Measurement of the ratio B(B[0,s] to J/psi f0(980)) / B(B[0,s] to J/psi phi(1020)) in pp collisions at sqrt(s) = 7 TeV

0.38 MB·English

by  CMS Collaboration

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-PH-EP/2013-037
2016/03/15
CMS-BPH-14-002
Measurement of the ratio
B(B0 → J/ψ f (980))/B(B0 → J/ψ φ(1020)) in pp collisions
s 0 √s
at s = 7TeV
6
1
0
2
The CMS Collaboration∗
r
a
M

4
1

] Abstract
x
e
-
p A measurement of the ratio of the branching fractions of the B0 meson to J/ψf (980)
s 0
e
and to J/ψφ(1020) is presented. The J/ψ, f (980), and φ(1020) are observed through
h 0
[ theirdecaystoµ+µ−, π+π−,andK+K−,respectively. Thef0 andtheφareidentified

2 byrequiring|Mπ+π− −974MeV| < 50MeVand|MK+K− −1020MeV| < 10MeV. The
v analysisisbasedonadatasampleofppcollisionsatacentre-of-massenergyof7TeV,
9 collected by the CMS experiment at the LHC, corresponding to an integrated lumi-
8
0 nosityof5.3fb−1. Themeasuredratiois B(B0s→J/ψf0)B(f0→π+π−) = 0.140±0.008(stat)±
B(B0→J/ψφ)B(φ→K+K−)
6 s
0.023(syst),wherethefirstuncertaintyisstatisticalandthesecondissystematic.
0
.
1
0
5 PublishedinPhysicsLettersBasdoi:10.1016/j.physletb.2016.02.047.
1
:
v
i
X
r
a
(cid:13)c 2016CERNforthebenefitoftheCMSCollaboration.CC-BY-3.0license
∗SeeAppendixAforthelistofcollaborationmembers

1
1 Introduction
SincetheobservationofthedecayB0 → J/ψπ+π−withJ/ψ → µ+µ−,andtheπ+π−massspec-
s
trumindicatingalargef (980)component[1],thischannelhasbeenregardedwithgreatinter-
0
estinheavy-flavorphysics. Moredetailedstudiesoftheπ+π− massspectrumhaveshownthe
π+π− systemtobealmostentirelyCPodd[2,3]. Thisopensupthepossibilityofdirectlymea-
suring the lifetime of the CP-odd part of the B0 meson [4, 5]. In addition, the B0 → J/ψπ+π−
s s
decay has been used for the measurement of the CP-violating phase φ [6, 7], making an im-
s
portant contribution to the world-average value of φ [8–13]. The phase φ is predicted to be
s s
smallinthestandardmodel[14],makingitsdeterminationinterestingbecauseofthelargeen-
hancements that can be introduced by new physics [15, 16]. In what follows, we will refer to
thef (980)asf andtheφ(1020)asφ.
0 0
This Letter presents the measurement of the ratio R of the branching fractions B(B0 →
f0/φ s
J/ψf )B(f → π+π−)andB(B0 → J/ψφ)B(φ → K+K−),whereinbothcasestheJ/ψisdetected
0 0 s
throughitsdecayto µ+µ−. Thef0 andthe φ areidentifiedbyrequiring |Mπ+π− −974MeV| <
50MeV and |MK+K− −1020MeV| < 10MeV. The appearance of B0s → J/ψf0 decays was first
discussedin[17]withatheoreticalestimatefor R ofapproximately0.2,whichisconsistent
f0/φ
with results from several experiments [2, 4, 18, 19]. Detailed studies of the π+π− mass spec-
trumoftheB0s → J/ψπ+π−decayin0.3 < Mπ+π− < 2.5GeV[2,3]revealthisfinalstatetohave
contributionsfromseveralresonancesin Mπ+π−,andthef0 componenttorangefrom65.0%to
94.5%. However, according to the same results, the contaminations from other resonances in
|Mπ+π− −974MeV| < 50MeV are several orders of magnitude lower than the f0 component,
including the non-resonant S-wave. Based on this, the measurement of R is performed as-
f0/φ
suming that the selected region of Mπ+π− is dominated by B0s → J/ψf0 decays and neglecting
otherresonances. Systematicuncertaintiesareassignedtothemeasurementowingtotheseas-
sumptions,takingintoaccounttheuncertaintyinthef componentandtheinterferenceswith
0
otherresonancesintheselectedmasswindowfor Mπ+π−.
Experimentally,theratio R isgivenby
f0/φ
B(B0 → J/ψf )B(f → π+π−) Nf0
R = s 0 0 = obs (cid:101)φ/f0, (1)
f0/φ B(B0s → J/ψφ)B(φ → K+K−) Nφ reco
obs
where Nf0 and Nφ are the observed yields of B0 → J/ψ(µ+µ−)f with f → π+π− and
obs obs s 0 0
B0 → J/ψ(µ+µ−)φ with φ → K+K− decays, respectively, and (cid:101)φ/f0 is the ratio of the detection
s reco
efficiencies for the B0 decay mode with a φ to the decay mode with a f . Uncertainties in
s 0
the b quark production cross section cancel in the ratio, as do those from the J/ψ → µ+µ−
branchingfractionandtheintegratedluminosity. Giventhesimilartopologiesofthetwofinal
states, systematic uncertainties related to the tracking efficiency and the muon identification
alsocancelintheratio.
2 The CMS detector
The central feature of the CMS apparatus is a superconducting solenoid of 6m internal diam-
eter. Within the 3.8T field volume are a silicon pixel and strip tracker, a lead tungstate crystal
electromagneticcalorimeter,andabrassandscintillatorhadroncalorimeter,eachcomposedof
abarrelandtwoendcapsections. Muonsaremeasuredinthepseudorapidityrange|η| < 2.4in
gas-ionizationdetectorsembeddedinthesteelflux-returnyokeoutsidethesolenoid,whichare
made using three technologies: drift tubes, cathode strip chambers, and resistive-plate cham-
2 3 Eventselection
bers. Extensive forward calorimetry complements the coverage provided by the barrel and
endcap detectors. The main subdetectors used in this analysis are the silicon tracker and the
muonsystems.
The silicon tracker measures charged particles within the pseudorapidity range |η| < 2.5 and
consists of 1440 silicon pixel and 15148 silicon strip detector modules. Matching muons to
tracksmeasuredinthesilicontrackerresultsinarelativetransversemomentumresolutionfor
muons with 20 < p < 100GeV of 1.3–2.0% in the barrel and better than 6% in the endcaps,
T
The p resolutioninthebarrelisbetterthan10%formuonswith p upto1TeV[20].
T T
ThefirstleveloftheCMStriggersystem,composedofcustomhardwareprocessors,usesinfor-
mationfromthecalorimetersandmuondetectorstoselectthemostinterestingeventsinafixed
time interval of less than 4µs. The high-level trigger (HLT) processor farm further decreases
theeventratetolessthan1kHz,beforedatastorage.
A more detailed description of the CMS detector, together with a definition of the coordinate
systemusedandtherelevantkinematicvariables,canbefoundinRef. [21].
3 Event selection
The data sample used for this measurement was collected in 2011 by the CMS experiment at
theCERNLHCinproton-protoncollisionsatacentre-of-massenergyof7TeVandcorresponds
toanintegratedluminosityof5.3fb−1.
The search for B0 → J/ψf decays is performed in events with two muon candidates selected
s 0
bythedimuontriggerattheHLT,requiringthemuonpairtooriginatefromadisplacedvertex.
The dimuon candidates are further required to comply with L /σ > 3, where L is the
xy xy xy
(cid:126)
magnitudeofthevectorL ,whichliesinaplanetransversetothebeamaxisandpointsfrom
xy
theinteractionpointtothedimuonvertex,and σ isitsuncertainty;cosα > 0.9,where α
xy J/ψ J/ψ
is the angle between the direction of the dimuon transverse momentum and(cid:126)L ; p > 4GeV
xy T
and |η| < 2.2 for each muon candidate; p > 7GeV for the dimuon; the distance of closest
T
approachofeachmuontrackwithrespecttotheothermuontrack<0.5cm.
ReconstructionoftheB0 → J/ψf decaysbeginswiththesearchforJ/ψcandidatesbycombin-
s 0
ingtwomuonsofoppositechargetoformavertexwithafitprobability>0.5%andaninvariant
mass (M ) within |M −3097.6MeV| < 150MeV. To search for f candidates, two tracks of
J/ψ J/ψ 0
oppositechargeassumedtobepionsareconstrainedtoavertexwithaprobability >5%. One
pioncandidatemusthave p > 1GeVandtheother p > 2.5GeV. Inaddition,thef candidate
T T 0
must have p > 3.5GeV and M in the range |M −974MeV| < 50MeV. The 974MeV is the
T f0 f0
measured mass of f signal in data modeled by a Breit–Wigner function. This value is consis-
0
tentwiththef massfromtheParticleDataGroup[22]andtheLHCbmeasurement[1]. Finally,
0
a vertex is formed with the J/ψ and f candidates, constraining the dimuon mass to the nomi-
0
nalJ/ψ mass[22]. TheB0 → J/ψf candidatesarerequiredtohaveavertexprobability >10%,
s 0
p > 13GeV,cosα > 0.994,whereα istheanglebetweenthedirectionoftheB0 transverse
T B0 B0 s
s s
momentumandthevector(cid:126)L , andaproperdecaylength >100µm. Theproperdecaylength
xy
is defined as ((cid:126)L ·(cid:126)p M /p2), where(cid:126)p is the transverse momentum ofthe B0 candidate and
xy T B T T s
M istheworld-averageB0 mass[22]. InthecaseofmultipleB0 candidatesperevent,theone
B s s
with smallest B0s vertex fi√t χ2 is selected. The selection criteria for the B0s candidates are estab-
lishedbymaximizing S/ S+B,where S isthesignalyieldobtainedfromMonteCarlo(MC)
simulationand Bisthebackgroundyieldtakenfromsidebandregions,definedasthenumber
ofeventswithaµ+µ−π+π− invariantmassintherange5.27to5.30GeVor5.43to5.46GeV.
3
Thesameprocedureandselectioncriteriaareappliedtothereconstructionofthenormalization
channelB0 → J/ψφ,exceptthattheinvariantmassrequirement|M −1020MeV| < 10MeVis
s φ
tighterthanthatforthef .
0
4 Results
The signal yields of both decay channels are extracted using unbinned maximum-likelihood
fitsofthemassdistributions. TheinvariantmassdistributionoftheJ/ψ(µ+µ−)f (π+π−) can-
0
didates is shown in Fig. 1. It is fit with a superposition of a Gaussian function representing
the signal, a polynomial function to account for the combinatorial background, and another
Gaussianfunctionforanypossiblepeakingbackground. Thelattermodelsresonantstructures
that could appear in the left sideband of the J/ψ(µ+µ−)f (π+π−) signal mass owing to the
0
misidentification of a kaon as a pion coming from decays such as B0 → J/ψK∗(892)(K+π−)
and B0 → J/ψK+K−, as examples. In addition, B+ → J/ψK+(π+) decays can be a source of
s
backgroundwhencombinedwithanextrabackgroundpioncandidate. Whenallowingallpa-
rameterstofloat,thefitreturnsNf0 = 873±49eventsandaB0massof5369.1±0.9MeV,with
obs s
aresolutionof15.9±0.9MeV,wheretheuncertaintiesarestatisticalonly. Themeasuredvalues
oftheB0 massanditsresolutionareconsistentwiththeMCsimulation.
s
5.3 fb-1 (7 TeV)
350
V
e CMS
M Data
9 300 Fit
nts / 250 Signal
e
v Combinatorial background
E200
Peaking background
150
100
50
0
5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5 5.55
Pull 2 J/y p p Invariant mass [GeV]
0
-2
5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5 5.55
J/y p +p - invariant mass [GeV]
Figure 1: Invariant mass distribution of the B0 → J/ψ(µ+µ−)f (π+π−) candidates (filled cir-
s 0
cles). ThesignalismodelledasaGaussian(dot-dashedline),thecombinatorialbackgroundas
afirst-orderpolynomialfunction(dashed-double-dottedline),andthepeakingbackgroundby
aGaussian(dottedline). Theresultofthetotalfitisshownwiththesolidline. Thebottomplot
showsthepull,whichisthedeviationofthedatafromthefitdividedbytheuncertaintyinthe
data.
The J/ψ(µ+µ−)φ(K+K−) invariant mass distribution is modelled by two Gaussian functions
for the signal and a constant function for the combinatorial background. A signal yield of
Nφ = 8377±107 events is obtained, with a B0 mass of 5366.8±0.2MeV and a resolution
obs s
of 17.1±0.1MeV, which are consistent with the MC simulation. The corresponding invariant
4 4 Results
massdistributionispresentedinFig. 2.
5.3 fb-1 (7 TeV)
V
Me1000 CMS
5 Data
4.
s / 800 Fit
nt Signal
e
v 600 Combinatorial background
E
400
200
0
5.25 5.3 5.35 5.4 5.45
ull 2 J/y KK mass [GeV]
P
0
-2
-4
5.25 5.3 5.35 5.4 5.45
J/y K+K- invariant mass [GeV]
Figure2: InvariantmassdistributionoftheB0 → J/ψ(µ+µ−)φ(K+K−)candidates(blackfilled
s
circles). The signal model is a double Gaussian (dot-dashed line), while the combinatorial
backgroundmodelisaconstantfunction(dash-double-dottedline). Thetotalfitisrepresented
by the solid line. The bottom plot shows the deviation of the data to the fit divided by the
statisticaluncertaintyinthedata.
Using the MC simulation, the detection efficiencies for the two processes are calculated as the
ratio of the reconstructed and generated yields. The B0 meson production is simulated using
s
PYTHIA 6.4.24 [23] and its decays simulated with EVTGEN [24]. The B0 mass and lifetime are
s
set to 5369.6MeV and 438µm in the simulation. The decay model used for the B0 → J/ψf
s 0
decay is a phase-space model reweighted to reflect the spin-1 structure of the J/ψ → µ+µ−
decay. The corresponding models for the B0 → J/ψφ decay are: a pseudoscalar-vector-vector
s
with CP violation [25, 26] for the B0 decay, with parameters [24] ||A ||2 = 0.24, ||A ||2 = 0.6,
s || 0
||A ||2 = 0.16,φ = 2.5,φ = 0,andφ = −0.17;avector-lepton-leptonmodelwithradiation
⊥ || 0 ⊥
(PHOTOS) [27] for the J/ψ → µ+µ− decay; and a vector-scalar-scalar model [24] for the φ →
K+K− decay. Theeventsareprocessedwitha GEANT4-baseddetectorsimulation[28]andthe
samereconstructionalgorithmsusedondata. InordertovalidatetheMCsimulationsamples,
relevant kinematic and geometric variables of both simulated decay channels are compared
withthedataafterbackgroundsubtractionandfoundtobeinagreement. Forexample,Fig. 3
comparesthe p andinvariantmassdistributionsofthef (π+π−)candidatesforbackground-
T 0
subtracted data and MC simulation. The f width was set to 50MeV in the MC simulation.
0
This is consistent with what is observed in our data as shown in the Fig. 3.b. The ratio of the
detectionefficienciesforthetwoB0 decaysiscalculatedtobe (cid:101)φ/f0 = 1.344±0.095, wherethe
s reco
uncertainty reflects the limited size of simuated samples. Using the corresponding values of
Nf0 , Nφ , and (cid:101)φ/f0 in Eq. (1), we measure R = 0.140±0.008, where the uncertainty is
obs obs reco f0/φ
statisticalonly.
Thestabilityofthe R measurementisverifiedwithcontrolchecksusingdifferentrunperi-
f0/φ
ods, selection criteria, and geometric acceptances. To study possible effects from varying run
5
5.3 fb-1 (7 TeV) 5.3 fb-1 (7 TeV)
V V
Ge 0.4 CMS Data a) Me 0.18 CMS Data b)
2 1
vents / 00.3.35 MC ents / 100..1146 MC
e v
ber of 0.25 er of e 0.01.21
um 0.2 mb
n u 0.08
ed 0.15 d n
z e 0.06
mali 0.1 aliz
Nor orm0.04
0.05 N 0.02
0 0
4 6 8 10 12 14 16 18 0.85 0.9 0.95 1 1.05 1.1
p of p +p - [GeV] p +p - invariant mass [GeV]
T
Figure 3: Comparison of normalized MC simulation (triangles) and background-subtracted
data(squared)for(a)the p and(b)invariantmassdistributionsofthef (π+π−)candidates.
T 0
conditions, the value of R is determined for two subsamples, found by dividing the data
f0/φ
into two. The ratio is also measured after changing the selection criteria for the proper decay
length and p of the B0 candidates and the p of the leading and subleading pion candidates,
T s T
andbyusingdifferentazimuthalangleandηrequirementsforthemuons. Noneofthesecross-
checksrevealedanystatisticallysignificantbias.
5 Systematic uncertainties
PotentialsystematicuncertaintiesinthemeasurementofR comefromsourcessuchastheB0
f0/φ s
signalyieldextractionprocedure,therelativeefficiencyestimation,andpossiblecontributions
totheB0 yieldsfromotherdecaysproducingtheJ/ψπ+π− andJ/ψK+K− finalstates.
s
Systematicuncertaintiesinthesignalyieldextractionareestimatedbychangingthemodeling
ofthesignalandthebackgroundinvariantmassdistributionsinthelikelihoodfits. Forthecase
oftheB0 → J/ψf massdistributionthesignalshapeischangedtoadouble-Gaussianfunction
s 0
and the background to an exponential function, while for the B0 → J/ψφ mass distribution
s
the signal is changed to a Gaussian function and its background is modelled as a first-order
polynomialfunction. Thesechangesleadtoamaximumvariationof2.1%in R .
f0/φ
Thereareseveralfactorsthatmayaffecttheestimateof(cid:101)φ/f0. WhiletheMCsimulationpackage
reco
uses a Breit–Wigner model to simulate the f → π+π− process, it has been pointed out [2, 3]
0
thataFlatte´ modelisabetterdescriptionofthisdecay. Toestimatetheeffectofthesimulation
model, the Breit–Wigner model used in the simulation is compared to a Flatte´ model in the
selected Mπ+π− region. Thedifferenceinthemodelsreflectsasystematicerrorof5.8%in(cid:101)rφe/cfo0.
This is quoted as a systematic uncertainty. In addition, in the MC simulation the f width is
0
set to 50MeV. This value is varied by ±10MeV, resulting in a systematic uncertainty of 8.6%
in R . The models used in the MC simulation of the B decays are set to phase-space [24]
f0/φ s
insteadofthedefaultdecaymodels,leadingtoa6.2%systematicuncertaintyin R . Finally,
f0/φ
thestatisticaluncertaintyin(cid:101)φ/f0 owingtothefinitenumberofMCevents,whichcorresponds
reco
to7.1%,isaddedasasystematicuncertainty.
As mentioned in the introduction, detailed studies of the π+π− mass spectrum of the B0 →
s
J/ψπ+π− decay[2,3]inamasswindowof0.3–2.5GeV,revealthisfinalstatetohavecontribu-
6 6 Summary
tions from several resonances in Mπ+π−, and the f0 component to range from 65.0 to 94.5% in
the entire mass window studied by LHCb. To study the effects of the interferences and the f
0
fraction observed by LHCb in the estimate of (cid:101)φ/f0, the model reported in [3] for the lowest f
reco 0
fractionandlargestnon-resonantcomponentwascomparedtothesingleBreit–Wignermodel
used in the MC simulation of the f0 → π+π decay. The comparison in the selected Mπ+π− re-
gionshowsavariationof5.6%inR . Thisisquotedasasystematicuncertaintycomingfrom
f0/φ
this source. It can be observed in the same LHCb study that the contaminations from other
resonances in the mass region |Mπ+π− −974MeV| < 50MeV are several orders of magnitude
lowerthanthef component, includingthenon-resonantS-wave. Toestimatethevariationin
0
the B0 yield coming from these possible contributions, the f mass window is widened from
s 0
50 to 100MeV around the f mass, resulting in a variation in R of 6.4% that is quoted as a
0 f0/φ
systematicuncertainty. FortheB0 → J/ψK+K− decaychannel, thecontributionoftheS-wave
s
inaφmasswindowsimilartowhatisusedinthisanalysishasbeenfoundtobenegligible[29].
Combiningtheseuncertaintiesinquadratureleadstoatotalsystematicuncertaintyof16.5%.
6 Summary
√
UsingdatacollectedbytheCMSexperimentinproton-protoncollisionsat s = 7TeV,corres-
pondingtoanintegratedluminosityof5.3fb−1,873±49eventsofB0 → J/ψ(µ+µ−)f (π+π−)
s 0
and 8377±107 events of B0 → J/ψ(µ+µ−)φ(K+K−) are observed. The f and φ are identi-
s 0
fied in the mass ranges |Mπ+π− −974MeV| < 50MeV and |MK+K− −1020MeV| < 10MeV,
respectively. TheratioofthebranchingfractionofB0 → J/ψ(µ+µ−)f (π+π−)tothebranching
s 0
fractionofB0 → J/ψ(µ+µ−)φ(K+K−), R ,isfoundtobe
s f0/φ
B(B0 → J/ψf )B(f → π+π−)
s 0 0 = 0.140±0.008(stat)±0.023(syst). (2)
B(B0 → J/ψφ)B(φ → K+K−)
s
This result is consistent with the theoretical prediction of about 0.2 [17] and with previous
measurementsindifferentrangesof Mπ+π− [2,4,19].
Acknowledgments
We congratulate our colleagues in the CERN accelerator departments for the excellent perfor-
manceoftheLHCandthankthetechnicalandadministrativestaffsatCERNandatotherCMS
institutes for their contributions to the success of the CMS effort. In addition, we gratefully
acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid
fordeliveringsoeffectivelythecomputinginfrastructureessentialtoouranalyses. Finally,we
acknowledgetheenduringsupportfortheconstructionandoperationoftheLHCandtheCMS
detectorprovidedbythefollowingfundingagencies: BMWFWandFWF(Austria);FNRSand
FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS,
MoST,andNSFC(China);COLCIENCIAS(Colombia);MSESandCSF(Croatia);RPF(Cyprus);
MoER,ERCIUTandERDF(Estonia);AcademyofFinland,MEC,andHIP(Finland);CEAand
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 (Re-
public of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP,
and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland);
FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia);
SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter,
References 7
IPST,STARandNSTDA(Thailand);TUBITAKandTAEK(Turkey);NASUandSFFR(Ukraine);
STFC(UnitedKingdom);DOEandNSF(USA).
Individuals have received support from the Marie-Curie programme and the European Re-
search Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan
Foundation; theAlexandervonHumboldtFoundation; theBelgianFederalSciencePolicyOf-
fice; the Fonds pour la Formation a` la Recherche dans l’Industrie et dans l’Agriculture (FRIA-
Belgium);theAgentschapvoorInnovatiedoorWetenschapenTechnologie(IWT-Belgium);the
Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Sci-
enceandIndustrialResearch,India;theHOMINGPLUSprogrammeofFoundationforPolish
Science, cofinanced from European Union, Regional Development Fund; the Compagnia di
SanPaolo(Torino);theConsorzioperlaFisica(Trieste);MIURproject20108T4XTM(Italy);the
ThalisandAristeiaprogrammescofinancedbyEU-ESFandtheGreekNSRF;andtheNational
PrioritiesResearchProgrambyQatarNationalResearchFund.
References
[1] LHCbCollaboration,“FirstobservationofB0 → J/ψf (980)decays”, Phys.Lett.B 698
s 0
(2011)115,doi:10.1016/j.physletb.2011.03.006,arXiv:1102.0206.
[2] LHCbCollaboration,“AnalysisoftheresonantcomponentsinB0 → J/ψπ+π−”, Phys.
s
Rev.D 86(2012)052006,doi:10.1103/PhysRevD.86.052006,arXiv:1204.5643.
[3] LHCbCollaboration,“MeasurementoftheresonantandCPcomponentsin
B0 → J/ψπ+π− decays”, Phys.Rev.D 89(2014)092006,
s
doi:10.1103/PhysRevD.89.092006,arXiv:1402.6248.
[4] CDFCollaboration,“MeasurementofbranchingratioandB0 lifetimeinthedecay
s
B0 → J/ψf (980)atCDF”, Phys.Rev.D 84(2011)052012,
s 0
doi:10.1103/PhysRevD.84.052012,arXiv:1106.3682.
[5] LHCbCollaboration,“MeasurementoftheB0 effectivelifetimeintheJ/ψf (980)final
s 0
state”, Phys.Rev.Lett. 109(2012)152002,doi:10.1103/PhysRevLett.109.152002,
arXiv:1207.0878.
0
[6] LHCbCollaboration,“MeasurementoftheCP-violatingphaseφ inB → J/ψf (980)”,
s s 0
Phys.Lett.B 707(2012)497,doi:10.1016/j.physletb.2012.01.017,
arXiv:1112.3056.
[7] LHCbCollaboration,“MeasurementoftheCP-violatingphaseφ inB0 → J/ψπ+π−
s s
decays”, Phys.Lett.B 736(2014)186,doi:10.1016/j.physletb.2014.06.079,
arXiv:1405.4140.
[8] D0Collaboration,“MeasurementofB0 mixingparametersfromtheflavor-taggeddecay
s
B0 → J/ψφ”, Phys.Rev.Lett. 101(2008)241801,
s
doi:10.1103/PhysRevLett.101.241801,arXiv:0802.2255.
[9] CDFCollaboration,“Firstflavor-taggeddeterminationofboundsonmixing-inducedCP
violationinB0 → J/ψφdecays”, Phys.Rev.Lett. 100(2008)161802,
s
doi:10.1103/PhysRevLett.100.161802,arXiv:0712.2397.
8 References
J/ψφ
[10] D0Collaboration,“MeasurementoftheCP-violatingphaseφ usingtheflavor-tagged
s
decayB0 → J/ψφin8fb−1 ofppcollisions”, Phys.Rev.D. 85(2012)032006,
s
doi:10.1103/PhysRevD.85.032006,arXiv:1109.3166.
[11] LHCbCollaboration,“MeasurementoftheCP-violatingphaseφ inthedecay
s
B0 → J/ψφ”, Phys.Rev.Lett. 108(2012)101803,
s
doi:10.1103/PhysRevLett.108.101803,arXiv:1112.3183.
[12] ATLASCollaboration,“Time-dependentangularanalysisofthedecayB0 → J/ψφand
s
extractionof∆Γ andtheCP-violatingweakphaseφ byATLAS”, JHEP 12(2012)072,
s s
doi:10.1007/JHEP12(2012)072,arXiv:1208.0572.
[13] CMSCollaboration,“MeasurementoftheCP-violatingweakphaseφ andthedecay
s
widthdifference∆Γ usingtheB0 → J/ψφ(1020)decaychannelinppcollisionsat
√ s s
s = 8TeV”,(2015).arXiv:1507.07527.SubmittedtoPhys.Lett.B.
[14] J.Charlesetal.,“Predictionsofselectedflavourobservableswithinthestandardmodel”,
Phys.Rev.D 84(2011)033005,doi:10.1103/PhysRevD.84.033005,
arXiv:1106.4041.
[15] P.BallandR.Fleischer,“ProbingnewphysicsthroughBmixing: status,benchmarksand
prospects”, Eur.Phys.J.C 48(2006)413,doi:10.1140/epjc/s10052-006-0034-4,
arXiv:hep-ph/0604249.
[16] A.Lenz,“UnparticlephysicseffectsinB -B mixing”, Phys.Rev.D 76(2007)065006,
s s
doi:10.1103/PhysRevD.76.065006,arXiv:0707.1535.
[17] S.StoneandL.Zhang,“S-wavesandthemeasurementofCP-violatingphasesinB
s
decays”, Phys.Rev.D 79(2009)074024,doi:10.1103/PhysRevD.79.074024,
arXiv:0812.2832.
[18] BELLECollaboration,“ObservationofB0 → J/ψf (980)andevidencefor
s 0
B0 → J/ψf (1370)”, Phys.Rev.Lett 106(2011)121802,
s 0
doi:10.1103/PhysRevLett.106.121802,arXiv:1102.2759.
[19] D0Collaboration,“MeasurementoftherelativebranchingratioofB0 → J/ψf (980)to
s 0
B0 → J/ψφ”, Phys.Rev.D 85(2012)011103,doi:10.1103/PhysRevD.85.011103,
s
arXiv:1110.4272.
[20] CMSCollaboration,“PerformanceofCMSmuonreconstructioninppcollisioneventsat
√
s = 7TeV”, JINST 7(2012)P10002,doi:10.1088/1748-0221/7/10/P10002,
arXiv:1206.4071.
[21] CMSCollaboration,“TheCMSexperimentattheCERNLHC”, JINST 03(2008)S08004,
doi:10.1088/1748-0221/3/08/S08004.
[22] ParticleDataGroup,J.Beringeretal.,“ReviewofParticlePhysics”, Phys.Rev.D 86
(2012)010001,doi:10.1103/PhysRevD.86.010001.
[23] T.Sjo¨strand,S.Mrenna,andP.Skands,“PYTHIA6.4physicsandmanual”, JHEP 05
(2006)026,doi:10.1088/1126-6708/2006/05/026,arXiv:hep-ph/0603175.
[24] D.Lange,“TheEvtGenparticledecaysimulationpackage”, Nucl.Instrum.Meth.A 462
(2001)152,doi:10.1016/S0168-9002(01)00089-4.