doser

Keywords:

CMS Physics

BSMHiggsphysics

AsearchforexoticdecaysoftheHiggsbosontoapairoflightpseudoscalarparticlesa1isperformed under the hypothesis thatone ofthepseudoscalars decays toapairofoppositesign muonsand the other decays to bb.Such signatures are predicted in anumber ofextensions ofthe standard model (SM),includingnext-to-minimalsupersymmetryandtwo-Higgs-doubletmodelswithanadditionalscalar singlet.The resultsare basedonadata setofproton-protoncollisionscorresponding toanintegrated luminosityof35.9 fb−1,accumulatedwiththeCMSexperimentattheCERNLHCin2016ata centre-of-massenergyof13 TeV.NostatisticallysignificantexcessisobservedwithrespecttotheSMbackgrounds in the searchregion for pseudoscalar massesfrom 20 GeV to half of the Higgs boson mass. Upper limits at95% confidence level are set on the productof the productioncross sectionand branching fraction, σhB(h→a1a1→μ+μ−bb),ranging from5 to 33 fb,depending onthe pseudoscalarmass. Correspondinglimitsonthebranchingfraction,assumingtheSMpredictionforσh,are(1–7)×10−4_.

©2019TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

The discovery of the particle now identified asthe Higgs bo-sonbytheATLASandCMSexperiments [1–3] attheCERNLHC [4] has opened a new era in the history of particle physics. So far, precisemeasurements oftheHiggsbosonspin,parity,width, and couplingsinproductionanddecayhavebeenconsistentwiththe expectationsforthestandardmodel(SM)Higgsboson [5–8]. How-ever, the possibility of exoticHiggs boson decays to new lighter bosonsisnotexcluded,andisproposedinvarioustheoriesbeyond the SM (BSM) [9]. The LHC combination of the SM Higgs boson measurements at7 and8 TeV allows Higgsbosondecaysto BSM stateswith a rateof up to 34% [7] at 95% confidence level (CL). The LHC dataat 13 TeVhave beenused to placean upperlimit ofabout 40% forthe Higgsboson branching fraction(B) to BSM particlesat95%CL [10].

Several searches for exotic decays of the Higgs boson have beenperformedattheLHC, usingthedataat8 TeV [11–14] and 13 TeV [15–21]. Such decays occur in the context of the next-to-minimal supersymmetric standard model, NMSSM, and other extensionsto two-Higgs-doubletmodels (2HDM) wherethe

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

tenceofascalarsingletishypothesised(2HDM+S) [9,22–24]. The 2HDM, and hence 2HDM+S, are categorised into four types de-pendingontheinteractionofSMfermionswiththeHiggsdoublet structure [14]. All SM particles couple to thefirst Higgs doublet, 1,intypeImodels.IntypeIImodels,whichincludetheNMSSM,

up-typequarkscoupleto1 whileleptons anddown-typequarks

coupletothesecond Higgsdoublet,2.Quarkscoupleto1 and

leptons coupleto 2 in type III models. Intype IVmodels,

lep-tons and up-type quarks couple to 1, while down-type quarks

couple to 2. After electroweak symmetry breaking, the 2HDM

predictsapairofchargedHiggsbosonsH±,aneutralpseudoscalar A,andtwoneutralscalarmasseigenstates,H andh.Inthe decou-pling limit the lighter scalareigenstate, h, isthe observed boson withmh≈125 GeV.In2HDM+S models,acomplex scalarsinglet

SR+i SIthathasnodirectYukawacouplingsisintroduced.Hence,

itisexpectedtodecaytoSMfermionsbyvirtueofmixingwiththe Higgssector. ThismixingissmallenoughtopreservetheSM-like natureoftheh boson.

In thisLetter we consider theHiggs boson decayto a pairof a1 particles where a1 is a pseudoscalar mass eigenstate mostly

composed of SI. We perform a search for the decay chain h→

a1a1→μ+μ−bb. The gluon gluon fusion (ggF) and the vector

boson fusion (VBF) production mechanisms are considered, with production cross sectionsof 48.58±2.45 pb (at

next-to-next-to-https://doi.org/10.1016/j.physletb.2019.06.021

0370-2693/©2019TheAuthor(s).PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).Fundedby SCOAP3_.

next-to-leading order in QCD) and 3.78±0.08 pb (at next-to-next-to-leadingorderinQCD),respectively [25]. As abenchmark, the branching fraction of h→a1a1 is assumed to be 10%. The

branching fractions of a1 to SM particles depend on the type of

2HDM+S, on the pseudoscalar mass ma1, and on tanβ, defined astheratio ofthe vacuumexpectationvaluesof thesecond and firstdoublets.Thetanβ parameterisassumedtobe2 which im-plies2B(a1→bb)B(a1→μ+μ−)=1.7×10−3 forma1=30 GeV intype-III2HDM+S [9].Forthesetofparametersunderdiscussion andwith 20≤ma1≤62.5 GeV, no strong dependenceon ma1 is expectedforB(a1→bb)andB(a1→μ+μ−)[9]. Theproductof

thecrosssectionandbranchingfractionisthereforeapproximated tobeabout8 fb forallma1 valuesconsideredinthisanalysis.

Thepresentsearchfortheexotica1particleinthe μ+μ−bb

fi-nal state is sensitive to the mass range of 20≤ma1≤62.5 GeV. The sensitivity of the search largely decreases towards ma1 ≈ 20 GeV and lower becausea1 gets boostedandthe two b quark

jetstendtomerge [26].TheupperboundisimposedbytheHiggs bosonmass.Theanalysisisperformedusingtheproton-proton col-lisiondataat13 TeVcollectedwiththeCMSdetectorduring2016, corresponding to an integrated luminosity of 35.9 fb−1. Though the signal selection is optimised for the h→a1a1→μ+μ−bb

process,decaysofh→a1a1→μ+μ−τ+τ−can contributetothe

selectedsample ifhadronically decaying τ leptons are misidenti-fiedasb quarkjets. Sucha contributionisfoundtobe negligible usingthebenchmarkscenario, althoughinsome partsof the pa-rameterspacethe enhancement in B(a1→τ+τ−) can lead to a

nonnegligiblefractionoftheseeventssurvivingtheselection.This istakenintoaccountinthescanoverthe(ma1,tanβ)planeinthe typeIII2HDM+S,asforcertainvalues,theincreasein μ+μ−τ+τ− signal canaffect thesensitivity. The signal froma1a1→bbτ+τ−

with τ→μ leads to mμμ significantly smaller than ma1 andis notconsideredinthesearch.

The CMS detector is briefly described in Section 2. The data andsimulated samples are introduced in Section 3. Section 4 is devotedto theeventselection andcategorisation. The signal and backgroundmodellingisdiscussedinSection5,whileinSection6, differentsourcesofsystematicuncertaintiesaredescribed.Results arepresented inSection 7, andthe paperis summarisedin Sec-tion8.

2. TheCMSdetector

The central feature of the CMS apparatus is a superconduct-ingsolenoidof 6 minternal diameter,providing amagnetic field of3.8 T.Withinthesolenoidvolumeare asilicon pixelandstrip tracker, a lead tungstate crystal electromagnetic calorimeter,and a brass and scintillator hadron calorimeter, each composed of a barrel and endcap sections. Forward calorimeters, made of steel and quartz-fibres, extend the pseudorapidity coverage provided by the barrel and endcap detectors. Muons are detected in gas-ionisationchambersembedded in thesteel flux-returnyoke out-sidethesolenoid. Theyare measuredinthepseudorapidityrange |η|<2.4, with detection planes made using three technologies: drifttubes, cathodestrip chambers, andresistiveplatechambers. The efficiency to reconstruct and identify muonsis greater than 96%.Matchingmuonstotracksmeasuredinthesilicontracker re-sultsinarelativetransversemomentum(pT)resolution,formuons

with pT up to 100 GeV, of1% inthe barrel and 3% in the

end-caps [27]. A more detailed description of the CMS detector, to-gether with a definition of the coordinate system used and the relevantkinematicvariables,canbefoundinRef. [28].

3. Simulatedsamples

The NMSSMHET model [9] is used togenerate signal samples withtheMonteCarlo(MC)eventgenerator MadGraph5_amc@nlo [29] atleadingorder(LO).Thesignalsamplesspanthema1 search region in5 GeVsteps.Background processeswithdominant con-tributions are the Drell–Yanproduction inassociation with addi-tional b quarksandtt in thedimuon final state. Simulated sam-ples for background processes are used in this analysis to op-timise the selection and for validation purposes in those selec-tionstepsthat yieldreasonablestatisticalprecision. The contribu-tion of backgrounds to the selected sample is directly extracted fromdatawithnoreferencetosimulation.TheDrell–Yanprocess, Z/γ∗(→ + −)+jets withaminimumdileptonmassthresholdof 10 GeV,ismodelledwiththesameeventgeneratoratLO,exclusive innumberofadditionalpartons(upto4).Thereferencecross sec-tionfortheDrell–Yanprocessiscomputedusing fewz 3.1 [30] at next-to-next-to-leading order.The top quark samples, tt and sin-gle top quark production,are produced with powheg2.0 [31–34] at next-to-leadingorder (NLO). Backgrounds fromdiboson (WW, WZ,ZZ)productionaregeneratedatNLOwiththesameprogram andsettingsasthatoftheDrell–Yansamples.Theonlyexception istheWW processthatisgeneratedatLO.Thesetofparton distri-butionfunctions(PDFs)isNLONNPDF3.0forNLOsamples,andLO NNPDF3.0forLOsamples [35].Forall samples, pythia 8.212 [36] withtuneCUETP8M1 [37,38] isusedforthemodellingofthe par-tonshoweringandfragmentation.ThefullCMSdetectorsimulation basedon Geant4 [39] isimplementedforallgeneratedevent sam-ples. In order to model the effect of additional interactions per bunchcrossing(pileup),generatedminimumbiaseventsareadded to the simulated samples. The number of additional interactions arescaledtoagreewiththatobservedindata [40].

4. Eventselectionandcategorisation

Eventsarefilteredusingahigh-leveltriggerrequirementbased onthepresenceoftwomuonswithpT>17 and8 GeV.Foroffline

selection, events must contain at least one primary vertex, con-sideredasthe vertexofthe hard interaction.At leastfourtracks must be associated withthe selected primary vertex. The longi-tudinal andradial distances of thevertex fromthe centreof the detectormustbesmallerthan24and2 cm,respectively.The ver-texwiththelargestsumofp2_T ofthephysicsobjectsischosenfor the analysis. The physics objectsare the jets, clusteredusingthe jet findingalgorithm [41,42] with thetracks assignedtothe ver-tex asinputs, andthe associated missing transverse momentum, takenasthenegativevectorsumofthe pT ofthosejets.Extra

se-lectioncriteriaareappliedtoleptonsandjets,reconstructedusing theCMSparticle-flowalgorithm [43].

Theselectionrequirestwomuonswithoppositeelectriccharge in |η|<2.4,originatingfromthe selectedprimary vertex. Events withtheleading (subleading)muon pT>20(9)GeV are selected.

ArelativeisolationvariableIreliscalculatedbysummingthe

trans-verse energy deposited by other particles inside a cone of size R=√(η)2+ (φ)2=0.4 aroundthemuon withφ beingthe azimuthalanglemeasuredinradians,dividedbythemuon pT,

Irel=

Ich. h+max((Iγ+In. h−0.5 IPU ch. h),0)

pT

, (1)

where Ich. h, Iγ , In. h and IPU ch. h are, respectively, the scalar pT

sums of stable charged hadrons, photons, neutral hadrons, and chargedhadronsassociatedwithpileupvertices.The contribution 0.5IPU ch. haccountsfortheexpectedpileupcontributionfrom neu-tral particles.The neutral-to-charged particle ratiois takento be

approximately 0.5from isospin invariance.Only muons withthe isolationvariablesatisfyingIrel<0.15 areconsideredinthe

analy-sis.Theefficienciesformuontrigger,reconstruction,andselection insimulatedeventsare correctedtomatchthosein data.Incase moremuonsintheeventpasstheselectionrequirements,thetwo withthelargest pTarechosen.

Jets are reconstructed by clustering charged and neutral par-ticlesusing theanti-kT algorithm [41] with a distanceparameter

of0.4. The reconstructed jet energy iscorrected for effects from the detector response as a function of the jet pT and η.

Con-taminationfrompileup,underlyingevent,andelectronicnoiseare subtracted [44,45]. Extra η-dependent smearing is performedon thejetenergyinsimulatedeventsasprescribedinRefs. [44,45].

Events are required to have at least two jets with |η|<2.4 and pT>20 (leading) and 15 GeV (subleading), with both jets

separatedfromthe selectedmuons (R>0.5). A combined sec-ondaryvertexalgorithm isused toidentifyjetsthat are likelyto originate fromb quarks. Thealgorithm uses the track-based life-time informationtogether with thesecondary vertices insidethe jettoprovideamultivariatediscriminator fortheb jet identifica-tion [46]. Working points “loose” (L), “medium”(M), and “tight” (T) are defined. They correspond to thresholds on the discrimi-nator,forwhich themisidentificationprobability is around10, 1, and 0.1%, respectively, for jets originating from light quarks and gluons [46]. The misidentification probability for jets originating fromc quarksisaround30,10,and2%,respectively,fortheloose, medium, and tight working points. The efficiencies for correctly identifying b jetsare ≈80%for theloose,≈60% forthemedium, and ≈40% for the tight working point. The jet with maximum discriminator value must pass the tight workingpoint of the al-gorithm, whilethe second isrequiredto pass thelooseone. The correctionfactors forb jetidentificationare appliedto simulated eventstoreproducethedatadistributionoftheb tagging discrim-inator.Ineventswithmorejetspassingtheselection criteria,the twowiththelargestpTaretaken.

The imbalance in the transverse momentum in signal events is not expected to be large, as the contribution from neutrinos from semileptonic decays in b jets is typically small. The miss-ing transverse momentum, pmiss

T is defined as the magnitude of

thenegative vector sumof thetransverse momenta ofall recon-structed particles. The jet energy calibration introduces correc-tions tothe pmiss_T measurement [45].Events arerequiredto have

pmiss_T <60 GeV.

Assumingthe b quark jetsandmuonsarethe decayproducts ofthe pseudoscalar a1, itis expected tohave mbb≈mμμ≈ma1 in signalevents.Moreover, thesystemofmuonsandb quarkjetsis expectedtohavean invariant massclosetomh.A χ2 variable is

introducedas χ2 bb+χh2,where χbb= (mbb−mμμ) σbb and χh= (m_μμbb−mh) σh . (2)

Here σbb and σh are, respectively, the mass resolutions of the

di-b-quarkjetsystemandtheHiggsbosoncandidate,derivedfrom simulation. The mass resolution ofthe di-b-quark jet system in-creases linearly with ma1. It is evaluated on an event-by-event basis,wheremμμ isassumedtobeequaltoma1.Thedecaywidth ofa1 isnegligible compared withthe experimental mass

resolu-tions in the analysis. The distribution of χ2 _{in the signal}

sam-ple withma1=40 GeV iscompared withthat in backgroundsin Fig.1.Events areselectedwith χ2_{<5.InFig. 2, χ}

bb and χhare

shownin2D histograms forbackgroundsandforthe signal with

ma1=40 GeV,wherethecontourof χ

2_{<5 isalsopresented.This}

selection has a signal efficiency up to 64% while rejecting more than 95% of backgrounds. The tails in the χbb and χh

distribu-tions, arising from the imperfect energy estimation of b jets as

Fig. 1. Thedistributionofχ2 _{insimulatedbackgroundprocessesand thesignal}

processwithma1=40 GeV.Thesamplesarenormalisedtounity.

well ascombinatorics ofthe di-b-jetsystem, are morepopulated inbackgroundprocesses.Thesearchforthenewparticlea1is

per-formedwithin20≤ma1≤62.5 GeV.Aslightlywiderrange,driven by the narrow width of a1 and the high resolution of mμμ, is

used fortheeventselection; thuseventswithmμμ valuesnotin [19.5,63.5]GeV arediscarded. This ensures the full signal selec-tionefficiencyandtheproperbackgroundmodellingatthe bound-aries.

Amethodthatfullyreliesondataisusedtoestimatethe back-ground, asdescribed inSection 5.Simulatedbackgroundsamples are however used to optimise the selection. Fig. 3 shows distri-butions, in data andsimulation, for events passing the selection requirementsexceptthoseofpmiss_T and χ2_{.Inthisfigure,expected}

numberofsimulatedeventsisnormalisedtotheintegrated lumi-nosityof35.9 fb−1.Dataandsimulationarecomparedforthe pT

ofthedimuonsystem,andthemassandpTofthedi-b-jetsystem.

Usingthesameselectedmuonandjetpairs,Fig.3alsoillustrates the distributions oftheinvariant mass mμμbb andthe transverse

momentum pμμ_T bb ofthe four-body system. The distributions for simulated eventsfollow reasonablythose inthe data, within the statistical uncertainties presentedin thefigure. The yieldin data andtheexpectedyieldsinsimulationarepresentedinTable1.The expectedyieldfromasignal ofh→a1a1→μ+μ−τ+τ− isfound

tobearound0.01withthemodelparametersusedinthistable. Toenhancethesensitivity,aneventcategorisationisemployed: different categorisation schemes are tried, and the one resulting inthehighestexpectedsignificanceischosen.Thedataina side-band regionareusedtodeterminethecategorisationthat ismost sensitive forthisanalysis. The sidebandregionis constructed us-ing the same selection as that for the signal region except that 5<χ2_{<11. In simulated background samples, the correlations}

between χ2 _and

mμμ andthevariablesusedforcategorisationare found to be small. The best sensitivityis found with categorisa-tion according to the b tagging discriminator value of the loose b-tagged jet. The tight-tight (TT) category contains events with both jets passing the tight requirements of the b jet identifica-tion algorithm.Eventsin whichthelooseb-taggedjet passesthe medium b tagging requirementsbutfailsthetightconditionsfall

Table 1

Eventyieldsforsimulatedprocessesanddataafterrequiringtwomuonsandtwob jets(μ+μ−bb selection)andafterthefinalselection.Theexpectednumberofsimulatedeventsisnormalisedto theintegratedluminosityof35.9 fb−1.Uncertaintiesarestatisticalonly.

Process μ+μ−bb selection Final selection

Top (tt, single top quark) 33 730±120 198±9

Drell–Yan 5237±77 399±21

Diboson 51±4 1±0.1

Total expected background 39 015±140 598±23

Data 36 360 610

Signal forσhB≈8 fb

ma1=20 GeV 14.0±0.1 6.0±0.1

ma1=40 GeV 14.8±0.1 7.5±0.1

ma1=60 GeV 16.7±0.1 10.1±0.1

Fig. 2. ThedistributionofχbbversusχhasdefinedinEq. (2) for(upper)simulated

backgroundprocessesand(lower)thesignalprocesswithma1=40 GeV.The con-toursencircletheareawithχ2_{<5.Thegreyscalerepresentstheexpectedyields}

at35.9 fb−1.

into thetight-medium(TM) category. The remaining eventswith thelooseb-taggedjetfailingthemediumrequirementsoftheb jet identificationalgorithmbelongtothetight-loose(TL)category.On average,41%ofsignaleventspasstheTLselection,while32%fulfil theTM requirementsand27%belong tothe TTcategory. Accord-ingtothedatainthesidebandregion,themajorityofbackground events (≈70%) fall into the TLcategory whereas about20% pass theTMrequirementsandlessthan10%canmeettheTTcriteria. 5. Signalandbackgroundmodelling

Thesearchisperformedusinganunbinnedfittothemμμ

dis-tributionindata,simultaneouslyintheTT,TM,andTLcategories. The signal shapeis modelledwitha weighted sumofVoigt pro-file [47] andCrystalBall(CB)functions [48],wherethemean val-uesofthetwoareboundtobethesame.Theinitialvaluesforthe signal modelparameters areextractedfroma simultaneousfit of themodeltothesimulatedsignalsamplesdescribedinSection3. Almost all parameters inthe signal model are found tobe inde-pendentofma1 andarefixed inthefinal fit.The onlyexceptions aretheresolutionparameteroftheVoigtprofileandCBfunctions, σvand σcb,respectively.Theseparametersdependlinearlyonma1 and onlytheir slopes, respectively α and β, float inthe final fit withintheiruncertainties,

σv=σv,0+αmμμ,

σcb=σcb,0+ βmμμ.

(3)

Theexpectedsignalefficiencyandacceptanceareinterpolatedfor

ma1 values not covered by simulation. The mμμ distribution in dataisusedtoevaluatethecontributionofbackgrounds.The un-certainty associated with the choice of the background model is treatedinasimilarwayasotheruncertaintiesforwhichthereare nuisance parameters in the fit.The unbinnedlikelihood function forthesignal-plus-backgroundfithastheform

L(data|s(p,mμμ)+b(mμμ)), (4)

wheres(p,mμμ)istheparametricsignalshapewiththesetof pa-rametersindicatedbyp,andb(mμμ)isthebackgroundmodel.The shapeforthebackgroundismodelled,independentlyineach cat-egory,witha setofanalyticfunctionsusingthediscrete profiling method [49–51].Inthisapproachthechoiceofthefunctionalform ofthebackground shapeisconsidered asadiscrete nuisance pa-rameter,forwhichthebestfitvalue canvaryasthetrialvalue of theparameterofinterest(mμμ)varies.Thebackgroundparameter spacetherefore contains multiplemodels,each including itsown parameters.

Fig. 3. ThedistributionofthepTofthe(topleft)dimuonand(topright)di-b-jetsystem,themassofthe(middleleft)di-b-jetand(middleright)μμbb system,and(bottom

left)thepToftheμμbb system,allafterrequiringtwomuonsandtwob-taggedjetsintheevent.Simulatedsamplesarenormalisedtoanintegratedluminosityof35.9 fb−1

Fig. 4. Thebestfitoutputtothedataunderthebackground-onlyhypothesisforthe(topleft)TLcategory,(topright)TMcategory,(bottomleft)TTcategoryand(bottom right)allcategories,presentedtogetherwith68%CL uncertaintybandforthebackgroundmodel.

Toprovidetheinputbackgroundmodelstothediscrete profil-ingmethod,thedataaremodelledwithdifferentparametrisations of polynomials. The degrees of the polynomials are determined through statistical tests(F-test) [52] to ensure the sufficiency of numberofparametersandtoavoidover-fittingthedata.Theinput backgroundfunctions are tried inthe minimisation of the nega-tivelogarithmofthelikelihood witha penaltytermaddedto ac-countforthenumberoffreeparametersinthebackgroundmodel. Thediscreteprofilingmethodcanchooseadifferentbest-fit func-tionalformforthebackgroundasthephysicsparameterofinterest varies,thuseffectivelyincorporatingthesystematicuncertaintyon thebackgroundfunctionalform:inthepresentanalysistheresult istoyieldexpectedupperlimitsthat areabout10%lessstringent than those obtained with a single functional form for the back-ground. The likelihoodratio forthe penalisedlikelihood function 

Lcanbewrittenas

−2 lnL(data|μ, ˆθμ, ˆbμ) 

L(data| ˆμ, ˆθ , ˆb) , (5)

where μisthemeasuredquantity.Thenumeratoristhemaximum penalisedlikelihoodforagiven μ,atthebestfitvaluesofnuisance parameters, ˆθμ andof thebackgroundfunction,bμ.ˆ The

denomi-natoristheglobalmaximumforL,achievedat μ = ˆμ,θ= ˆθand

b= ˆb.Aconfidenceintervalfor μisobtainedwiththebackground functionmaximisingLforanyvalueof μ[49].

6. Systematicuncertainties

Thestatisticalinterpretation oftheanalysistakesintoaccount severalsourcesofsystematicuncertaintiesrelatedtotheaccuracy inthesignalmodellinganduncertaintiesinthesignalacceptance. Theimpreciseknowledgeofthebackgroundcontributionsistaken into account by the discrete profiling method described in Sec-tion5.

Theoreticaluncertainties: toevaluatetheupperlimit onB(h→ a1a1→μ+μ−bb),theHiggsbosonproductioncrosssectionisset

totheSMpredictionwhereanuncertaintyof4.7%isconsideredfor thesumoftheggF andVBFproductioncrosssections,accounting forPDFand αsuncertainties [25].

Uncertaintiesinsignalshapeandacceptancemodelling: an uncer-taintyof2.5%isassignedtotheintegratedluminosityoftheCMS 13TeVdatacollectedin2016 [40].Theuncertaintyinthenumber of pileup interactions per event is estimated by varying the to-talinelasticppcrosssectionby ±4.6% [53].Thesimulation-to-data correction factors for the trigger efficiency, muon reconstruction, and selection efficiencies are estimated using a “tag-and-probe” method [54] inDrell–Yandata andsimulatedsamples.These un-certaintiesincludethepileupdependenceofthecorrectionfactors. For the jet energy scale (JES), the variations are made accord-ing to the η- and pT-dependent uncertainties andpropagated to

the pmiss

T oftheevent.Anadditionaluncertainty,arisingfrom

un-clusteredenergies in the event, is assessed for pmiss

T . Forthe jet

energyresolution,thesmearingcorrectionsarevariedwithintheir uncertainties [44]. Systematic uncertainty sources that affectthe simulation-to-datacorrectionsof theb tagging discriminator dis-tribution are JES, the contaminations from light flavor (LF) jets in the b-jet sample, the contaminations from heavy flavor (HF) jetsin the light-flavor jet sample, andthe statistical fluctuations indata andMC. The uncertainties dueto JES andlight-flavor jet contamination in b-jet samples are found to be dominant [46]. Uncertaintiesinthechoiceoftherenormalisation, μr,and

factori-sation, μf,scalesareestimatedbydoublingandhalving μrand μf

simultaneouslyinthesignalsample.Toestimatetheuncertainties associated with the parton showering and fragmentation model, additionalsignalsamplesare producedusing herwig ++ [55] and comparedto pythia.Finally,uncertainties arisingfromthelimited understandingofthePDFs [56] aretakenintoaccount.These un-certaintieshaveanegligibleeffectontheshapeofthesignal.Their effectsontheyieldaretakenintoaccountbyintroducingnuisance parameterswithlog-normaldistributionsintothefit.

7. Results

TheanalysisyieldsnosignificantexcessofeventsovertheSM background prediction.Fig. 4 showsthe mμμ distribution inthe dataofallcategoriestogetherwiththebestfitoutputforthe back-groundmodel,includinguncertainties.

The upperlimit on σhB(h→a1a1→μ+μ−bb) isobtained at

95%CL using theCLs criterion [57,58] andanasymptotic

approx-imation to the distribution of the profiled likelihood ratio test statistic [59].AssumingtheSMcrosssectionsfortheHiggsboson productionprocesseswithinthetheoreticaluncertainties,anupper limitisplacedonB(h→a1a1→μ+μ−bb)usingthesame

proce-dure.Limitsareevaluatedasafunctionofma1.Theobservedand expectedlimits are illustrated inFig. 5 forboth cases.Dominant systematicuncertaintiesare thoseassociatedwiththeb jet iden-tification, followed by the modellingof parton shower and frag-mentation. Forma1=40 GeV, the b tagging uncertainties arising fromLFcontaminationandJESamountto17and14%,respectively. Theuncertaintyarisingfromthepartonshowerandfragmentation modelsisabout7%.Otheruncertaintiesarebelow5%.

At 95% CL, the observed upper limits on B(h →a1a1 →

μ+μ−bb) are (1–7)×10−4 _{forthe mass range 20 to 62.5 GeV,}

whilsttheexpectedlimitsare(1–3)×10−4.Asimilarsearchfrom CMSinRunI [14] ledtoobservedupperlimitsof(2–8)×10−4 _at

95%CL,consideringtheggF Higgsbosonproductionandthemass range25≤ma1≤62.5 GeV.Thecorrespondingexpectedlimitson thebranchingfractionat95%CL are (3–4)×10−4_{.At13 TeV,the}

ggF Higgs bosonproductioncrosssection hasincreasedby a fac-tor of about 2.3 over that at 8 TeV, while the production cross sectionofmainbackgrounds,Drell–Yanandtt,hasincreasedbya factorof1.5and3.3, respectively.Despitetherelative increase in backgrounds,bettersensitivityisachievedusingimprovedanalysis techniquesinRunII.

Fig. 5. Observedandexpectedupperlimitsat95%CL onthe(upper)productofthe Higgsbosonproduction crosssection andB(h→a1a1→μ+μ−bb)and (lower)

thebranchingfractionasafunctionofma1.Theinnerandouterbandsindicatethe regionscontainingthedistributionoflimitslocatedwithin68and95%confidence intervals,respectively,oftheexpectationunderthebackground–onlyhypothesis.

Observed limits on B(h→a1a1) are shown in Fig. 6 in the

plane of(ma1,tanβ) fortype-III andtype-IV2HDM+S, usingonly the μ+μ−bb signal.The allowedrangesforB(h→a1a1)≤1 and

B(h→a1a1)≤0.34 [7] arealsopresented.

The effect of including the μ+μ−τ+τ− signal is studied in the (ma1,tanβ) plane forthefour typesof2HDM+S. Fora given

(ma1,tanβ) the relevance of μ+μ−τ+τ− depends on the ratio

B(a1→τ τ)μμτ τsel. /B(a1→bb)sel._μμbb aswell asthe sensitivityof

the analysis. Here sel. _{refers tothe acceptanceandthe selection}

efficiencyoftheprocess.Theratio sel.

μμτ τ/μμsel.bbisabout1%inthe

TLcategorywhileitreducesto0.3and0.1%intheTMandTT cat-egories, respectively. However,because oftheincrease inthe rel-ativebranching fraction,the contributionofthe μ+μ−τ+τ−

sig-Fig. 6. Observedupperlimitsat95%CL onB(h→a1a1)intheplaneof(ma1,tanβ) for(upper)type-IIIand(lower)type-IV2HDM+S,usingonlytheμ+μ−bb signal.

nalbecomes nonnegligibleinthetype-III2HDM+Swithtanβ≈5. Fig.7showstheobservedlimitsonB(h→a1a1)inthe(ma1,tanβ) plane,includingthecontributionof μ+μ−τ+τ−signalfortype-III 2HDM+S.Theobserved limitcontoursofB(h→a1a1)=1.00 and

B(h→a1a1)=0.34 aregenerallyextended comparedwithFig.6

(upper).

8. Summary

A search for the Higgs boson decay to a pair of new pseu-doscalarsh→a1a1→μ+μ−bb,motivatedbythenext-to-minimal

supersymmetric standard model and other extensions to two-Higgs-doublet models, is carried out using a sample of proton-proton collision data corresponding to an integrated luminosity of 35.9 fb−1 at 13 TeV centre-of-mass energy. No statistically significant excess is found in data with respect to the back-ground prediction. The results of the analysis are presented in theformofupperlimits, at95%confidencelevel,on theproduct ofthe Higgs boson production cross section andbranching frac-tion, σhB(h→a1a1→μ+μ−bb) as well as on the Higgs boson

branchingfractionassuming theSM predictionof σh.Theformer

Fig. 7. Observedupperlimitsat95%CL onB(h→a1a1)intheplaneof(ma1,tanβ) fortype-III2HDM+S,includingμ+μ−τ+τ−signalthatismisidentifiedasμ+μ−bb.

ranges between5 and33 fb, dependingon ma1.The correspond-ing upper limitson the branching fraction are (1–7)×10−4 _for

themassrangeof20≤ma1≤62.5 GeV. Inananalysisperformed by ATLAS [19], the upper limits on the branching fraction are (1.2–8.4)×10−4_{.ComparedwiththesimilaranalysisinRunI [14],}

theexpectedupperlimitsonthebranchingfractionareimproved byafactorbetween1.4and1.8for25≤ma1≤62.5 GeV.

Acknowledgements

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,wegratefullyacknowledgethecomputingcentresand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythe computinginfrastructureessential to ouranalyses. Finally, we acknowledge the enduring support for the construc-tionandoperation oftheLHC andtheCMSdetectorprovidedby thefollowing fundingagencies:BMBWF andFWF(Austria); FNRS and FWO(Belgium); CNPq,CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIENCIAS (Colombia); MSES andCSF (Croatia); RPF (Cyprus); SENESCYT(Ecuador);MoER,ERCIUT,andERDF(Estonia);Academy ofFinland,MEC,andHIP(Finland);CEAandCNRS/IN2P3(France); BMBF, DFG, and HGF (Germany); GSRT (Greece); NKFIA (Hun-gary);DAEandDST(India);IPM(Iran);SFI(Ireland);INFN(Italy); MSIPandNRF (RepublicofKorea); MES(Latvia);LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, andUASLP-FAI(Mexico);MOS(Montenegro);MBIE(NewZealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna);MON,ROSATOM,RAS,RFBR,andNRCKI(Russia);MESTD (Serbia);SEIDI,CPAN,PCTI,andFEDER(Spain);MoSTR (SriLanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TÜBITAK and TAEK (Turkey); NASU andSFFR (Ukraine); STFC(United Kingdom); DOEandNSF (USA).

Individuals have received support from the Marie-Curie pro-gramme and the European Research Council and Horizon 2020 Grant,contract No. 675440 (EuropeanUnion);the Leventis Foun-dation; the A.P. Sloan Foundation; the Alexander von Humboldt

Foundation; the Belgian Federal Science Policy Office; the Fonds pourlaFormationàlaRecherchedansl’Industrieetdans l’Agricul-ture(FRIA-Belgium); the Agentschapvoor Innovatie door Weten-schap en Technologie (IWT-Belgium); the F.R.S.-FNRS and FWO (Belgium)underthe“ExcellenceofScience–EOS”–be.hprojectn. 30820817;theMinistryofEducation,YouthandSports(MEYS)of theCzech Republic; theLendület (“Momentum”) Programme and the János Bolyai Research Scholarshipof theHungarian Academy ofSciences, the NewNationalExcellence ProgramÚNKP,the NK-FIAresearch grants123842,123959,124845,124850,and125105 (Hungary); the Council of Science and Industrial Research, In-dia; the HOMING PLUS programme of the Foundation for Pol-ish Science, cofinanced from European Union, Regional Develop-ment Fund, the MobilityPlus programmeof the Ministryof Sci-enceandHigher Education,the NationalScienceCenter (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/ 02543,2014/15/B/ST2/03998,and2015/19/B/ST2/02861,Sonata-bis 2012/07/E/ST2/01406;theNationalPrioritiesResearchProgramby Qatar National Research Fund; the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509 and the Programa Severo Ochoa delPrincipadodeAsturias;theThalisandAristeiaprogrammes co-financedbyEU-ESFandtheGreekNSRF;theRachadapisekSompot FundforPostdoctoralFellowship,ChulalongkornUniversityandthe ChulalongkornAcademicintoIts2ndCenturyProjectAdvancement Project(Thailand);theWelchFoundation,contractC-1845;andthe WestonHavensFoundation(USA).

References

[1] ATLASCollaboration,Observationofanewparticleinthesearchforthe stan-dardmodelHiggsbosonwiththeATLASdetectorattheLHC,Phys.Lett.B716 (2012)1,https://doi.org/10.1016/j.physletb.2012.08.020,arXiv:1207.7214. [2] CMSCollaboration,Observationofanewboson atamassof125 GeVwith

theCMSexperimentattheLHC,Phys.Lett.B716(2012)30,https://doi.org/10. 1016/j.physletb.2012.08.021,arXiv:1207.7235.

[3] CMSCollaboration,Observationofanewbosonwithmassnear125 GeVin pp collisionsat√s=7 and8 TeV,J.HighEnergyPhys.06(2013)081,https:// doi.org/10.1007/JHEP06(2013)081,arXiv:1303.4571.

[4] L.Evans,P.Bryant,LHCmachine,J.Instrum.3(2008)S08001,https://doi.org/ 10.1088/1748-0221/3/08/S08001.

[5] ATLASCollaboration,MeasurementoftheHiggsbosoncouplingpropertiesin the H→ZZ∗→4 decaychannelat√s=13 TeV withtheATLASdetector, J.HighEnergyPhys.03(2018)095,https://doi.org/10.1007/JHEP03(2018)095, arXiv:1712.02304.

[6] CMS Collaboration, Measurementsof properties ofthe Higgsboson decay-inginto thefour-leptonfinalstateinpp collisionsat√s=13 TeV,J. High Energy Phys. 11(2017)047,https://doi.org/10.1007/JHEP11(2017)047, arXiv: 1706.09936.

[7] ATLAS and CMSCollaborations, Measurements ofthe Higgs boson produc-tionanddecay ratesandconstraintsonitscouplingsfromacombined AT-LAS and CMSanalysisofthe LHCpp collision dataat √s=7 and8TeV, J.HighEnergyPhys.08(2016)045,https://doi.org/10.1007/JHEP08(2016)045, arXiv:1606.02266.

[8] CMSCollaboration,Studyofthemassandspin-parityoftheHiggsboson candi-dateviaitsdecaystoZ bosonpairs,Phys.Rev.Lett.110(2013)081803,https:// doi.org/10.1103/PhysRevLett.110.081803,arXiv:1212.6639.

[9] D.Curtin,R.Essig,S.Gori,P.Jaiswal,A.Katz,T.Liu,Z.Liu,D.McKeen,J.Shelton, M.Strassler,Z.Surujon,B.Tweedie,Y.-M.Zhong,Exoticdecaysofthe125 GeV Higgsboson,Phys.Rev.D90(2014)075004,https://doi.org/10.1103/PhysRevD. 90.075004,arXiv:1312.4992.

[10] CMS Collaboration, Combined measurements of Higgs boson couplings in proton-protoncollisionsat√s=13 TeV,Eur.Phys.J.C79(2019)421,https:// doi.org/10.1140/epjc/s10052-019-6909-y.

[11] ATLASCollaboration,SearchforHiggsbosonsdecayingtoaa intheμμτ τfinal stateinpp collisionsat √s=8 TeV withtheATLAS experiment,Phys.Rev. D92(2015)052002,https://doi.org/10.1103/PhysRevD.92.052002,arXiv:1505. 01609.

[12] CMSCollaboration,Asearchforpair productionofnewlightbosons decay-ingintomuons,Phys.Lett.B752(2016)146,https://doi.org/10.1016/j.physletb. 2015.10.067,arXiv:1506.00424.

[13] CMSCollaboration,SearchforaverylightNMSSMHiggsbosonproducedin decaysofthe125 GeVscalarbosonanddecayinginto τ leptonsinpp

col-lisionsat √s=8 TeV,J.HighEnergyPhys.01(2016)079,https://doi.org/10. 1007/JHEP01(2016)079,arXiv:1510.06534.

[14] CMS Collaboration,Searchforlight bosonsindecays ofthe 125 GeVHiggs bosoninproton-protoncollisionsat√s=8 TeV,J.HighEnergyPhys.10(2017) 076,https://doi.org/10.1007/JHEP10(2017)076,arXiv:1701.02032.

[15] ATLASCollaboration,SearchfortheHiggsbosonproducedinassociationwith aWbosonand decayingtofourb-quarksviatwospin-zero particlesinpp collisionsat13 TeVwiththeATLAS detector,Eur.Phys. J.C76(2016)605,

https://doi.org/10.1140/epjc/s10052-016-4418-9,arXiv:1606.08391.

[16] ATLASCollaboration,Searchfor Higgsbosondecaysto beyond-the-Standard-Model light bosons in four-lepton events with the ATLAS detector at

√

s=13 TeV, J. High Energy Phys. 06 (2018) 166, https://doi.org/10.1007/ JHEP06(2018)166,arXiv:1802.03388.

[17] ATLAS Collaboration, Search for Higgs boson decays into pairs of light (pseudo)scalarparticlesintheγ γjj finalstateinpp collisionsat√s=13 TeV withtheATLASdetector,Phys.Lett.B782(2018)750,https://doi.org/10.1016/ j.physletb.2018.06.011,arXiv:1803.11145.

[18] ATLASCollaboration,SearchfortheHiggsbosonproducedinassociationwith avectorbosonanddecayingintotwospin-zeroparticlesintheH→aa→4b channelin pp collisions at √s=13 TeV with the ATLAS detector, J. High EnergyPhys. 10(2018) 031,https://doi.org/10.1007/JHEP10(2018)031,arXiv: 1806.07355.

[19] ATLASCollaboration,SearchforHiggsbosondecaysintoapairoflightbosons inthebbμμfinalstateinpp collisionat√s=13 TeV withtheATLASdetector, Phys.Lett.B790(2019)1,https://doi.org/10.1016/j.physletb.2018.10.073,arXiv: 1807.00539.

[20] CMSCollaboration,SearchforanexoticdecayoftheHiggsbosontoapairof lightpseudoscalarsinthefinalstatewithtwobquarksandtwoτleptonsin proton-protoncollisionsat√s=13 TeV,Phys.Lett.B785(2018)462,https:// doi.org/10.1016/j.physletb.2018.08.057,arXiv:1805.10191.

[21] CMSCollaboration, SearchforanexoticdecayoftheHiggsbosontoapair oflightpseudoscalarsinthefinalstateoftwomuonsandtwoτ leptonsin proton-protoncollisionsat√s=13 TeV,J.HighEnergyPhys.11(2018)018,

https://doi.org/10.1007/JHEP11(2018)018,arXiv:1805.04865.

[22] M.Dine,W.Fischler,M.Srednicki,AsimplesolutiontothestrongCPproblem withaharmlessaxion,Phys.Lett.B104(1981)199,https://doi.org/10.1016/ 0370-2693(81)90590-6.

[23] J.E.Kim,H.P.Nilles,Theμ-problemandthestrongCP-problem,Phys.Lett.B 138(1984)150,https://doi.org/10.1016/0370-2693(84)91890-2.

[24] U. Ellwanger, C.Hugonie, A.M.Teixeira, Thenext-to-minimal supersymmet-ricstandardmodel,Phys.Rep.496(2010)1,https://doi.org/10.1016/j.physrep. 2010.07.001,arXiv:0910.1785.

[25] D. deFlorian,etal.,Handbook ofLHCHiggsCross Sections: 4.Deciphering theNatureoftheHiggsSector,CERNReportCERN-2017-002-M,2016,https:// doi.org/10.23731/CYRM-2017-002,arXiv:1610.07922.

[26] D.Curtin,R.Essig,Y.-M.Zhong,UncoveringlightscalarswithexoticHiggs de-caystobbμ+μ−,J.HighEnergyPhys.06(2015)025,https://doi.org/10.1007/ JHEP06(2015)025,arXiv:1412.4779.

[27] CMS Collaboration, Performance ofthe CMS muon detector and muon re-construction with proton-proton collisions at √s=13 TeV, J. Instrum. 13 (2018) P06015, https://doi.org/10.1088/1748-0221/13/06/P06015, arXiv:1804. 04528.

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

[29] J. Alwall,R. Frederix,S. Frixione, V.Hirschi, F.Maltoni, O. Mattelaer, H.-S. Shao, T. Stelzer, P. Torielli, M. Zaro, The automated computation of tree-levelandnext-to-leadingorderdifferentialcrosssections,andtheirmatching toparton showersimulations,J. HighEnergy Phys. 07(2014) 079,https:// doi.org/10.1007/JHEP07(2014)079,arXiv:1405.0301.

[30] Y. Li, F. Petriello,Combining QCD and electroweak corrections todilepton productioninfewz,Phys. Rev.D86(2012)094034,https://doi.org/10.1103/ PhysRevD.86.094034,arXiv:1208.5967.

[31] E.Re,Single-topWt-channelproductionmatchedwithpartonshowersusing thepowhegmethod,Eur.Phys.J.C71(2011)1547,https://doi.org/10.1140/ epjc/s10052-011-1547-z,arXiv:1009.2450.

[32] S. Alioli, P.Nason, C.Oleari, E.Re,A general framework for implementing NLOcalculationsinshowerMonteCarloprograms:thepowhegBOX,J.High EnergyPhys. 06(2010)043,https://doi.org/10.1007/JHEP06(2010)043, arXiv: 1002.2581.

[33] S.Alioli,P.Nason,C.Oleari,E.Re,NLOsingle-topproductionmatched with showerinPOWHEG:s- andt-channelcontributions,J.HighEnergyPhys.09 (2009)111, https://doi.org/10.1088/1126-6708/2009/09/111, arXiv:0907.4076, Erratum:https://doi.org/10.1007/JHEP02(2010)011.

[34] S.Frixione,P.Nason,C.Oleari,MatchingNLOQCDcomputationswithparton showersimulations:thepowhegmethod,J.HighEnergyPhys.11(2007)070,

https://doi.org/10.1088/1126-6708/2007/11/070,arXiv:0709.2092.

[35] R.D. Ball, et al., NNPDF, Parton distributions for the LHC Run II, J. High EnergyPhys. 04(2015)040,https://doi.org/10.1007/JHEP04(2015)040, arXiv: 1410.8849.

[36] T.Sjöstrand,S. Ask,J.R.Christiansen,R.Corke,N. Desai,P.Ilten, S.Mrenna, S.Prestel,C.O. Rasmussen,P.Z.Skands, Anintroductiontopythia 8.2, Com-put.Phys.Commun.191(2015)159,https://doi.org/10.1016/j.cpc.2015.01.024, arXiv:1410.3012.

[37] P.Skands,S.Carrazza,J.Rojo,Tuningpythia8.1:theMonash2013tune,Eur. Phys. J. C 74 (2014) 3024, https://doi.org/10.1140/epjc/s10052-014-3024-y, arXiv:1404.5630.

[38] CMSCollaboration,Eventgeneratortunesobtainedfromunderlyingeventand multipartonscatteringmeasurements,Eur.Phys.J.C76(2016)155,https:// doi.org/10.1140/epjc/s10052-016-3988-x,arXiv:1512.00815.

[39] S. Agostinelli, et al., GEANT4, Geant4—a simulation toolkit, Nucl. Instrum. MethodsPhys.Res.,Sect.A,Accel.Spectrom.Detect.Assoc.Equip.506(2003) 250,https://doi.org/10.1016/S0168-9002(03)01368-8.

[40] CMSCollaboration, CMSLuminosity Measurements for the 2016 Data Tak-ingPeriod,CMSPhysicsAnalysisSummaryCMS-PAS-LUM-17-001,2017,URL:

http://cds.cern.ch/record/2257069.

[41] M.Cacciari,G.P.Salam,G.Soyez,Theanti-kTjetclusteringalgorithm,J.High

Energy Phys.04(2008) 063,https://doi.org/10.1088/1126-6708/2008/04/063, arXiv:0802.1189.

[42] M.Cacciari,G.P.Salam,G.Soyez,FastJetusermanual,Eur.Phys.J.C72(2012) 1896,https://doi.org/10.1140/epjc/s10052-012-1896-2,arXiv:1111.6097. [43] CMSCollaboration,Particle-flow reconstructionandglobalevent description

withtheCMSdetector,J.Instrum.12(2017)P10003,https://doi.org/10.1088/ 1748-0221/12/10/P10003,arXiv:1706.04965.

[44] CMSCollaboration,Jet AlgorithmsPerformancein13TeVData,CMSPhysics AnalysisSummaryCMS-PAS-JME-16-003,2017,URL:http://cds.cern.ch/record/ 2256875.

[45] CMSCollaboration,Determinationofjetenergycalibrationandtransverse mo-mentumresolutioninCMS, J.Instrum. 6(2011) P11002,https://doi.org/10. 1088/1748-0221/6/11/P11002,arXiv:1107.4277.

[46] CMSCollaboration,Identificationofheavy-flavourjetswiththeCMSdetectorin pp collisionsat13 TeV,J.Instrum.13(2018)P05011,https://doi.org/10.1088/ 1748-0221/13/05/P05011,arXiv:1712.07158.

[47]G.Pagnini,R.K.Saxena,AnoteontheVoigtprofilefunction,arXiv:0805.2274, 2008.

[48] M.J.Oreglia,AStudyoftheReactionsψ→γ γψ,Ph.D.thesis,Stanford Univer-sity, 1980, URL: http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-r-236.pdf, SLACReportSLAC-R-236.

[49] P.D.Dauncey,M.Kenzie,N.Wardle,G.J.Davies,Handlinguncertaintiesin back-groundshapes:thediscreteprofilingmethod,J.Instrum. 10(2015)P04015,

https://doi.org/10.1088/1748-0221/10/04/P04015,arXiv:1408.6865.

[50] CMSCollaboration,ObservationofthediphotondecayoftheHiggsbosonand measurementofitsproperties,Eur.Phys.J.C74(2014)3076,https://doi.org/ 10.1140/epjc/s10052-014-3076-z,arXiv:1407.0558.

[51] ATLASandCMSCollaborations, Combinedmeasurementofthe Higgsboson massinpp collisionsat√s=7 and8 TeVwiththeATLASandCMS experi-ments,Phys.Rev.Lett.114(2015)191803,https://doi.org/10.1103/PhysRevLett. 114.191803,arXiv:1503.07589.

[52]F.James,StatisticalMethodsinExperimentalPhysics,seconded.,World Scien-tific,Singapore,2007.

[53] CMSCollaboration,Measurementoftheinelasticproton-protoncrosssection at √s=13 TeV,J.HighEnergy Phys.07(2018)161,https://doi.org/10.1007/ JHEP07(2018)161,arXiv:1802.02613.

[54] CMSCollaboration,MeasurementsofinclusiveW andZ crosssectionsinpp collisionsat√s=7 TeV,J.HighEnergyPhys.01(2011)080,https://doi.org/10. 1007/JHEP01(2011)080,arXiv:1012.2466.

[55] M.Bähr,S.Gieseke,M.A.Gigg,D.Grellscheid,K.Hamilton,O.Latunde-Dada, S. Plätzer,P.Richardson,M.H.Seymour,A.Sherstnev,B.R.Webber,herwig++ physicsandmanual,Eur.Phys.J.C58(2008)639,https://doi.org/10.1140/epjc/ s10052-008-0798-9,arXiv:0803.0883.

[56] J.Butterworth, etal., PDF4LHCrecommendationsfor LHCRun II, J.Phys. G 43(2016)023001,https://doi.org/10.1088/0954-3899/43/2/023001,arXiv:1510. 03865.

[57] T.Junk,Confidencelevelcomputationforcombiningsearcheswithsmall statis-tics, Nucl.Instrum.MethodsPhys.Res., Sect.A,Accel.Spectrom.Detect. As-soc. Equip. 434(1999) 435,https://doi.org/10.1016/S0168-9002(99)00498-2, arXiv:hep-ex/9902006.

[58] A.L.Read,Presentationofsearchresults:theCLstechnique,J.Phys.G28(2002)

2693,https://doi.org/10.1088/0954-3899/28/10/313.

[59] G.Cowan,K.Cranmer,E.Gross,O.Vitells,Asymptoticformulaefor likelihood-basedtestsofnewphysics,Eur.Phys.J.C71(2011)1554,https://doi.org/10. 1140/epjc/s10052-011-1554-0, arXiv:1007.1727, Erratum: https://doi.org/10. 1140/epjc/s10052-013-2501-z.

TheCMSCollaboration

A.M. Sirunyan,A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam, F. Ambrogi, E. Asilar,T. Bergauer, J. Brandstetter, M. Dragicevic, J. Erö,A. Escalante Del Valle,

M. Flechl,R. Frühwirth1,V.M. Ghete, J. Hrubec, M. Jeitler1,N. Krammer, I. Krätschmer,D. Liko,

T. Madlener,I. Mikulec, N. Rad, H. Rohringer, J. Schieck1, R. Schöfbeck, M. Spanring, D. Spitzbart,

W. Waltenberger, J. Wittmann, C.-E. Wulz1,M. Zarucki

InstitutfürHochenergiephysik,Wien,Austria

V. Chekhovsky, V. Mossolov,J. Suarez Gonzalez

InstituteforNuclearProblems,Minsk,Belarus

E.A. De Wolf,D. Di Croce, X. Janssen,J. Lauwers, A. Lelek, M. Pieters,H. Van Haevermaet,

P. Van Mechelen,N. Van Remortel

UniversiteitAntwerpen,Antwerpen,Belgium

S. Abu Zeid,F. Blekman, J. D’Hondt, J. De Clercq, K. Deroover, G. Flouris, D. Lontkovskyi,S. Lowette,

I. Marchesini,S. Moortgat, L. Moreels, Q. Python, K. Skovpen, S. Tavernier,W. Van Doninck,

P. Van Mulders,I. Van Parijs

VrijeUniversiteitBrussel,Brussel,Belgium

D. Beghin,B. Bilin, H. Brun, B. Clerbaux, G. De Lentdecker,H. Delannoy, B. Dorney, G. Fasanella,L. Favart,

D. Vannerom,Q. Wang UniversitéLibredeBruxelles,Bruxelles,Belgium

T. Cornelis,D. Dobur, A. Fagot,M. Gul, I. Khvastunov2, D. Poyraz, C. Roskas, D. Trocino,M. Tytgat,

W. Verbeke,B. Vermassen, M. Vit, N. Zaganidis

GhentUniversity,Ghent,Belgium

H. Bakhshiansohi,O. Bondu, G. Bruno,C. Caputo, P. David,C. Delaere, M. Delcourt, A. Giammanco,

G. Krintiras,V. Lemaitre, A. Magitteri, K. Piotrzkowski, A. Saggio, M. Vidal Marono, P. Vischia, J. Zobec

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

F.L. Alves,G.A. Alves, G. Correia Silva,C. Hensel, A. Moraes,M.E. Pol, P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas, W. Carvalho,J. Chinellato3,E. Coelho, E.M. Da Costa, G.G. Da Silveira4,

D. De Jesus Damiao,C. De Oliveira Martins, S. Fonseca De Souza, H. Malbouisson,D. Matos Figueiredo,

M. Melo De Almeida,C. Mora Herrera, L. Mundim,H. Nogima, W.L. Prado Da Silva, L.J. Sanchez Rosas,

A. Santoro, A. Sznajder,M. Thiel, E.J. Tonelli Manganote3,F. Torres Da Silva De Araujo, A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahujaa, C.A. Bernardesa, L. Calligarisa, T.R. Fernandez Perez Tomeia,E.M. Gregoresb,

P.G. Mercadanteb,S.F. Novaesa,Sandra S. Padulaa

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

A. Aleksandrov, R. Hadjiiska, P. Iaydjiev,A. Marinov, M. Misheva, M. Rodozov, M. Shopova,G. Sultanov

InstituteforNuclearResearchandNuclearEnergy,BulgarianAcademyofSciences,Sofia,Bulgaria

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

UniversityofSofia,Sofia,Bulgaria

W. Fang5, X. Gao5,L. Yuan

BeihangUniversity,Beijing,China

M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen,M. Chen, Y. Chen, C.H. Jiang, D. Leggat, H. Liao,Z. Liu,

S.M. Shaheen6,A. Spiezia, J. Tao, E. Yazgan, H. Zhang,S. Zhang6,J. Zhao

InstituteofHighEnergyPhysics,Beijing,China

Y. Ban, G. Chen, A. Levin, J. Li,L. Li, Q. Li, Y. Mao,S.J. Qian, D. Wang

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China Y. Wang

TsinghuaUniversity,Beijing,China

C. Avila,A. Cabrera, C.A. Carrillo Montoya, L.F. Chaparro Sierra, C. Florez, C.F. González Hernández,

M.A. Segura Delgado UniversidaddeLosAndes,Bogota,Colombia

B. Courbon, N. Godinovic, D. Lelas,I. Puljak, T. Sculac

Z. Antunovic,M. Kovac UniversityofSplit,FacultyofScience,Split,Croatia

V. Brigljevic,D. Ferencek, K. Kadija,B. Mesic, M. Roguljic, A. Starodumov7, T. Susa

InstituteRudjerBoskovic,Zagreb,Croatia

M.W. Ather,A. Attikis, M. Kolosova, G. Mavromanolakis,J. Mousa, C. Nicolaou, F. Ptochos,P.A. Razis,

H. Rykaczewski UniversityofCyprus,Nicosia,Cyprus

M. Finger8,M. Finger Jr.8

CharlesUniversity,Prague,CzechRepublic E. Ayala

EscuelaPolitecnicaNacional,Quito,Ecuador E. Carrera Jarrin

UniversidadSanFranciscodeQuito,Quito,Ecuador

A.A. Abdelalim9,10,S. Elgammal11, S. Khalil10

AcademyofScientificResearchandTechnologyoftheArabRepublicofEgypt,EgyptianNetworkofHighEnergyPhysics,Cairo,Egypt

S. Bhowmik, A. Carvalho Antunes De Oliveira,R.K. Dewanjee, K. Ehataht,M. Kadastik, M. Raidal,

C. Veelken

NationalInstituteofChemicalPhysicsandBiophysics,Tallinn,Estonia

P. Eerola,H. Kirschenmann, J. Pekkanen,M. Voutilainen

DepartmentofPhysics,UniversityofHelsinki,Helsinki,Finland

J. Havukainen, J.K. Heikkilä, T. Järvinen,V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini,S. Laurila,

S. Lehti,T. Lindén, P. Luukka, T. Mäenpää,H. Siikonen, E. Tuominen, J. Tuominiemi

HelsinkiInstituteofPhysics,Helsinki,Finland T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon,F. Couderc, M. Dejardin, D. Denegri,J.L. Faure, F. Ferri, S. Ganjour, A. Givernaud, P. Gras,

G. Hamel de Monchenault,P. Jarry, C. Leloup,E. Locci, J. Malcles,G. Negro, J. Rander, A. Rosowsky,

M.Ö. Sahin,M. Titov

IRFU,CEA,UniversitéParis-Saclay,Gif-sur-Yvette,France

A. Abdulsalam12,C. Amendola, I. Antropov, F. Beaudette, P. Busson, C. Charlot, R. Granier de Cassagnac,

I. Kucher, A. Lobanov, J. Martin Blanco, C. Martin Perez,M. Nguyen, C. Ochando, G. Ortona, P. Paganini,

J. Rembser,R. Salerno,J.B. Sauvan, Y. Sirois,A.G. Stahl Leiton, A. Zabi, A. Zghiche

LaboratoireLeprince-Ringuet,Ecolepolytechnique,CNRS/IN2P3,UniversitéParis-Saclay,Palaiseau,France

J.-L. Agram13,J. Andrea, D. Bloch,G. Bourgatte, J.-M. Brom, E.C. Chabert,V. Cherepanov, C. Collard,

E. Conte13,J.-C. Fontaine13, D. Gelé, U. Goerlach,M. Jansová, A.-C. Le Bihan, N. Tonon, P. Van Hove

S. Gadrat

CentredeCalculdel’InstitutNationaldePhysiqueNucleaireetdePhysiquedesParticules,CNRS/IN2P3,Villeurbanne,France

S. Beauceron,C. Bernet, G. Boudoul, N. Chanon, R. Chierici,D. Contardo, P. Depasse, H. El Mamouni,

J. Fay, L. Finco, S. Gascon,M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh, H. Lattaud,

M. Lethuillier, L. Mirabito,S. Perries, A. Popov14,V. Sordini, G. Touquet, M. Vander Donckt, S. Viret

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

A. Khvedelidze8

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze8

TbilisiStateUniversity,Tbilisi,Georgia

C. Autermann, L. Feld, M.K. Kiesel, K. Klein, M. Lipinski, M. Preuten,M.P. Rauch, C. Schomakers,J. Schulz,

M. Teroerde,B. Wittmer

RWTHAachenUniversity,I.PhysikalischesInstitut,Aachen,Germany

A. Albert, M. Erdmann,S. Erdweg, T. Esch,R. Fischer, S. Ghosh,T. Hebbeker, C. Heidemann, K. Hoepfner,

H. Keller, L. Mastrolorenzo, M. Merschmeyer,A. Meyer, P. Millet,S. Mukherjee, T. Pook,A. Pozdnyakov,

M. Radziej, H. Reithler,M. Rieger, A. Schmidt, D. Teyssier,S. Thüer

RWTHAachenUniversity,III.PhysikalischesInstitutA,Aachen,Germany

G. Flügge, O. Hlushchenko,T. Kress, T. Müller, A. Nehrkorn, A. Nowack,C. Pistone, O. Pooth,D. Roy,

H. Sert, A. Stahl15

RWTHAachenUniversity,III.PhysikalischesInstitutB,Aachen,Germany

M. Aldaya Martin,T. Arndt, C. Asawatangtrakuldee, I. Babounikau, K. Beernaert,O. Behnke, U. Behrens,

A. Bermúdez Martínez, D. Bertsche, A.A. Bin Anuar, K. Borras16,V. Botta, A. Campbell, P. Connor,

C. Contreras-Campana, V. Danilov,A. De Wit, M.M. Defranchis, C. Diez Pardos,D. Domínguez Damiani,

G. Eckerlin, T. Eichhorn, A. Elwood, E. Eren, E. Gallo17,A. Geiser, J.M. Grados Luyando, A. Grohsjean,

M. Guthoff,M. Haranko, A. Harb,H. Jung, M. Kasemann,J. Keaveney, C. Kleinwort, J. Knolle,D. Krücker,

W. Lange, T. Lenz,J. Leonard, K. Lipka,W. Lohmann18, R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer,

M. Meyer, M. Missiroli, G. Mittag, J. Mnich, V. Myronenko,S.K. Pflitsch, D. Pitzl,A. Raspereza, A. Saibel,

M. Savitskyi,P. Saxena, P. Schütze,C. Schwanenberger, R. Shevchenko, A. Singh, H. Tholen,O. Turkot,

A. Vagnerini,M. Van De Klundert, G.P. Van Onsem,R. Walsh, Y. Wen, K. Wichmann,C. Wissing,

O. Zenaiev

DeutschesElektronen-Synchrotron,Hamburg,Germany

R. Aggleton,S. Bein, L. Benato, A. Benecke, T. Dreyer, A. Ebrahimi, E. Garutti, D. Gonzalez, P. Gunnellini,

J. Haller, A. Hinzmann, A. Karavdina, G. Kasieczka, R. Klanner, R. Kogler, N. Kovalchuk,S. Kurz,

V. Kutzner, J. Lange,D. Marconi, J. Multhaup,M. Niedziela, C.E.N. Niemeyer,D. Nowatschin, A. Perieanu,

A. Reimers, O. Rieger,C. Scharf, P. Schleper, S. Schumann, J. Schwandt, J. Sonneveld,H. Stadie,

G. Steinbrück, F.M. Stober,M. Stöver, B. Vormwald, I. Zoi

UniversityofHamburg,Hamburg,Germany

M. Akbiyik, C. Barth,M. Baselga, S. Baur, E. Butz,R. Caspart, T. Chwalek, F. Colombo, W. De Boer,

A. Dierlamm, K. El Morabit,N. Faltermann, B. Freund,M. Giffels, M.A. Harrendorf,F. Hartmann15,

M. Plagge,G. Quast, K. Rabbertz, M. Schröder, I. Shvetsov,H.J. Simonis, R. Ulrich, S. Wayand,M. Weber,

T. Weiler, C. Wöhrmann, R. Wolf

KarlsruherInstitutfuerTechnologie,Karlsruhe,Germany

G. Anagnostou,G. Daskalakis, T. Geralis,A. Kyriakis, D. Loukas,G. Paspalaki

InstituteofNuclearandParticlePhysics(INPP),NCSRDemokritos,AghiaParaskevi,Greece

A. Agapitos,G. Karathanasis, P. Kontaxakis,A. Panagiotou, I. Papavergou, N. Saoulidou, K. Vellidis

NationalandKapodistrianUniversityofAthens,Athens,Greece

K. Kousouris,I. Papakrivopoulos,G. Tsipolitis

NationalTechnicalUniversityofAthens,Athens,Greece

I. Evangelou,C. Foudas, P. Gianneios, P. Katsoulis, P. Kokkas, S. Mallios,N. Manthos, I. Papadopoulos,

E. Paradas, J. Strologas,F.A. Triantis, D. Tsitsonis

UniversityofIoánnina,Ioánnina,Greece

M. Bartók19,M. Csanad, N. Filipovic, P. Major, M.I. Nagy, G. Pasztor, O. Surányi, G.I. Veres

MTA-ELTELendületCMSParticleandNuclearPhysicsGroup,EötvösLorándUniversity,Budapest,Hungary

G. Bencze,C. Hajdu, D. Horvath20, Á. Hunyadi, F. Sikler,T.Á. Vámi, V. Veszpremi, G. Vesztergombi†

WignerResearchCentreforPhysics,Budapest,Hungary

N. Beni,S. Czellar, J. Karancsi19,A. Makovec,J. Molnar, Z. Szillasi

InstituteofNuclearResearchATOMKI,Debrecen,Hungary

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

InstituteofPhysics,UniversityofDebrecen,Debrecen,Hungary

S. Choudhury,J.R. Komaragiri, P.C. Tiwari

IndianInstituteofScience(IISc),Bangalore,India

S. Bahinipati21,C. Kar, P. Mal, K. Mandal, A. Nayak22,S. Roy Chowdhury, D.K. Sahoo21,S.K. Swain

NationalInstituteofScienceEducationandResearch,HBNI,Bhubaneswar,India

S. Bansal,S.B. Beri, V. Bhatnagar, S. Chauhan,R. Chawla, N. Dhingra, R. Gupta, A. Kaur, M. Kaur, S. Kaur,

P. Kumari,M. Lohan, M. Meena, A. Mehta, K. Sandeep, S. Sharma, J.B. Singh, A.K. Virdi,G. Walia

PanjabUniversity,Chandigarh,India

A. Bhardwaj,B.C. Choudhary, R.B. Garg,M. Gola, S. Keshri, Ashok Kumar,S. Malhotra, M. Naimuddin,

P. Priyanka,K. Ranjan, Aashaq Shah, R. Sharma

UniversityofDelhi,Delhi,India

R. Bhardwaj23, M. Bharti23, R. Bhattacharya,S. Bhattacharya, U. Bhawandeep23, D. Bhowmik, S. Dey,

S. Dutt23,S. Dutta, S. Ghosh, M. Maity24, K. Mondal, S. Nandan,A. Purohit, P.K. Rout, A. Roy, G. Saha,

S. Sarkar,T. Sarkar24, M. Sharan, B. Singh23, S. Thakur23

SahaInstituteofNuclearPhysics,HBNI,Kolkata,India

P.K. Behera,A. Muhammad

R. Chudasama, D. Dutta, V. Jha, V. Kumar, D.K. Mishra,P.K. Netrakanti, L.M. Pant, P. Shukla, P. Suggisetti BhabhaAtomicResearchCentre,Mumbai,India

T. Aziz, M.A. Bhat,S. Dugad,G.B. Mohanty, N. Sur, Ravindra Kumar Verma

TataInstituteofFundamentalResearch-A,Mumbai,India

S. Banerjee, S. Bhattacharya, S. Chatterjee,P. Das, M. Guchait, Sa. Jain, S. Karmakar,S. Kumar,

G. Majumder, K. Mazumdar,N. Sahoo

TataInstituteofFundamentalResearch-B,Mumbai,India

S. Chauhan,S. Dube, V. Hegde, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, A. Rastogi, S. Sharma

IndianInstituteofScienceEducationandResearch(IISER),Pune,India

S. Chenarani25, E. Eskandari Tadavani,S.M. Etesami25,M. Khakzad, M. Mohammadi Najafabadi,

M. Naseri, F. Rezaei Hosseinabadi, B. Safarzadeh26,M. Zeinali

InstituteforResearchinFundamentalSciences(IPM),Tehran,Iran

M. Felcini,M. Grunewald

UniversityCollegeDublin,Dublin,Ireland

M. Abbresciaa,b, C. Calabriaa,b,A. Colaleoa,D. Creanzaa,c, L. Cristellaa,b,N. De Filippisa,c,

M. De Palmaa,b, A. Di Florioa,b, F. Erricoa,b,L. Fiorea, A. Gelmia,b,G. Iasellia,c,M. Incea,b, S. Lezkia,b, G. Maggia,c,M. Maggia, G. Minielloa,b, S. Mya,b, S. Nuzzoa,b, A. Pompilia,b,G. Pugliesea,c, R. Radognaa, A. Ranieria, G. Selvaggia,b,A. Sharmaa, L. Silvestrisa, R. Vendittia, P. Verwilligena

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

G. Abbiendia,C. Battilanaa,b,D. Bonacorsia,b,L. Borgonovia,b,S. Braibant-Giacomellia,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,E. Fontanesi, P. Giacomellia, C. Grandia,

L. Guiduccia,b,F. Iemmia,b,S. Lo Meoa,27,S. Marcellinia,G. Masettia,A. Montanaria,F.L. Navarriaa,b, A. Perrottaa,F. Primaveraa,b,A.M. Rossia,b,T. Rovellia,b,G.P. Sirolia,b, N. Tosia

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

S. Albergoa,b,A. Di Mattiaa,R. Potenzaa,b, A. Tricomia,b,C. Tuvea,b

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

G. Barbaglia, K. Chatterjeea,b,V. Ciullia,b,C. Civininia, R. D’Alessandroa,b, E. Focardia,b,G. Latino, P. Lenzia,b,M. Meschinia,S. Paolettia, L. Russoa,28, G. Sguazzonia, D. Stroma, L. Viliania

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

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

INFNLaboratoriNazionalidiFrascati,Frascati,Italy

F. Ferroa, R. Mulargiaa,b,E. Robuttia, S. Tosia,b

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

A. Benagliaa,A. Beschib,F. Brivioa,b,V. Cirioloa,b,15, S. Di Guidaa,b,15, M.E. Dinardoa,b,S. Fiorendia,b,

S. Gennaia,A. Ghezzia,b,P. Govonia,b,M. Malbertia,b,S. Malvezzia,D. Menascea,F. Monti, L. Moronia,

M. Paganonia,b,D. Pedrinia, S. Ragazzia,b, T. Tabarelli de Fatisa,b, D. Zuoloa,b

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

S. Buontempoa, N. Cavalloa,c,A. De Iorioa,b,A. Di Crescenzoa,b, F. Fabozzia,c,F. Fiengaa,G. Galatia, A.O.M. Iorioa,b,L. Listaa, S. Meolaa,d,15, P. Paoluccia,15, C. Sciaccaa,b, E. Voevodinaa,b

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

P. Azzia, N. Bacchettaa, D. Biselloa,b, A. Bolettia,b, A. Bragagnolo,R. Carlina,b,P. Checchiaa, M. Dall’Ossoa,b, P. De Castro Manzanoa,T. Dorigoa,U. Dossellia, F. Gasparinia,b, U. Gasparinia,b,

A. Gozzelinoa, S.Y. Hoh, S. Lacapraraa,P. Lujan, M. Margonia,b, A.T. Meneguzzoa,b,J. Pazzinia,b,

M. Presillab,P. Ronchesea,b,R. Rossina,b,F. Simonettoa,b, A. Tiko, E. Torassaa,M. Tosia,b, M. Zanettia,b, P. Zottoa,b_{, G. Zumerle}a,b

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

A. Braghieria, A. Magnania,P. Montagnaa,b, S.P. Rattia,b,V. Rea,M. Ressegottia,b,C. Riccardia,b, P. Salvinia, I. Vaia,b,P. Vituloa,b

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

M. Biasinia,b,G.M. Bileia,C. Cecchia,b,D. Ciangottinia,b, L. Fanòa,b,P. Laricciaa,b,R. Leonardia,b, E. Manonia,G. Mantovania,b,V. Mariania,b,M. Menichellia, A. Rossia,b,A. Santocchiaa,b, D. Spigaa

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

K. Androsova, P. Azzurria, G. Bagliesia, L. Bianchinia, T. Boccalia, L. Borrello, R. Castaldia,M.A. Cioccia,b, R. Dell’Orsoa,G. Fedia, F. Fioria,c, L. Gianninia,c, A. Giassia, M.T. Grippoa,F. Ligabuea,c, E. Mancaa,c, G. Mandorlia,c, A. Messineoa,b, F. Pallaa,A. Rizzia,b,G. Rolandi29,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. Cavallari}a_{,M. Cipriani}a,b_{, D. Del Re}a,b_{, E. Di Marco}a,b_{,M. Diemoz}a_{,S. Gelli}a,b_,

E. Longoa,b, B. Marzocchia,b,P. Meridiania, G. Organtinia,b,F. Pandolfia, R. Paramattia,b, F. Preiatoa,b, S. Rahatloua,b,C. Rovellia, F. Santanastasioa,b

a_{INFNSezionediRoma,Rome,Italy} b_{SapienzaUniversitàdiRoma,Rome,Italy}

N. Amapanea,b,R. Arcidiaconoa,c, S. Argiroa,b, M. Arneodoa,c,N. Bartosika,R. Bellana,b,C. Biinoa, A. Cappatia,b,N. Cartigliaa, F. Cennaa,b, S. Comettia, M. Costaa,b,R. Covarellia,b, N. Demariaa, B. Kiania,b,C. Mariottia, S. Masellia, E. Migliorea,b,V. Monacoa,b,E. Monteila,b,M. Montenoa, M.M. Obertinoa,b, L. Pachera,b, N. Pastronea,M. Pelliccionia, G.L. Pinna Angionia,b,A. Romeroa,b, M. Ruspaa,c,R. Sacchia,b,R. Salvaticoa,b, K. Shchelinaa,b,V. Solaa, A. Solanoa,b, D. Soldia,b,A. Staianoa

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

S. Belfortea,V. Candelisea,b,M. Casarsaa, F. Cossuttia,A. Da Rolda,b,G. Della Riccaa,b, F. Vazzolera,b,

A. Zanettia

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

D.H. Kim,G.N. Kim, M.S. Kim,J. Lee, S. Lee,S.W. Lee, C.S. Moon, Y.D. Oh, S.I. Pak, S. Sekmen,D.C. Son,

Y.C. Yang

KyungpookNationalUniversity,Daegu,RepublicofKorea

H. Kim,D.H. Moon, G. Oh

ChonnamNationalUniversity,InstituteforUniverseandElementaryParticles,Kwangju,RepublicofKorea

B. Francois, J. Goh30, T.J. Kim

HanyangUniversity,Seoul,RepublicofKorea

S. Cho,S. Choi, Y. Go, D. Gyun,S. Ha, B. Hong,Y. Jo, K. Lee,K.S. Lee, S. Lee, J. Lim, S.K. Park, Y. Roh

KoreaUniversity,Seoul,RepublicofKorea H.S. Kim

SejongUniversity,Seoul,RepublicofKorea

J. Almond, J. Kim,J.S. Kim, H. Lee,K. Lee, K. Nam,S.B. Oh, B.C. Radburn-Smith, S.h. Seo, U.K. Yang,

H.D. Yoo,G.B. Yu

SeoulNationalUniversity,Seoul,RepublicofKorea

D. Jeon, H. Kim,J.H. Kim, J.S.H. Lee, I.C. Park

UniversityofSeoul,Seoul,RepublicofKorea

Y. Choi,C. Hwang, J. Lee, I. Yu

SungkyunkwanUniversity,Suwon,RepublicofKorea

V. Veckalns31

RigaTechnicalUniversity,Riga,Latvia

V. Dudenas, A. Juodagalvis,J. Vaitkus

VilniusUniversity,Vilnius,Lithuania

Z.A. Ibrahim, M.A.B. Md Ali32, F. Mohamad Idris33, W.A.T. Wan Abdullah,M.N. Yusli, Z. Zolkapli

NationalCentreforParticlePhysics,UniversitiMalaya,KualaLumpur,Malaysia

J.F. Benitez, A. Castaneda Hernandez,J.A. Murillo Quijada

UniversidaddeSonora(UNISON),Hermosillo,Mexico

H. Castilla-Valdez, E. De La Cruz-Burelo,M.C. Duran-Osuna, I. Heredia-De La Cruz34,R. Lopez-Fernandez,

J. Mejia Guisao,R.I. Rabadan-Trejo, M. Ramirez-Garcia,G. Ramirez-Sanchez, R. Reyes-Almanza,

A. Sanchez-Hernandez

CentrodeInvestigacionydeEstudiosAvanzadosdelIPN,MexicoCity,Mexico

S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia