Measurement of the CP-violating weak phase phi(s) and the decay width difference Delta Gamma(s) using the B-s(0) -> J/psi phi (1020) decay channel in pp collisions at root s=8 TeV

UNIVERSIDADE ESTADUAL DE CAMPINAS

SISTEMA DE BIBLIOTECAS DA UNICAMP

REPOSITÓRIO DA PRODUÇÃO CIENTIFICA E INTELECTUAL DA UNICAMP

Versão do arquivo anexado / Version of attached file:

Versão do Editor / Published Version

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

https://www.sciencedirect.com/science/article/pii/S037026931630017X

DOI: 10.1016/j.physletb.2016.03.046

Direitos autorais / Publisher's copyright statement:

©2016 by Elsevier. All rights reserved.

DIRETORIA DE TRATAMENTO DA INFORMAÇÃO

Cidade Universitária Zeferino Vaz Barão Geraldo

CEP 13083-970 – Campinas SP

Fone: (19) 3521-6493

http://www.repositorio.unicamp.br

Contents lists available atScienceDirect

Physics

Letters

B

www.elsevier.com/locate/physletb

Measurement

of

the

CP-violating

weak

phase

φ

_s

and

the

decay

width

difference



_s

using

the

B

0

_s

→

J

/ψ φ (

1020

)

decay

channel

in

pp

collisions

at

√

s

=

8 TeV

.

CMS

Collaboration



CERN,Switzerland

a

r

t

i

c

l

e

i

n

f

o

a

b

s

t

r

a

c

t

Articlehistory: Received27July2015

Receivedinrevisedform11March2016 Accepted16March2016

Availableonline23March2016 Editor:M.Doser Keywords: CMS Physics B-physics CPviolation

The CP-violating weak phase φs of the B0s meson and the decay width difference s of the B0s

lightand heavy masseigenstates are measuredwith theCMS detectoratthe LHCusingadata sam-ple ofB0

s→J/ψ φ (1020)→

μ

+

μ

−K+K− decays.The analysed data set corresponds to an integrated

luminosity of 19.7 fb−1 collected in pp collisions at a centre-of-mass energy of 8 TeV. A total of 49 200 reconstructedB0

s decays are used toextract the values ofφs and s by performinga

time-dependentand flavour-taggedangularanalysisofthe

μ

+

μ

−K+K− finalstate.Theweakphaseis mea-sured to be φs= −0.075±0.097(stat)±0.031(syst) rad, and the decaywidth difference is s=

0.095_±0.013(stat)±0.007(syst)ps−1_.

©2016CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.Thisisanopenaccess articleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

1. Introduction

Whilenodirectevidenceofphysicsbeyondthestandardmodel (SM)hasyetbeenfoundattheCERNLHC,theB0_s mesonprovides arich source ofpossibilities to probeits consistency. In this Let-ter,ameasurementoftheweakphase

φ

softheB0s mesonandthe

decaywidthdifference



sbetweenthelightandheavyB0s mass

eigenstatesis presented,usingthedata collectedby theCMS ex-perimentinppcollisionsattheLHCwithacentre-of-massenergy of8TeV,correspondingtoanintegratedluminosityof19

.

7fb−1.

The CP-violating weak phase

φ

s originates from the

interfer-ence betweendirect B0_s meson decays into a CP eigenstate ccss and decays through B0s–B0s mixing to the same final state.

Ne-glectingpenguin diagram contributions [1,2],

φ

s isrelatedto the

elementsoftheCabibbo–Kobayashi–Maskawaquarkmixingmatrix by

φ

s

 −

2

β

s,where

β

s

=

arg

(

−

VtsV_tb∗

/

VcsV_cb∗

)

.Thepredictionfor

2

β

s, determined via a global fit to experimental data within the

SM, is 2

β

s

=

0

.

0363+₋0_0..0016₀₀₁₅ rad [3]. Since the value predicted by

theSM isvery precise,anysignificant deviationofthe measured value fromthispredictionwouldbe particularlyinteresting, asit wouldindicate apossiblecontributionofnew,unknown particles to the loop diagrams describing B0

s mixing. The theoretical

pre-dictionforthedecaywidthdifference



s betweenthelight and

 _{E-mailaddress:[email protected].}

heavyB0_s masseigenstatesBLandBH,assumingnonewphysicsin

B0_s–B0_s mixing,is



s

= L

− H

=

0

.

087

±

0

.

021 ps−1[4].

Theweak phase

φ

s was firstmeasured bytheTevatron

exper-iments [5–8], and then at the LHC by the LHCb and ATLAS ex-periments[9–13],usingB0

s

→

J

/ψ φ(

1020

)

,B0s

→

J

/ψ

f0

(

980

)

,and

B0

s

→

J

/ψ

π

+

π

−decaysto

+

−h+h−,where

denotesamuonin

thepresentanalysisandhstandsforakaonorapion.Finalstates thatdonothaveasingleCPeigenvaluerequireanangularanalysis to disentangle the CP-odd and CP-even components. The time-dependent angular analysis can be performed by measuring the decayanglesofthefinal-stateparticles

+

−h+h−andtheproper decay time of the B0s multiplied by the speed of light [14],

re-ferredtoasct inwhatfollows.InthisLetter,theB0_s

→

J

/ψ φ(

1020

)

decaytothefinalstate

μ

+

μ

−K+K−isanalysed,andpossible ad-ditional contributions to the result from the nonresonant decay B0_s

→

J

/ψ

K+K− aretakenintoaccountbyincludingatermforan additionalamplitude(S-wave)inthefit.

In this measurement the transversity basis is used [14]. The three angles

= (θT

,

ψ

T

,

ϕ

T

)

of the transversity basis are

illus-tratedinFig. 1.Theangles

θ

Tand

ϕ

T arethepolarandazimuthal

angles,respectively,ofthe

μ

+intherestframeoftheJ

/ψ

where thex axisisdefinedbythedirectionofthe

φ (

1020

)

mesoninthe J

/ψ

restframe,andthex– y planeisdefinedbythedecayplaneof the

φ (

1020

)

→

K+K−.Thehelicityangle

ψ

TistheangleoftheK+

in the

φ (

1020

)

restframe with respectto the negative J

/ψ

mo-mentumdirection.

http://dx.doi.org/10.1016/j.physletb.2016.03.046

0370-2693/©2016CERNforthebenefitoftheCMSCollaboration.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

Table 1

Angularandtime-dependenttermsofthesignalmodel.

i gi(θT, ψT,ϕT) Ni ai bi ci di

1 2 cos2

ψT(1−sin2θTcos2ϕT) |A0(0)|2 1 D C −S

2 sin2ψT(1−sin2θTsin2ϕT) |A(0)|2 _{1 D C −S}

3 sin2_ψ

Tsin2θT |A⊥(0)|2 _{1 −D C S}

4 −sin2ψTsin 2θTsinϕT |A(0)||A⊥(0)| C sin(δ⊥− δ) S cos(δ⊥− δ) sin(δ⊥− δ) D cos(δ⊥− δ)

5 _√1

2sin 2ψTsin 2

θTsin 2ϕT |A0(0)||A(0)| cos(δ− δ0) D cos(δ− δ0) C cos(δ− δ0) −S cos(δ− δ0)

6 _√1

2sin 2ψTsin 2θTsinϕT |A0(0)||A⊥(0)| C sin(δ⊥− δ0) S cos(δ⊥− δ0) sin(δ⊥− δ0) D cos(δ⊥− δ0)

7 23(1−sin 2 θTcos2ϕT) |AS(0)|2 1 −D C S 8 1 3 √

6 sinψTsin2θTsin 2ϕT |AS(0)||A(0)| C cos(δ− δS) S sin(δ− δS) cos(δ− δS) D sin(δ− δS)

9 1

3

√

6 sinψTsin 2θTcosϕT |AS(0)||A⊥(0)| sin(δ⊥− δS) −D sin(δ⊥− δS) C sin(δ⊥− δS) S sin(δ⊥− δS)

10 43

√

3 cosψT(1−sin2θTcos2ϕT) |AS(0)||A0(0)| C cos(δ0− δS) S sin(δ0− δS) cos(δ0− δS) D sin(δ0− δS)

Fig. 1. DefinitionofthethreeanglesθT,ψT,andϕTdescribingthedecaytopology

ofB0

s→J/ψ φ(1020).Seetextfordetails.

ThedifferentialdecayrateofB0_s

→

J

/ψ φ(

1020

)

isrepresented usingthefunction f

(,

ct

,

α

)

asinRef.[15]:

d4





B0_s



d

d

(

ct

)

=

f

(,

ct

,

α)

∝

10



i=1 Oi

(

ct

,

α)

gi

(),

(1)

where Oi aretime-dependent functions, gi areangularfunctions,

and

α

isasetofphysicsparameters. Thefunctions Oi

(

ct

,

α

)

are:

Oi

(

ct

,α)

=

Nie−ct/cτ



aicosh





st 2



+

bisinh





st 2



+

cicos

(

mst

)

+

disin

(

mst

)



,

where



msisthemassdifferencebetweentheheavyandlightB0s

masseigenstates,c

τ

isdefinedastheproductofthelifetimeand thespeedoflight,thefunction gi

()

andthetermsNi,ai,bi,ci,

anddiaregiveninTable 1.

ThetermsC , S,andD aredefinedas:

C

=

1

− |λ|

2 1

+ |λ|

2

,

S

= −

2

|λ|

sin

φ

s 1

+ |λ|

2

,

D

= −

2

|λ|

cos

φ

s 1

+ |λ|

2

,

using the same sign convention as the LHCb experiment [10]. Equation(1)representsthemodelforB0

s.ThemodelforB0s is

ob-tainedbychangingthesignoftheciandditerms.Theparameters

|

A_⊥

|

2_,

_|

_A0|2_,and

_|

_A



|

2arethemagnitudessquaredofthe perpen-dicular,longitudinal,andparallel P -waveamplitudes,respectively;

|

AS

|

2 is the magnitude squared of the S-wave amplitude

repre-sentingthefractionofnonresonantdecayB0

s

→

J

/ψ

K+K−;the

pa-rameters

δ

_⊥,

δ

0,

δ

,and

δ

S aretheircorrespondingstrongphases.

Thecomplexparameters

λ

f aredefinedas

λ

f

= (

q

/

p

)(

Af

/

Af

)

,

wheretheamplitudesAf

(

Af

)

describethedecayofaB0s (B0s)

me-sontoafinalstate f ,andtheparameters p andq relatethemass andflavoureigenstatesasBH

=

pB0s

−

qBs0 andBL

=

pB0s

+

qB0s [16].

Assumingpolarisation-independentCP-violationeffects,

λ

f canbe

simplifiedas

λ

f

=

η

f

λ

,where

η

f istheCPeigenvalue.Theamount

ofCPviolationinmixingisassumedtobenegligible[17].Thus,no

|

q

/

p

|

termsareusedinEq.(1)whengoingfromtheB0

s modelto

theB0_s model.SincedirectCPviolationisexpectedtobesmall the-oretically[3]andismeasuredtobesmall[9],

|λ|

issetto1.0. 2. TheCMSdetector

ThecentralfeatureoftheCMSapparatusisa13 m long super-conductingsolenoidof6 m internaldiameter,providingamagnetic field of3.8 T. Withinthe solenoidvolumeare a siliconpixeland strip tracker,a lead tungstatecrystalelectromagneticcalorimeter, andabrassandscintillatorhadroncalorimeter,eachcomposedof a barrel and two endcap sections. Muons are measured in gas-ionisationdetectorsembeddedinthesteelflux-returnyokeoutside thesolenoid.Extensiveforwardcalorimetrycomplementsthe cov-erageprovidedbythebarrelandendcapdetectors.

The main subdetectors used for the present analysis are the silicon tracker and the muon detection system. The sili-contrackermeasures chargedparticles withinthe pseudorapidity range

|

η

| <

2

.

5.Itconsistsof66million100

×

150μm2_silicon

pix-elsandmorethan9millionsiliconstrips.Fornonisolatedparticles oftransversemomentum1

<

pT

<

10GeV and

|

η

|

<

1

.

4,thetrack

resolutionsaretypically1.5%in pT and25–90(45–150)μminthe

transverse(longitudinal)impactparameter[18].

Muons are measured in the pseudorapidity range

|

η

|

<

2

.

4, withdetectionplanesmadeusing threetechnologies:drift tubes, cathode strip chambers, and resistive plate chambers. The rel-ative pT resolution for low transverse momentum muons with

pT

<

10GeV isbetween0.8%and3.0%dependingon

|

η

|

[19].

Thefirstlevel(L1)oftheCMStriggersystem,composedof cus-tom hardware processors,uses informationfromthecalorimeters andmuondetectorstoselectthemostinterestingeventsinafixed timeintervaloflessthan4μs.Thehigh-leveltrigger(HLT) proces-sor farm furtherreduces theevent ratefromaround 100 kHz to around 400 Hz,beforedatastorage.At theHLTstagethereis full accesstoall theeventinformation,includingtracking,and there-foreselectionssimilartothoseappliedofflinecanbeused.

AmoredetaileddescriptionoftheCMSdetector,togetherwith a definitionofthecoordinatesystemusedandtherelevant kine-maticvariables,canbefoundinRef.[20].

3. Eventselectionandsimulatedsamples

A trigger optimised for the detection of B hadrons decaying to J

/ψ

is used to collect the data sample. The L1 trigger used in this analysis requires two muons, each with pT greater than

3 GeV and

|

η

|

<

2

.

1.The HLTrequires aJ

/ψ

candidatedisplaced from the luminous region. Each muon pT is required to be at

greaterthan 6.9 GeV.The J

/ψ

candidates are reconstructedfrom themuon pairsselectedbythetriggerintheinvariantmass win-dow2.9–3.3 GeV. The three-dimensional(3D) distanceof closest approachofthetwomuonstoeachotherisrequiredtobesmaller than 0

.

5 cm. The two muon trajectoriesare fittedto a common decayvertex.The transversedecaylength significance Lxy

/

σ

Lxy is

requiredtobe greaterthan 3,whereLxy isthe distancebetween

thecentreoftheluminousregionandthesecondaryvertexinthe transverseplane, and

σ

Lxy isthe Lxy uncertainty.The

secondary-vertexfitprobability,calculatedusing the

χ

2 _{andthenumberof}

degreesof freedom of the vertex fit, must be greater than 10%. Theangle

ρ

betweenthedimuontransverse momentumandthe Lxydirectionisrequiredtosatisfycos

ρ

>

0

.

9.

Offline selection criteria are applied to the sample. The indi-vidual muon candidates are required to lie within a kinematic acceptance region of pT

>

4 GeV and

|

η

|

<

2

.

1. Two oppositely

chargedmuoncandidatesarepairedandrequiredtooriginatefrom acommonvertex.Dimuon candidateswithinvariantmass within 150 MeV of the world-average J

/ψ

mass [21] are selected. Can-didate

φ (

1020

)

mesonsarereconstructedfrompairsofoppositely chargedtracks withpT

>

0

.

7GeV,afterremovingthe muon

can-didatetracksforming the J

/ψ

.Eachselected trackis assumedto beakaon,andtheinvariantmassofatrackpairisrequiredtobe within10 MeV oftheworld-average

φ (

1020

)

mass[21].

TheB0s candidatesare formed bycombining J

/ψ

and

φ (

1020

)

candidates.A kinematic fit ofthe two muon andtwo kaon can-didatesisperformed,withacommonvertex,andthedimuon in-variantmass is constrained to the nominal J

/ψ

mass [21]. A B0_s candidateisretainediftheJ

/ψ φ(

1020

)

pairhasaninvariantmass between5.20 and 5.65 GeV and the

χ

2 _{vertex fit probability is}

greaterthan2%.

Multiple pp collisions can occur in the same beam crossing (pileup).Theaveragenumberofprimaryverticesinaneventis ap-proximately16,andeachselectedeventisrequiredtohaveatleast one reconstructed primary vertex. If there are multiple vertices, theonethatminimisestheanglebetweentheflightdirectionand themomentumoftheB0

s isselected.Theselectedprimary vertex

isusedtomeasurect.Thequantityct iscalculatedfromthe trans-versedecaylengthvector oftheB0s,

L

B0 s xy,asct

=

m B0 s PDG

L B0 s xy

·

pT

/

p2T, wheremB0s

PDG isthe world-average B0s mass [21] and

pT isthe B0s

transversemomentumvector.Thedecaylengthiscalculatedinthe transverseplanetominimiseeffectsduetopileup.

Simulatedeventsareproduced usingthe pythia v6.424Monte Carloeventgenerator[22].TheBhadrondecaysaremodelledwith the evtgen simulationpackage[23].FortheB0_s signalgeneration, the evtpvvcplh moduleisused,whichsimulatesthedoublevector decaytakinginto accountneutralmesonmixingandCP-violating time-dependent asymmetries. Final-state radiation is included in evtgen _{throughthe photos package[24,25].The eventsare then} passed through a detailed Geant4-based simulation [26] of the CMSdetector.Thepredicteddistributionsfromsimulationofmany kinematic and geometric variables are compared to those from data and found to be in agreement. The simulated samples are used to determine the signal reconstruction efficiencies, and to studythebackgroundcomponentsintheB0_s signalmasswindow.

The main backgroundfor the B0_s

→

J

/ψ φ(

1020

)

decays origi-natesfromnonprompt J

/ψ

mesonsfromthe decayofB hadrons, suchasB0_,B±_,

_

b,andBc.SincetheBccrosssectionissmall[21]

comparedtothat ofthe B0_s [21],the Bc decays canbe neglected.

Thecontributionofthe



b

→

J

/ψ

X channelstotheselectedevents

isalsofoundtobesmall,anditsmassdistributionintheselected massrangeisobservedtobeflat.Theeffectofbackgroundwitha similarsignalsignatureonthephysicsobservablesisstudiedusing simulatedevents, andfound to be negligible. The mass

distribu-Fig. 2. TheJ/ψK+K−invariantmassdistributionoftheB0

scandidates.Thesolidline

isafittothedata(solidmarkers),thedashedlineisthesignalcomponentandthe dot-dashedlineisthebackgroundcomponent.

tioninthesignalregionisshowninFig. 2,andthedistributionof ct anditsuncertainty

σ

ct inFig. 3.

Efficiencycorrectionsowingtothedetectoracceptance,trigger selection, and selection criteria applied in the data analysis are taken into account in the modelling of the angular observables. The angular efficiency



()

is calculated using a fully simulated sample ofB0_s

→

J

/ψ φ(

1020

)

→

μ

+

μ

−K+K− decays. Inthis sam-ple,the



sparameterissettozerotoavoidcorrelationsbetween

thedecay timeandthe angularvariables.The



()

is fittedtoa 3D function of

to properly account forthe correlation among theangularobservables.

Thetriggerincludesadecaylengthsignificancerequirementfor the J

/ψ

candidates.Accordingly, thevalue ofct is requiredtobe greaterthan200 μminordertoavoidalifetimebiascomingfrom theturn-oncurveofthetriggerefficiency.Theefficiencyhistogram ofct isthenfittedwithastraightlineplusasigmoidfunction. 4. Flavourtagging

The flavour of each B0

s candidate atproduction time is

deter-minedwithanopposite-side(OS)flavourtaggingalgorithm.Since b quarks are produced as bb pairs,

¯

the flavour of the signal B0 s

mesonatproductiontimecan beinferredfromtheflavour ofthe other B hadron in the event. The tagging algorithm used in this analysisrequiresanadditionalmuonorelectronintheevents con-taining a reconstructed B0

s

→

J

/ψ φ(

1020

)

decay. The additional

lepton is assumed to originate froma semileptonic decay ofthe OSB hadron,b

→

ν

X decay, with

=

e

,

μ

.Forallthe eventsin whichanOStagleptonisfound thealgorithmprovidesatag de-cision

ξ

basedon thecharge ofthelepton:

ξ

= +

1 forsignalB0

s,

and

ξ

= −

1 forsignalB0_s.

The tag decision is affected by processes that reverse the charge-flavour correlation, such ascascadedecays b

→

c

→

, or semileptonicdecaysofneutralOSB mesonsthathaveoscillatedto theirantiparticlesbeforedecaying.Leptonsproducedfrom flavour-uncorrelatedsources,suchassemileptonicdecaysofpromptly pro-duced charmedhadrons, pionand kaon decays, J

/ψ

decays, and Dalitz decays of neutral pions further contribute to diluting the tag information. The probability of assigning a wrong flavour to thesignal B0_s isdescribed bythemistagprobability

ω

,definedas theratio ofthenumberofwrongly taggedeventsdivided by the totalnumberoftaggedevents,whichisdirectlyrelatedtothe

di-Fig. 3. Thect distribution(top)anditsuncertaintyσct (bottom)oftheB0s

candi-dates.Thesolidlineisafittothedata(solidmarkers),thedashedlineisthesignal componentandthedot-dashedlineisthebackgroundcomponent.Forthect dis-tributionthepull,definedasthedifferencebetweentheobservedeventsandthe fitfunctionappliedtothesumofthesignalandbackground,dividedbythe statis-ticaluncertaintyintheobservedevents,isdisplayedinthehistograminthelower panel.

lutionfactorD

= (

1

−

2

ω

)

.Thevalueof

ω

isestimatedfromdata onaper-eventbasis,asdescribedbelow.

Thetaggingalgorithm isoptimised bymaximisingthe tagging power

P

tag

=

ε

tag

(

1

−

2

ω

)

2,which representstheequivalent

effi-ciencyofa sample withperfecttagging (

ω

=

0).The term

ε

tag is

thetaggingefficiency,definedasthefractionofeventstowhicha tagdecisionisfoundbythetaggingalgorithm.

Opposite-sidemuonsandelectrons arereconstructed withthe particle-flow algorithm [27,28]. In each event, the muons (elec-trons) that are not part of the reconstructed B0

s

→

J

/ψ φ(

1020

)

decay are required to be identified withloose identification cri-teria.Iftherearemultiplemuons(electrons)intheevent,theone withthehighest pT is chosenatthisstage. Thetag lepton

selec-tionsarethenoptimisedseparatelyformuonsandelectronsusing simulatedsignalsamplesofB0

s

→

J

/ψ φ(

1020

)

decays.Acut-based

opposite-side lepton selection is applied to reduce the number ofleptons not originatingfromB-hadron decays.To optimise the selection, severalvariables arestudied, anda setof five

discrim-inating variables (pT,

η

, dxyz,



R, Isolation) is identified. A total

number of more than four million alternative cut configurations have been tested to determine the configuration that maximises the tagging power, independently for muons and electrons. The tag muon is thus required to have pT

>

2

.

2 GeV, the3D impact

parameterdxyzwithrespecttotheprimaryvertexassociatedwith

the signal B0_s isrequired tobe smaller than 0

.

1 cm, andthe an-gular separation,



R

=

(φ)

2

_{+ (}

_η

₎

2_{, betweenthemuon and}

thesignalB0_s isrequiredtobegreaterthan0.3,where

φ

and



η

are the azimuthal angle and pseudorapidity differences between the directions of the tag muon and the B0_s candidate. Electrons are requiredtohave pT

>

2

.

0GeV,dxyz

<

0

.

1 cm,and



R

>

0

.

2.

Inaddition,amultivariatediscriminator(MVAe−π )tunedto sepa-rategenuineelectronsreconstructedbytheparticle-flowalgorithm from pions and photons is applied to tag electrons by requiring thatthediscriminatorisgreaterthan0.2[28].

Amultilayerperceptronneuralnetwork(MLP-NN)oftheTMVA toolkit [29] is usedto further separate theright- and wrong-tag leptons. Training and testing is performed using approximately 24 000 and 20 400 simulated B0s

→

J

/ψ φ(

1020

)

events for the

muon andelectronMLP-NNs,respectively,andtwoindependently optimised setsofvariables.Halfofeach sampleis usedfor train-ing andtheother halffortesting.Theinput variablescommonto bothMLP-NNsare pT,

η

,anddxyz ofthetaglepton,andtwo

vari-ables related toactivity ina cone around thelepton direction: a particle-flowrelativeisolationvariable[28]anda pT-weighted

av-erageofthechargesoftheparticlesinthecone.Specificvariables are further introducedin theMLP-NNs separately formuonsand electrons.Formuons,thepTrelativetotheaxisofthejet

contain-ingthemuonisused,whileforelectronstheMVAe−π isexploited. Themistagprobabilitiesareobtainedfromdatausingthe self-tagging channel B±

→

J

/ψ

K±, where the charge of the recon-structedkaondeterminestheflavouroftheB±and,intheabsence ofmixing,oftheopposite-sideBhadronaswell.Themistag prob-abilitiesareparametrisedseparatelyformuonsandelectronswith analytic functions ofthe MLP-NN discriminatorsin orderto pro-vide a per-eventvalue ofthepredictedmistagprobability

ω

.The functional forms of the parametrisations are obtained from the simulated B0

s sample. The candidate B± mesons are required to

pass a selectionassimilar aspossible tothat applied forthe re-construction of the signal B0s candidates. The same trigger and

J

/ψ

reconstruction requirements as forthe B0

s signal sample are

applied. A charged particle with pT

>

2 GeV, assumed to be a

kaon,iscombinedwiththedimuonpairinakinematicfit.An un-binned extended maximum-likelihoodfit to the invariant J

/ψ

K± massisperformed,yieldingatotalof

(

707

±

2

)

×

103 reconstructed B±

→

J

/ψ

K± events. The tagging efficiency evaluated with the B±

→

J

/ψ

K± data sample is

(

4

.

56

±

0

.

02

)

% and

(

3

.

92

±

0

.

02

)

% formuonsandelectrons,respectively,wheretheuncertainties are statistical.

Themistagparametrisationcurvesevaluated withtheB± con-trolchannel for muonsandelectrons are showninFig. 4,where the parametrisations for the B± and B0_s simulated samples are shownforcomparison.

Most tagged events have only a single electron or muon tag. If both tags are available fora specific event (about 3.5% of the cases), thetag leptonwith thegreatestvalue of thedilution fac-torisretained,andthetagdecisionandtheestimatedmistagare takenfromthistaglepton.The overallleptontaggingefficiencyis

(

8

.

31

±

0

.

03

)

%, asmeasured in data withthe B±

→

J

/ψ

K± data sample.

To correctfor potential effects induced by thedependence of the tagging algorithm on the B0

s

→

J

/ψ φ(

1020

)

simulation, the

mistag probability is calibrated by comparing the per-event pre-dicted

ω

to themeasured

ω

meas _{obtainedfromtheB}±

_→

_J

_/ψ

_K±

Fig. 4. Themistagprobabilitiesω,definedastheratioofthenumberofwrongly taggedeventsdividedbythetotalnumberoftaggedevents,asafunctionofthe MLP-NNdiscriminatorsfor muons(top)andelectrons (bottom).The datapoints (solidmarkers) areplacedat the averageweightedvalue oftheeventsineach bin. Theverticalbars showthe statistical uncertaintiesand the horizontal bars thebinwidth.Thesolidlinerepresentstheparametrisationcurveextractedfrom thebackground-subtractedB±data;thedashedanddot-dashedlinesrefertothe parametrisationsextractedfromthesimulatedB0

sandB±samples,respectively.

data control channel. This is then fit to the function

ω

meas

₌

p0

+

p1

(

ω

−

ω

)

,chosentolimitthecorrelationbetweenthe

func-tionparameters p0 and p1. Theparameter

ω

is fixedto a value

roughlycorrespondingtothemeanofthecalculatedmistag prob-ability,

ω

=

0

.

35. The resulting calibration parameters are p0

=

0

.

348

±

0

.

003 and p1

=

1

.

01

±

0

.

03, and their uncertainties are

propagatedasastatisticaluncertaintyintheOStagger.

Thesystematic uncertainties relatedto the calibration param-eters p0 and p1 are dominated by the dependenceof these

pa-rameters on the flavour of the signal-side B hadron. The uncer-taintiesareestimatedfromB± dataandsimulatedsamplesofB0 s

andB± events.Systematicuncertaintiesoriginatingfrompossible variationsinthe CMSdata-takingconditions,thesignal B hadron kinematics,theanalytic formofthemistag parametrisation func-tions,andthemodelusedtofittheB±invariantmassdistribution aretestedandfoundtobenegligible.

The overall tagging power of the OS lepton tagger, mea-suredwith a sample of B±

→

J

/ψ

K± events, is

P

tag

= (

1

.

307

±

0

.

031

(

stat

)

±

0

.

007

(

syst

))

%,correspondingtothecombinedmistag probability

ω

= (

30

.

17

±

0

.

24

(

stat

)

±

0

.

05

(

syst

))

%.

5. Maximum-likelihoodfit

Anunbinnedmaximum-likelihoodfitto thedataisperformed by includingtheinformationon theB0

s invariant mass(mB0 s), the

three decay angles (

) of the reconstructed B0_s candidates, the flavour tag decision (

ξ

), ct, and

σ

ct, obtained by summing in

quadraturethedecaylengthuncertaintyandtheuncertaintyinthe transversemomentum. Thefit isappliedto thesample of70500 events,outofwhich5650 aretaggedevents,selectedinthemass range 5.24–5.49 GeV andct

=

200–3000μm. From this multidi-mensional fit,the physics parameters of interest



s,

φ

s, theB0s

mean lifetime c

τ

,

|

A_⊥

|

2,

|

A0|2,

|

AS

|

2, and the strong phases

δ

,

δ

⊥,and

δ

S⊥ are determined, where

δ

S⊥ is definedas the

differ-ence

δ

S

− δ

⊥.The P-waveamplitudes arenormalised to unityby constraining

|

A_

|

2 to1

− |

A_⊥

|

2

− |

A0|2.Thefitmodelisvalidated with simulated pseudo-experimentsand with simulated samples withdifferentparametersets.

Thelikelihoodfunctioniscomposedofprobabilitydensity func-tions(pdf)describingthesignalandbackgroundcomponents.The likelihood fit algorithm is implemented using the RooFit pack-age from the ROOT framework [30]. The signal and background pdfs are formed as the product ofpdfs that modelthe invariant mass distribution andthe time-dependent decayrates of the re-constructed candidates. In addition, the signal pdf also includes the efficiencyfunction. The eventlikelihood function

L

is repre-sented as:

L

=

Ls

+

Lbkg

,

Ls

=

Ns

˜

f

(,

ct

,α)

⊗

G

(

ct

,σ

ct

)



()



×

Ps

(

mB0 s

)

Ps

(σ

ct

)

Ps

(ξ ),

Lbkg

=

NbkgPbkg

(

cos

θ

T

,

ϕ

T

)

Pbkg

(

cos

ψ

T

)

Pbkg

(

ct

)

×

Pbkg

(

mB0 s

)

Pbkg

(σ

ct

)

Pbkg

(ξ ),

whereLsandLbkgarethepdfsthatdescribetheB0s

→

J

/ψ φ(

1020

)

signal andbackgroundcontributions, respectively. Thenumber of signal(background)eventsisNs (Nbkg).Thepdf

˜

f

(,

ct

,

α

)

isthe

differentialdecayratefunction f

(,

ct

,

α

)

definedinEq.(1), mod-ified to include the flavour tagging information and the dilution term

(

1

−

2

ω

)

,whichare applied toeach ofthe ci anddi terms

oftheequation.Inthe

˜

f expression,thevalueof

δ

0issettozero,

following ageneral convention. Thefunction



()

isthe angular efficiency and G

(

ct

,

σ

ct

)

isa Gaussian resolution function, which

makesuseoftheevent-by-eventdecaytimeuncertainty

σ

ct,scaled

byafactor

κ

.The

κ

factorisafunctionofct andisintroducedas a correctionto take careofresidual effectswhen thedecaytime uncertaintyisusedtomodelthect resolution.The function

κ

(

ct

)

is measured using simulated samples and, on average, its value equals1.0towithinafewpercent.Theaveragedecaytime uncer-taintyincludingthe

κ

(

ct

)

factorequals23.4 μm.Alltheparameters of the pdfs are left free to float in the final fit, unless explicitly statedotherwise. The value of



s is constrainedto be positive,

basedonrecentmeasurements[31]. Thesignalmasspdf Ps

(

m_B0

s

)

isthesumofthreeGaussian

func-tions witha common mean; the two smaller widths, the mean, andthefractionofeachGaussian functionarefixed tothevalues obtainedinaone-dimensionalmassfit.Thebackgroundmass dis-tribution Pbkg

(

mB0

s

)

is described by an exponential function. The

background decay time component Pbkg

(

ct

)

is described by the

sumoftwo exponentialfunctions. Theangularparts ofthe back-groundspdfs Pbkg

(

cos

θ

T

,

ϕ

T

)

and Pbkg

(

cos

ψ

T

)

aredescribed

Table 2

Resultsofthefittothedata.Uncertaintiesare statisticalonly.

Parameter Fit result

φs[rad] −0.075±0.097 s[ps−1] 0.095±0.013 |A0|2 0.510±0.005 |AS|2 0.012+₋00..009007 |A⊥|2 0.243±0.008 δ[rad] 3.48+0.07 −0.09 δS⊥[rad] 0.37+₋00..2812 δ⊥[rad] 2.98±0.36 cτ[μm] 447.2±2.9

andsinusoidalfunctionsfor

ϕ

T.Forthe cos

θ

T and

ϕ

T variablesa

two-dimensional pdf isused to take intoaccount the correlation amongthevariables.

Thesignal decaytime uncertaintypdf Ps

(

σ

ct

)

isa sumoftwo

Gammafunctions,withalltheparametersfixed tothevalues ob-tained by fitting a sample of background-subtracted events. The backgrounddecaytimeuncertaintypdf Pbkg

(

σ

ct

)

isrepresentedby

aGammafunction.Alltheparameters arefixed tothevalues ob-tainedby fitting the B0

s invariant masssideband regions, defined

bythemassrangesm_B0

s

=

5

.

24–5

.

28GeV and 5.45–5.49 GeV.The

functions Ps

(ξ )

and Pbkg

(ξ )

are the tag decision

ξ

pdfs, which

havebeenobtainedfromthedata. 6. Resultsandsystematicuncertainties

The results of the fit are given in Table 2, where the quoted uncertainties are statistical only. The corresponding correlation matrix forthe statistical uncertainties in the physics fit

parame-ters is showninTable 3. Sincethe likelihood profiles of

δ

,

δ

S⊥, and

|

AS

|

2 are not parabolic, the statistical uncertainties quoted

for these parameters are found from the increase in

−

log

L

by 0.5. In the fit, the value of



ms is allowed to vary following a

Gaussian distribution with mean and standard deviation set to

(

17

.

69

±

0

.

08

)

×

1012_h

_¯

_/

_{s[32].Asacross-check,the}

_

_m

s valueis

alsoleftfreetofloatanditsbestfitvalueisfoundtobein statis-ticalagreementwiththe setvalue.The variousdatadistributions and the fit projections are shown in Figs. 2, 3, and 5. The drop inthecos

θ

T distributionattherangelimitsisidentified asbeing

causedby close-by,high-angle kaontracks.Thecentral valueand the68%,90%,and95%confidencelevel(CL)likelihoodcontoursof thefitinthe



s–

φ

splaneareshowninFig. 6.

Severalsourcesofsystematicuncertaintiesintheprimary mea-sured quantities are investigated by testing the various assump-tions made in the fit model and those associated with the fit procedure.

The systematic uncertaintyassociated withthe assumption of aconstantefficiencyasafunctionofct isevaluatedbyfittingthe datawithanalternativect efficiencyparametrisation,whichtakes into account a small contribution of the decay time significance requirement at small ct and first-order polynomial variations at highct.Thedifferencesfoundinthefitresultswithrespecttothe nominalfitareusedassystematicuncertainties.

The uncertainties associatedwith the variables cos

θ

T

,

ϕ

T,and

cos

ψ

T ofthe3D angularefficiencyfunctionarepropagatedtothe

fit results by varying the corresponding parameters within their statisticaluncertainties,accountingforthecorrelationsamongthe parameters. The maximum variation of the parameters extracted fromthefitistakenasthesystematicuncertainty.Thesystematic uncertaintyowingtoasmalldiscrepancyinthekaonpT spectrum

betweendataandsimulationisevaluatedbyweightingtheevents tomakethesimulatedkaonpTspectrummatchthatindata.

Table 3

Correlationmatrixforthestatisticaluncertaintiesinthephysicsfitparameters.

|A0|2 |AS|2 |A⊥|2 δ δS⊥ δ⊥ cτ s φs |A0|2 +1.00 +0.19 −0.64 −0.08 −0.18 −0.02 +0.38 +0.70 +0.11 |AS|2 – +1.00 −0.02 −0.32 −0.79 −0.10 −0.16 +0.01 +0.03 |A⊥|2 – – +1.00 −0.27 +0.03 −0.06 −0.50 −0.77 −0.11 δ – – – +1.00 +0.26 +0.21 +0.11 +0.03 −0.02 δS⊥ – – – – +1.00 +0.06 +0.11 −0.04 −0.06 δ⊥ – – – – – +1.00 +0.03 +0.01 +0.01 cτ – – – – – – +1.00 +0.55 +0.10 s – – – – – – – +1.00 +0.10 φs – – – – – – – – +1.00

Fig. 5. Theangulardistributions(cosθT,cosψT,ϕT)ofthe B0s candidatesfromdata(solidmarkers).Thesolidlineistheresultofthefit,thedashedlineisthesignal

Fig. 6. TheCMSmeasuredcentralvalueandthe68%,90%,and95%CLcontoursin thesversusφsplane,togetherwiththeSMprediction[3,4].Uncertaintiesare

statisticalonly.

Theuncertaintyinthect resolutionassociatedwiththe

κ

factor ispropagatedtotheresults.Asetoftestsamplesisproducedwith the

κ

(

ct

)

factor varying within their uncertainty, assumed to be Gaussian.Onestandarddeviationofthedistributiondescribingthe differencebetweenthect resolutionwiththenominalfitandwith a varying

κ

(

ct

)

is takenas the systematicuncertainty. Since the

κ

(

ct

)

factorisobtainedfromsimulation,theassociatedsystematic uncertaintyis assessed by using a sample of prompt J

/ψ

decays obtainedwithanunbiasedtriggerandcomparingthemtosimilarly processed simulateddata. In this way the decay time resolution forct

≈

0 isobtained.The

κ

(

ct

)

factorisvariedwithin thevalues observed in data and simulation. The resulting variations of the physicsparametersaretakenassystematicuncertainties.

Although the likelihood function makes use of a per-event mistagparameter,itdoesnot containapdf modelforthemistag distribution. The associated systematic uncertainty is estimated bygeneratingsimulatedpseudo-experimentswithdifferentmistag distributionsforsignalandbackgroundandfittingthemwiththe nominalfit.

The dominant tagging systematic uncertainty originates from theassumption that thesignal andcalibrationchannels havethe sametaggingperformance.Itisevaluatedusingacalibrationcurve, obtainedfromsimulatedsamples,thatdescribesthemistag prob-abilityof B0_s asfunction of the mistag probability of B±. The fit

tothe dataisrepeated, re-calibratingthemistagprobability with the B0_s–B± calibration curve, andthe differencesfound in the fit resultswithrespecttothenominalfitareusedasthesystematic uncertainties.

Possiblebiasesintrinsictothefitmodelarealsotakeninto ac-count. The nominalmodel function is testedby using simulated pseudo-experiments, andtheaverage ofthepulls(defined asthe differencebetweentheresultoffittothepseudo-experiment sam-pleandthenominalvalue)isusedasasystematicuncertaintyifit exceedsonestandarddeviationstatisticaluncertainty.

Thevarioushypothesesthathavebeenassumedwhenbuilding thelikelihoodfunctionaretestedbygeneratingsimulated pseudo-experiments with different hypotheses and fitting the samples withthenominallikelihoodfunction.Theobtainedpullhistograms ofthephysicsvariablesarefittedwithGaussianfunctions,andthe averageofthepullisusedasasystematicuncertaintyifthe differ-encewithrespect to the averageexceeds one standard deviation statisticaluncertainty.Concerningthe modellingoftheJ

/ψ

K+K− invariant mass distribution, the background model ischanged to a Chebyshev function from the nominal exponential pdf. The ct backgroundpdfis changedtothesumofthreeexponential func-tions insteadofthetwo exponentialfunctionsofthe nominalfit. Theangularbackgroundpdfisgeneratedbyusingthebackground simulationangularshapesinsteadofthefitones.Theeffectofnot includingthe angularresolution isalso tested, usingtheresidual distributions obtained from simulations. The RMS of the angular resolutions were found to be 5.9, 6.3, and 10 mrad, for cos

θ

T,

cos

ψ

T,and

ϕ

T respectively.Thecontributiontothesystematic

un-certaintyfromthebackgroundtaggingasymmetryisnegligible. The hypothesis that

|λ|

=

1 is tested by leaving that param-eter free in the fit. The obtained value of

|λ|

is consistent with 1.0within onestandarddeviation.Thedifferencesfoundinthefit resultswithrespecttothenominalfitareusedassystematic un-certainties.

Thealignment systematicuncertaintyaffectsthevertex recon-structionandthereforethedecaytimes.Thateffectisestimatedto be1

.

5 μm fromstudiesofknownBhadronlifetimes[33].The sys-tematic effectowing to the very small numberof B0

s originating

fromB+_c

→

B0

s

π

+feed-down,whichwouldbereconstructedwith

largevaluesofct,hasbeenfoundtobenegligible.

The measured values for the weak phase

φ

s and the decay

widthdifference



s are:

φ

s

= −

0

.

075

±

0

.

097

(

stat

)

±

0

.

031

(

syst

)

rad

,



s

=

0

.

095

±

0

.

013

(

stat

)

±

0

.

007

(

syst

)

ps−1

.

ThesystematicuncertaintiesaresummarisedinTable 4.The uncer-taintiesinthe

φ

sand



s resultsaredominatedbythestatistical

uncertainties.

Table 4

SummaryoftheuncertaintiesinthemeasurementsofthevariousB0

s parameters.Ifnovalueisreported,thenthesystematicuncertaintyisnegligiblewithrespecttothe

statisticalandothersystematicuncertainties.Thetotalsystematicuncertaintyisthequadraticsumofthelistedsystematicuncertainties.

Source of uncertainty φs[rad] s[ps−1] |A0|2 |AS|2 |A⊥|2 δ[rad] δS⊥[rad] δ⊥[rad] cτ[μm]

ct efficiency 0.002 0.0057 0.0015 – 0.0023 – – – 1.0

Angular efficiency 0.016 0.0021 0.0060 0.008 0.0104 0.674 0.14 0.66 0.8

Kaon pTweighting 0.014 0.0015 0.0094 0.020 0.0041 0.085 0.11 0.02 1.1

ct resolution 0.006 0.0021 0.0009 – 0.0008 0.004 – 0.02 2.9

Mistag distribution modelling 0.004 0.0003 0.0006 – – 0.008 0.01 – 0.1

Flavour tagging 0.003 0.0003 – – – 0.006 0.02 – –

Model bias 0.015 0.0012 0.0008 – – 0.025 0.03 – 0.4

pdf modelling assumptions 0.006 0.0021 0.0016 0.002 0.0021 0.010 0.03 0.04 0.2

|λ|as a free parameter 0.015 0.0003 0.0001 0.005 0.0001 0.002 0.01 0.03 –

Tracker alignment – – – – – – – – 1.5

Total systematic uncertainty 0.031 0.0070 0.0114 0.022 0.0116 0.680 0.18 0.66 3.7 Statistical uncertainty 0.097 0.0134 0.0053 0.008 0.0075 0.081 0.17 0.36 2.9

7. Summary

Using pp collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV and corresponding to an inte-grated luminosity of 19

.

7 fb−1, 49 200 B0_s

→

J

/ψ φ(

1020

)

signal candidateswere usedtomeasurethe weakphase

φ

s andthe

de-cay width difference



s. The analysiswas performed by using

opposite-side lepton tagging of the B0_s flavour atthe production time.Bothmuonandelectrontagswereused.

Themeasured valuesfortheweak phaseandthedecaywidth difference between the B0

s mass eigenstates are

φ

s

= −

0

.

075

±

0

.

097

(

stat

)

±

0

.

031

(

syst

)

rad and



s

=

0

.

095

±

0

.

013

(

stat

)

±

0

.

007

(

syst

)

ps−1_{, respectively. The measured values are}

consis-tent with those obtained by the LHCb Collaboration using B0 s

→

J

/ψ

K+K− decays[34].

Ourmeasured valueof

φ

s agrees withtheSM prediction.Our

resultconfirms



s to be nonzero, witha value consistent with

theoreticalpredictions.Theuncertaintiesinour

φ

s and



s

mea-surements are dominated by statisticaluncertainties. Ourresults provideindependentreferencemeasurements of

φ

s and



s,and

contribute to improving the overall precision of these quantities andtherebyprobingtheSMfurther.Sinceourmeasurement preci-sionisstill limitedbystatisticaluncertainty,substantial improve-mentisexpectedfromLHC

√

s

=

13TeV high-luminosity running thatwillbeavailableoverthenextfewyears.

Acknowledgements

WecongratulateourcolleaguesintheCERNaccelerator depart-ments for the excellent performance of the LHC and thank the technicalandadministrativestaffs atCERN andatother CMS in-stitutes for their contributions to the success of the CMS effort. Inaddition,wegratefullyacknowledgethecomputingcentresand personneloftheWorldwideLHCComputingGridfordeliveringso effectivelythe computinginfrastructureessential to ouranalyses. Finally, we acknowledge the enduring support for the construc-tionandoperation oftheLHCandthe CMSdetectorprovidedby 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 (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 Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technolo-gie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS)oftheCzechRepublic;theCouncilofScienceandIndustrial Research,India;theHOMING PLUSprogrammeoftheFoundation forPolishScience,cofinancedfromEuropean Union,Regional De-velopment Fund;the Compagnia di SanPaolo (Torino); the

Con-sorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); theThalisandAristeiaprogrammescofinancedbyEU-ESFandthe Greek NSRF; the National Priorities Research Program by Qatar NationalResearch Fund;theRachadapisekSompot Fund for Post-doctoral Fellowship,Chulalongkorn University (Thailand);andthe WelchFoundation.

References

[1] B.Bhattacharya,A.Datta,D.London,Reducingpenguinpollution,Int.J.Mod. Phys.A28(2013)1350063,http://dx.doi.org/10.1142/S0217751X13500632. [2] S.Faller,R. Fleischer,T.Mannel,Precisionphysics with B0

s→J/ψφ at the

LHC:thequestfornewphysics,Phys.Rev.D79(2009)014005,http://dx.doi. org/10.1103/PhysRevD.79.014005,arXiv:0810.4248.

[3] J. Charles,O. Deschamps,S. Descotes-Genon, R. Itoh, H.Lacker, A.Menzel, S. Monteil,V.Niess, J. Ocariz, J. Orloff,S. T’Jampens, V.Tisserand, K. Tra-belsi,Predictionsofselectedflavourobservableswithinthe standardmodel, Phys.Rev.D84(2011)033005,http://dx.doi.org/10.1103/PhysRevD.84.033005, arXiv:1106.4041.

[4]A.Lenz,U.Nierste,Numericalupdatesoflifetimesandmixingparametersof Bmesons,in:T.Gershon(Ed.),Proceedingsofthe6thInternationalWorkshop ontheCKMUnitarityTriangle,UniversityofWarwick,UnitedKingdom,2010, arXiv:1102.4274.

[5] T. Aaltonen, et al., CDF Collaboration, First flavor-tagged determination of boundsonmixing-inducedCPviolationinB0

s→J/ψφdecays,Phys.Rev.Lett.

100 (2008) 161802, http://dx.doi.org/10.1103/PhysRevLett.100.161802, arXiv: 0712.2397.

[6] V.M.Abazov,etal.,D0Collaboration,MeasurementofB0

s mixingparameters

fromtheflavor-taggeddecayB0

s→J/ψφ,Phys.Rev.Lett.101(2008)241801,

http://dx.doi.org/10.1103/PhysRevLett.101.241801,arXiv:0802.2255.

[7] T.Aaltonen,etal.,CDFCollaboration,MeasurementoftheCP-violatingphase

βJs/ψ φinB0s→J/ψφ decayswiththeCDFIIdetector,Phys.Rev.D85(2012)

072002,http://dx.doi.org/10.1103/PhysRevD.85.072002,arXiv:1112.1726. [8] V.M.Abazov,etal.,D0Collaboration,MeasurementoftheCP-violatingphase

φJs/ψ φusingtheflavor-taggeddecayBs0→J/ψφin8 fb−1ofpp collisions,Phys.

Rev.D85(2012)032006,http://dx.doi.org/10.1103/PhysRevD.85.032006,arXiv: 1109.3166.

[9] LHCb Collaboration, Measurement of the CP-violating phase φs in B0s →

J/ψπ+π− decays, Phys. Lett. B 736 (2014) 186, http://dx.doi.org/10.1016/ j.physletb.2014.06.079,arXiv:1405.4140.

[10] LHCb Collaboration, Measurement of CP violation and the B0

s meson

de-cay width difference with B0

s →J/ψK+K− and B0s →J/ψπ+π− decays,

Phys.Rev.D87(2013)112010,http://dx.doi.org/10.1103/PhysRevD.87.112010, arXiv:1304.2600.

[11] LHCb Collaboration, Measurement of the CP-violating phase φs in B0s →

J/ψπ+π− decays, Phys. Lett. B 713 (2012) 378, http://dx.doi.org/10.1016/ j.physletb.2012.06.032,arXiv:1204.5675.

[12] ATLAS Collaboration, Time-dependent angular analysis of the decay B0 s→

J/ψφ andextractionofs andthe CP-violatingweakphaseφs byATLAS,

J. HighEnergyPhys.12(2012)072,http://dx.doi.org/10.1007/JHEP12(2012)072, arXiv:1208.0572.

[13] ATLAS Collaboration, Flavor tagged time-dependent angular analysisof the B0

s→J/ψφdecayandextractionofδγsandtheweakphaseφsinATLAS,Phys.

Rev.D90(2014)052007,http://dx.doi.org/10.1103/PhysRevD.90.052007. [14] A.S.Dighe,I.Dunietz,R.Fleischer,ExtractingCKMphasesandB0

s− ¯Bsmixing

parametersfromangulardistributionsofnon-leptonicBdecays,Eur.Phys.J.C 6(1999)647,http://dx.doi.org/10.1007/s100529800954,arXiv:hep-ph/9804253. [15] A.S. Dighe,I.Dunietz,H.J.Lipkin, J.L.Rosner,Angulardistributionsand

life-timedifferencesinB0

s→J/ψφdecays,Phys.Lett.B369(1996)144,http://dx.

doi.org/10.1016/0370-2693(95)01523-X,arXiv:hep-ph/9511363.

[16]G.Branco,L.Lavoura,J.Silva,CPViolation,Int.Ser.Monogr.Phys.,vol. 103, ClarendonPress,Oxford,1999.

[17] LHCbCollaboration,Measurementoftheflavour-specificCP-violating asymme-tryasslinB0s decays,Phys.Lett.B728(2014)607,http://dx.doi.org/10.1016/

j.physletb.2013.12.030,arXiv:1308.1048.

[18] CMS Collaboration, Description and performance of track and primary-vertex reconstruction with the CMS tracker,J. Instrum. 9(2014) P10009,

http://dx.doi.org/10.1088/1748-0221/9/10/P10009,arXiv:1405.6569.

[19] CMSCollaboration,PerformanceofCMSmuonreconstructioninpp collision eventsat√s=7TeV,J.Instrum.7(2012)P10002,http://dx.doi.org/10.1088/ 1748-0221/7/10/P10002,arXiv:1206.4071.

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

[21] ParticleDataGroup,K.A.Olive,etal.,Reviewofparticlephysics,Chin.Phys.C 38(2014)090001,http://dx.doi.org/10.1088/1674-1137/38/9/090001. [22] T.Sjöstrand, S.Mrenna, P.Z.Skands,PYTHIA6.4physicsandmanual,J.High

EnergyPhys.05(2006)026,http://dx.doi.org/10.1088/1126-6708/2006/05/026, arXiv:hep-ph/0603175.

[23] D.J.Lange,TheEvtGenparticledecaysimulationpackage,Nucl.Instrum. Meth-odsPhys.Res.,Sect.A,Accel.Spectrom.Detect.Assoc.Equip.462(2001)152,

http://dx.doi.org/10.1016/S0168-9002(01)00089-4.

[24] E.Barberio,B.vanEijk,Z.Was,PHOTOS–auniversalMonte Carlo forQED ra-diativecorrectionsindecays,Comput.Phys.Commun.66(1991)115,http://dx. doi.org/10.1016/0010-4655(91)90012-A.

[25] E.Barberio,Z.W ˛as,PHOTOS–auniversalMonteCarloforQEDradiative cor-rections:version2.0,Comput.Phys.Commun.79(1994)291,http://dx.doi.org/ 10.1016/0010-4655(94)90074-4.

[26] S.Agostinelli,etal.,GEANT4Collaboration,GEANT4—asimulationtoolkit,Nucl. Instrum.MethodsPhys.Res.,Sect.A,Accel.Spectrom.Detect.Assoc.Equip.506 (2003)250,http://dx.doi.org/10.1016/S0168-9002(03)01368-8.

[27] CMSCollaboration,Particle–floweventreconstructioninCMSandperformance forjets,taus,andEmiss

T ,CMSPhysicsAnalysisSummaryCMS-PAS-PFT-09-001,

http://cdsweb.cern.ch/record/1194487,2009.

[28] CMSCollaboration, Commissioningoftheparticle-flowevent reconstruction withthefirstLHCcollisionsrecordedintheCMSdetector,CMSPhysics Anal-ysis Summary CMS-PAS-PFT-10-001, http://cdsweb.cern.ch/record/1247373, 2010.

[29] H.Voss,A.Höcker,J.Stelzer,F.Tegenfeldt,TMVA, thetoolkitfor multivari-ate data analysiswithROOT, in:XIthInternational Workshopon Advanced ComputingandAnalysisTechniquesinPhysicsResearch(ACAT),2007,p. 40,

http://pos.sissa.it/archive/conferences/050/040/ACAT_040.pdf, arXiv:physics/ 0703039.

[30] I.Antcheva,etal., ROOT—AC++frameworkforpetabytedatastorage, sta-tistical analysisand visualization,Comput.Phys.Commun.180(2009)2499,

http://dx.doi.org/10.1016/j.cpc.2009.08.005.

[31] LHCb Collaboration, Determination of the sign of the decay width differ-ence intheB0

s system,Phys. Rev.Lett.108(2012)241801,http://dx.doi.org/

10.1103/PhysRevLett.108.241801,arXiv:1202.4717.

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

[33] CMS√ Collaboration, Measurement of the 0b lifetime in pp collisions at

s=7TeV, J. HighEnergy Phys. 07 (2013)163, http://dx.doi.org/10.1007/ JHEP07(2013)163.

[34] LHCb Collaboration, Precision measurement of CP violation in B0 s →

J/ψk+k−decays,Phys.Rev.Lett.114(2015)041801,http://dx.doi.org/10.1103/ PhysRevLett.114.041801,arXiv:1411.3104.

CMSCollaboration

V. Khachatryan,

A.M. Sirunyan,

A. Tumasyan

YerevanPhysicsInstitute,Yerevan,Armenia

W. Adam,

E. Asilar,

T. Bergauer,

J. Brandstetter,

E. Brondolin,

M. Dragicevic,

J. Erö,

M. Flechl,

M. Friedl,

R. Frühwirth

1

,

V.M. Ghete,

C. Hartl,

N. Hörmann,

J. Hrubec,

M. Jeitler

1

,

V. Knünz,

A. König,

M. Krammer

1

,

I. Krätschmer,

D. Liko,

T. Matsushita,

I. Mikulec,

D. Rabady

2

,

B. Rahbaran,

H. Rohringer,

J. Schieck

1

,

R. Schöfbeck,

J. Strauss,

W. Treberer-Treberspurg,

W. Waltenberger,

C.-E. Wulz

1

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,

S. Ochesanu,

R. Rougny,

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,

H. Delannoy,

G. Fasanella,

L. Favart,

A.P.R. Gay,

A. Grebenyuk,

G. Karapostoli,

T. Lenzi,

A. Léonard,

T. Maerschalk,

A. Marinov,

L. Perniè,

A. Randle-conde,

T. Reis,

T. Seva,

C. Vander Velde,

P. Vanlaer,

R. Yonamine,

F. Zenoni,

F. Zhang

3

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,

N. Strobbe,

M. Tytgat,

W. Van Driessche,

E. Yazgan,

N. Zaganidis

GhentUniversity,Ghent,Belgium

S. Basegmez,

C. Beluffi

4

,

O. Bondu,

S. Brochet,

G. Bruno,

R. Castello,

A. Caudron,

L. Ceard,

V. Lemaitre,

A. Mertens,

C. Nuttens,

L. Perrini,

A. Pin,

K. Piotrzkowski,

A. Popov

6

,

L. Quertenmont,

M. Selvaggi,

M. Vidal Marono

UniversitéCatholiquedeLouvain,Louvain-la-Neuve,Belgium

N. Beliy,

G.H. Hammad

UniversitédeMons,Mons,Belgium

W.L. Aldá Júnior,

G.A. Alves,

L. Brito,

M. Correa Martins Junior,

M. Hamer,

C. Hensel,

C. Mora Herrera,

A. Moraes,

M.E. Pol,

P. Rebello Teles

CentroBrasileirodePesquisasFisicas,RiodeJaneiro,Brazil

E. Belchior Batista Das Chagas,

W. Carvalho,

J. Chinellato

7

,

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,

L. Mundim,

H. Nogima,

W.L. Prado Da Silva,

A. Santoro,

A. Sznajder,

E.J. Tonelli Manganote

7

,

A. Vilela Pereira

UniversidadedoEstadodoRiodeJaneiro,RiodeJaneiro,Brazil

S. Ahuja

a

,

C.A. Bernardes

b

,

A. De Souza Santos

b

,

S. Dogra

a

,

T.R. Fernandez Perez Tomei

a

,

E.M. Gregores

b

,

P.G. Mercadante

b

,

C.S. Moon

a

,

8

,

S.F. Novaes

a

,

Sandra S. Padula

a

,

D. Romero Abad,

J.C. Ruiz Vargas

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

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,

R. Plestina

9

,

F. Romeo,

S.M. Shaheen,

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,

W. Zou

StateKeyLaboratoryofNuclearPhysicsandTechnology,PekingUniversity,Beijing,China

C. Avila,

A. Cabrera,

L.F. Chaparro Sierra,

C. Florez,

J.P. Gomez,

B. Gomez Moreno,

J.C. Sanabria

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

M. Bodlak,

M. Finger

10

,

M. Finger Jr.

10

CharlesUniversity,Prague,CzechRepublic

M. El Sawy

11

,

12

,

E. El-khateeb

13

,

T. Elkafrawy

13

,

A. Mohamed

14

,

A. Radi

12

,

13

,

E. Salama

12

,

13

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,

T. Jarvinen,

V. Karimäki,

R. Kinnunen,

T. Lampén,

K. Lassila-Perini,

S. Lehti,

T. Lindén,

P. Luukka,

T. Mäenpää,

T. Peltola,

E. Tuominen,

J. Tuominiemi,

E. Tuovinen,

L. Wendland

HelsinkiInstituteofPhysics,Helsinki,Finland

J. Talvitie,

T. Tuuva

LappeenrantaUniversityofTechnology,Lappeenranta,Finland

M. Besancon,

F. Couderc,

M. Dejardin,

D. Denegri,

B. Fabbro,

J.L. Faure,

C. Favaro,

F. Ferri,

S. Ganjour,

A. Givernaud,

P. Gras,

G. Hamel de Monchenault,

P. Jarry,

E. Locci,

M. Machet,

J. Malcles,

J. Rander,

A. Rosowsky,

M. Titov,

A. Zghiche

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

I. Antropov,

S. Baffioni,

F. Beaudette,

P. Busson,

L. Cadamuro,

E. Chapon,

C. Charlot,

T. Dahms,

O. Davignon,

N. Filipovic,

A. Florent,

R. Granier de Cassagnac,

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. Agram

15

,

J. Andrea,

A. Aubin,

D. Bloch,

J.-M. Brom,

M. Buttignol,

E.C. Chabert,

N. Chanon,

C. Collard,

E. Conte

15

,

X. Coubez,

J.-C. Fontaine

15

,

D. Gelé,

U. Goerlach,

C. Goetzmann,

A.-C. Le Bihan,

J.A. Merlin

2

,

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,

H. Xiao

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

T. Toriashvili

16

GeorgianTechnicalUniversity,Tbilisi,Georgia

Z. Tsamalaidze

10