Measurement of the CP-violating phase βin B0→J/ψπ+π−decays and limits on penguin effects

Physics Letters B 742 (2015) 38–49 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Measurement of the CP-violating phase βin B0→J/ψπ+π−decays and limits on penguin effects .LHCb Collaboration a r t i c l e i n f o a b s t r a c t Article history: Received 6 November 2014 Received in revised form 23 December 2014 Accepted 7 January 2015 Available online 13 January 2015 Editor: W.-D. Schlatter Time-dependent CP violation is measured in the (—) B0→J/ψπ+π−channel for each π+π−resonant final state using data collected with an integrated luminosity of 3.0 fb−1in pp collisions using the LHCb detector. The final state with the largest rate, J/ψρ0(770), is used to measure the CP-violating angle 2βeff to be (41.7 ±9.6+2.8 −6.3)◦.This result can be used to limit the size of penguin amplitude contributions to CP violation measurements in, for example, (—) B0 s→J/ψφ decays. Assuming approximate SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the CP-violating phase φsis limited to be within the interval [−1.05◦, +1.18◦] at 95% confidence level. Changes to the limit due to SU(3) symmetry breaking effects are also discussed. ©2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3. 1. Introduction Measurements of CP violation in neutral Bmeson decays are used either to search for physics beyond the Standard Model (SM) [1] or set limits on combinations of Cabibbo–Kobayashi–Maskawa couplings (Vij)[2]. Interpretations of the measurement of the CP-violating phase 2βvia the interference of mixing and decays in the (—) B0→J/ψ K0 Schannel, and the phase φsin (—) B0 s→J/ψφ and J/ψπ+π−decays,1are made assuming that the decays are dominated by tree-level processes. However, penguin processes are also possible, and they may have amplitudes large enough to influence the results. Here we use (—) B0→J/ψπ+π−decays to set limits on possible changes due to penguin contributions. This mode has both tree and penguin diagrams, as shown in Fig. 1. Theoretical models, to be discussed later, predict that the ratio of penguin to tree amplitudes is greatly enhanced in this decay relative to (—) B0→J/ψ K0 S[3,4]. Thus, the effects of penguin topologies can be investigated by using the J/ψπ+π−decay and comparing differ1CP violation measurements in (—) B0→J/ψ K0 Sdetermine the sum of 2β≡ 2 arg(−Vcd V∗ cb)/(Vtd V∗ tb)and contributions from higher order diagrams. Similar measurements in the (—) B0 ssystem determine φswhich is the sum of −2βs≡ −2 arg(−VtsV∗ tb)/(Vcs V∗ cb)and higher order corrections. Fig. 1. (a) Tree level and (b) penguin diagram for B0decays into J/ψπ+π−. ent measurements of the CP-violating phase 2βin J/ψ K0 S, and individual channels such as (—) B0→J/ψρ0(770).2 Next, we discuss the time-dependent decay rate, taking into account that the π+π−system is composed of the resonances previously reported in Ref. [5].This analysis largely follows the measurement procedure used in the study of CP violation in (—) B0 sdecays into J/ψπ+π−[6]. The total decay amplitude for (—) B0at a decay time of zero is taken to be the sum over individual π+π−resonant transversity amplitudes [7], and possibly one non-resonant amplitude, with each component labeled as Ai(Ai). The quantities qand prelate the mass eigenstates to the flavor eigenstates [8]. By introducing the parameter λi≡q p Ai Ai, relating CP violation in the interference between mixing and decay associated with the state i, the amplitudes Aand Acan be expressed as the sums of the individual (—) B0amplitudes, A =Aiand A=q pAi=λiAi= 2In the following ρ0or ρrefers to the ρ0(770)meson. http://dx.doi.org/10.1016/j.physletb.2015.01.008 0370-2693/©2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3. LHCb Collaboration / Physics Letters B 742 (2015) 38–49 39 ηi|λi|e−i2βeff iAi. For each transversity state ithe CP-violating phase 2βeff i≡− arg(ηiλi)with ηibeing the CP eigenvalue of the state.3The decay rates are4 Γ(t)=Ne−Γdt|A|2+|A|2 2+|A|2−|A|2 2cos(mdt) −ImA∗Asin(mdt), Γ(t)=Ne−Γdt|A|2+|A|2 2−|A|2−|A|2 2cos(mdt) +ImA∗Asin(mdt).(1) 2. Penguin and tree amplitudes The decay B0→J/ψ K0 Scan be written as the sum of one tree level amplitude, similar to that shown in Fig. 1(a), but where the virtual W−transforms to a cs pair, and three penguin amplitudes similar to those shown in Fig. 1(b). Here we neglect higher order diagrams. The t-quark mediated penguin amplitude can be expressed in terms of the other two using CKM unitarity. The resulting decay amplitude is [3] A(B0→J/ψ K0 S)=1− λ2 2A1+ λ2 1− λ2aeiθeiγ,(2) where  λ=|Vus| =0.2252 [10], γ≡arg(−VudV∗ ub/Vcd V∗ cb), Adenotes the sum of tree and penguin strong amplitudes, and aand θare the magnitude and phase of the strong parts of the effective penguin amplitude relative to the tree amplitude. For the case of (—) B0→J/ψπ+π−decays, the π+π−pairs are in spin states ranging from zero to two. Since they are in a final state with a spin-1 J/ψ resonance, the amplitudes in the different transversity states fneed to be distinguished for all spins above zero. For example, the amplitude for each J/ψρ0(770)transversity state is −√2AB0→(J/ψρ)f= λA1−afeiθfeiγ,(3) where the primed quantities are defined in analogy with the unprimed ones in Eq. (2). For B0decays only the sign in front of iγchanges. We are only concerned here with the relative size of the tree and penguin amplitudes. For J/ψ K0 Sthe penguin is suppressed relative to the tree by an additional factor of ≡ λ2/(1− λ2) =0.0534. Thus, comparing even a relatively poor measurement of 2βeff measured in J/ψρ0with 2βmeasured in J/ψ K0 Sallows us to set stringent limits on the penguin contribution. Using approximate SU(3) flavor symmetry the size of the penguin contribution in (—) B0→J/ψρ0can be related to that in (—) B0 s→J/ψφ decays as pointed out in Refs. [4,11]. We now turn to the expressions for CP violation in the presence of both tree and penguin amplitudes. The complex-valued CP parameter λfis given by λf≡q p A(B0→(J/ψρ)f) A(B0→(J/ψρ)f)=ηf 1−afeiθfe−iγ 1−afeiθfeiγe−2iβ,(4) where βis the phase induced by mixing. Thus the measured phase βeff fis related to βby 3Note that while q/pand Ai/Aiare phase convention dependent, λiis not. 4We assume Γd=0and |p/q| =1. The averages of current measurements are Γd/Γd=0.001 ±0.010 and |p/q| =1.0005 ±0.0011 [9]. ηfλf≡|λf|e−i2βeff f=1−afeiθfe−iγ 1−afeiθfeiγe−i2β,(5) separating real and imaginary parts gives |λf|= 1−afeiθfe−iγ 1−afeiθfeiγ,and 2βf≡2βeff f−2β=−arg1−afeiθfe−iγ 1−afeiθfeiγ.(6) For the J/ψ K0 Smode we replace afand θfin Eq. (6) by −af and θf, respectively. In addition, we take a=aand θ=θ. The relationship between the penguin influence on the mixing induced CP violation phase in favored decays and the measurements in (—) B0→(J/ψρ0)fis then given by δP=−arg(λfe2iγ−1)+(λf−1) (λfe2iγ−1)+(λf−1)e2iγ where λf≡|λf|e−i2βf.(7) We will show that the penguin shift has a weak dependence on |λf|, resulting in δP≈−2βf. Since the uncertainty on the current measurement of 2βis (+1.6 −1.5)◦, a measurement of 2βf, even with an uncertainty ten times larger, could limit penguin contributions to be well below the current statistical uncertainty, which is the main aim of this analysis. 3. Detector software and event selection The LHCb detector [12] is a single-arm forward spectrometer covering the pseudorapidity range 2 <η<5, designed for the study of particles containing bor cquarks. The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector surrounding the pp interaction region [13], a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4Tm, and three stations of siliconstrip detectors and straw drift tubes [14] placed downstream of the magnet. The tracking system provides a measurement of momentum,5p, with a relative uncertainty that varies from 0.4% at low momentum to 0.6% at 100 GeV. The minimum distance of a track to a primary vertex (PV), the impact parameter (IP), is measured with a resolution of (15 +29/pT)μm, where pTis the component of ptransverse to the beam, in GeV. Different types of charged hadrons are distinguished using information from two ring-imaging Cherenkov detectors [15]. Photon, electron and hadron candidates are identified by a calorimeter system consisting of scintillating-pad and preshower detectors, an electromagnetic calorimeter and a hadronic calorimeter. Muons are identified by a system composed of alternating layers of iron and multiwire proportional chambers [16]. The trigger [17] consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage that applies a full event reconstruction [17]. Events selected for this analysis are triggered by a J/ψ →μ+μ−decay, where the J/ψ meson is required at the software level to be consistent with coming from the decay of a (—) B0meson by use of either of IP requirements or detachment of the J/ψ meson decay vertex 5We use natural units where ¯ h=c=1. 40 LHCb Collaboration / Physics Letters B 742 (2015) 38–49 from the primary vertex. In the simulation, pp collisions are generated using Pythia [18] with a specific LHCb configuration [19]. Decays of hadronic particles are described by EvtGen [20], in which final state radiation is generated using Photos [21]. The interaction of the generated particles with the detector and its response are implemented using the Geant4 toolkit [22] as described in Ref. [23]. A (—) B0→J/ψπ+π−candidate is reconstructed by combining a J/ψ →μ+μ−candidate with two pions of opposite charge. The like-sign combinations J/ψπ±π±are also reconstructed for background studies. The event selection is described in detail in the time-integrated amplitude analysis [5]. The only difference here is that we reject K0 S→π+π−candidates by excluding the events in the region within ±20 MeV of the K0 Smass peak. Only candidates with dimuon invariant mass between −48 MeV and +43 MeV relative to the observed J/ψ mass peak are selected, corresponding a window of about ±3σ. The two muons subsequently are kinematically constrained to the known J/ψ mass. Other requirements are imposed to isolate B0candidates with high signal yield and minimum background. This is accomplished by combining the J/ψ →μ+μ−candidate with a pair of pion candidates of opposite charge, and then testing if all four tracks form a common decay vertex. Pion candidates are each required to have pTgreater than 250 MeV, and the scalar sum of the two transverse momenta, pT(π+) +pT(π−), must be larger than 900 MeV. To test for inconsistency with production at the PV, the IP χ2is computed as the difference between the χ2of the PV reconstructed with and without the considered track. Each pion must have an IP χ2greater than 9. Pion and kaon candidates are positively identified using the RICH system. The four-track B0candidate must have a flight distance of more than 1.5 mm, where the average decay length resolution is 0.17 mm. The angle between the combined momentum vector of the decay products and the vector formed from the positions of the PV and the decay vertex (pointing angle) is required to be less than 2.5◦. Events satisfying this preselection are then further filtered using a multivariate analyzer based on a Boosted Decision Tree (BDT) technique [24]. The BDT uses eight variables that are chosen to provide separation between signal and background. These are the minimum of DLL(μ −π) of the μ+and μ−, pT(π+) +pT(π−), the minimum of IP χ2of the π+and π−, and the B0properties of vertex χ2, pointing angle, flight distance, pTand IP χ2, where DLL(μ −π) is a logarithm of the likelihood ratio between μand πhypotheses for the muon candidates. The BDT is trained on a simulated sample of two million B0→ J/ψπ+π−signal events generated uniformly in phase space with unpolarized J/ψ →μ+μ−decays, and a background data sample from the sideband 5566 <m(J/ψπ+π−) <5616 MeV. Then separate samples are used to train and test the BDT. The invariant mass of the selected J/ψπ+π−combinations, where the dimuon pair is constrained to have the J/ψ mass, is shown in Fig. 2. There is a large peak at the B0 smass and a smaller one at the B0mass on top of the background. A double Crystal Ball function with common means models the radiative tails and is used to fit each of the signals [25]. Other components in the fit model take into account background contributions from B−→J/ψ K−and B−→J/ψπ−decays combined with a random π+, B0 s→J/ψη()with η() →π+π−γ, B0 s→J/ψφ with φ→π+π−π0, B0→J/ψ K−π+and Λ0 b→J/ψ K−preflections, and combinatorial backgrounds. The exponential combinatorial background shape is taken from like-sign combinations, that are the sum of π+π+and π−π−candidates. The shapes of the other components are taken from the simulation with their normalizations allowed to vary. Only the candidates within ±20 MeV of the B0mass peak are retained for CP violation measurements; Fig. 2. Invariant mass of J/ψπ+π−combinations with K0 Sveto. The data have been fitted with double-Crystal ball signal and several background functions. The (purple) solid line shows the B0signal, the (brown) dotted line shows the combinatorial background, the (green) short-dashed shows the B−background, the (red) dotdashed is B0 s→J/ψπ+π−, the (light blue) long-dashed is the sum of B0 s→J/ψη, B0 s→J/ψφ when φ→π+π−π0backgrounds and the Λ0 b→J/ψ K−preflection, the (black) dot-long dashed is the B0→J/ψ K−π+reflection and the (blue) solid line is the total. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) the fit gives 17 650 ±200 signal and 9840 ±160 background candidates. 4. The signal likelihood We fit the entire π+π−mass spectrum, by including the resonance contributions found in the amplitude analysis [5], in order to measure the CP-violating parameters of all the states, the most important being (—) B0→J/ψρ0as it has the largest fit fraction of approximately 65%. The same likelihood construction as was used to determine the CP-violating quantities φsand |λ|in (—) B0 s→ J/ψπ+π−decays [6] is employed. Here the value of Γd≈0 simplifies some terms, and the smaller value of mdmakes the decay time resolution function less important. In addition, a different same-sign flavor tagging algorithm is used. The determination of the CP violation parameters relies upon the formalism developed in Ref. [26]. For J/ψ decays to μ+μ− final states the amplitudes are themselves functions of four variables: the π+π−invariant mass mhh =m(π+π−), and three angles Ω, defined in the helicity basis. These consist of: θJ/ψ , the angle between the μ+direction in the J/ψ rest frame with respect to the J/ψ direction in the (—) B0rest frame; θhh, the angle between the h+direction in the h+h−rest frame with respect to the h+h−direction in the (—) B0rest frame; and χ, the angle between the J/ψ and h+h−decay planes in the (—) B0rest frame [26,27]. We perform a simultaneous unbinned maximum likelihood fit to the decay time t, mhh, and the three helicity angles Ω, along with information on the initial flavor of the decaying hadron, i.e. whether it was produced as a B0or a B0meson. The probability density function (PDF) used in the fit consists of signal and background components that include detector resolution and acceptance effects. The predicted decay time error for each event is used for the decay time resolution model, and similarly the measured per-event misidentification probability is used for determining the initial flavor of the neutral Bmeson. The π+π− invariant mass distribution is shown in Fig. 3 along with the fitted components of the different resonances using the “Best model” [5] for the π+π−resonance content. LHCb Collaboration / Physics Letters B 742 (2015) 38–49 41 Fig. 3. Fit projection of m(π+π−)showing the different resonant contributions in the “Best model” [5]. The K0 Sveto causes the absence of events near 500 MeV. The shape variation near 780 MeV is due to interference between the ρ(770)and ω(782)states. The total fit is the sum of the individual components plus their interferences. Knowledge of the (—) B0flavor at production, called “tagging”, is necessary to measure CP violation. We use both opposite-side (OS) [28] and same-side pion (SSπ) tagging information; here we use the same procedure as for same-side kaon tagging used in the (—) B0 s→J/ψπ+π−and J/ψφ analyses [27], but identify the tag from a pion rather than a kaon. The wrong-tag probability η is estimated based on the output of a neural network trained on simulated data. It is calibrated with data using flavor-specific decay modes in order to predict the true wrong-tag probability of the event (—) ω(η)for an initial flavor (—) B0meson, which has a linear dependence on η. The calibration is performed separately for the OS and the SSπtaggers. If events are tagged by both OS and SSπalgorithms, a combined tag decision and wrong-tag probability are given by the algorithm defined in Ref. [28]. This combined algorithm is implemented in the overall fit. The effective tagging power obtained is characterized by εtag D2=(3.26 ±0.17)%, where D ≡(1 −2ωavg)is the dilution, ωavg is the average wrong-tag probability for ωand ¯ ω, and εtag =(42.1 ±0.6)%is the signal tagging efficiency. The signal decay time distribution including flavor tagging is R(ˆ t,mhh,Ω,q|η)=1 1+|q|1+q1−2ω(η)Γ( ˆ t,mhh,Ω) +1−q1−2¯ ω(η)1+AP 1−AP¯ Γ( ˆ t,mhh,Ω) , (8) where ˆ tis the true decay time, (—) Γis defined in Eq. (1), and AP= −0.0035 ±0.0081 [29] is the B0–B0production asymmetry in the LHCb acceptance. The flavor tag parameter qtakes values of −1 or +1 if the signal meson is tagged as B0, B0respectively, or 0 if untagged. The signal function is convolved with the decay time resolution and multiplied by the acceptance: Fsig(t,mhh,Ω,q|η,δ t)=R(ˆ t,mhh,Ω,q|η)⊗T(t−ˆ t;δt) ·Et(t)·ε(mhh,Ω), (9) where ε(mhh, Ω) is the efficiency as a function of the h+h−mass and angles, obtained from the simulation as described in Ref. [5], T(t−ˆ t; δt)is the decay time resolution function which depends upon the estimated decay time error for each event δt, and Et(t) is the decay time acceptance function. The decay time resolution function T(t−ˆ t; δt)is described by a sum of three Gaussian functions with a common mean. Studies using simulated data show that J/ψπ+π−combinations produced directly in the pp interaction (prompt) have nearly identical resolution to signal events. Specifically, the time resolution is determined using prompt J/ψ decays into a dimuon pair, using a dedicated trigger for calibration purposes, plus two oppositely charged tracks from the primary vertex with the similar selection criteria as for J/ψπ+π−and an invariant mass within ±20 MeV of the B0mass. The effective resolution is found to be about 40 fs by using the weighted average widths of the three Gaussians. This is negligibly small compared to the B0–B0oscillation time. The decay time distribution is influenced by acceptance effects that are introduced by track reconstruction, trigger and event selection. The decay time acceptance is obtained using control samples of (—) B0→J/ψ (—) K∗0(→K∓π±)decays, corrected by the acceptance ratio between J/ψ K∓π±and J/ψπ+π−derived from simulation. The acceptance function for the control sample is defined as A(t;a,n,t0,β 1,β 2)=[a(t−t0)]n 1+[a(t−t0)]n×1+β1t+β2t2,(10) where a, n, t0, β1, β2are parameters determined by the fit. The decay time distribution of (—) B0→J/ψ K∓π±candidates is described by the function P0(t)=f0A(t;a,n,t0,β 1,β 2)e−ˆ t/τB0 τB0NB0 +(1−f0)At;a0 bkg,n0 bkg,0,0,0e−ˆ t/τ0 bkg τ0 bkgN0 bkg  ⊗T(t−ˆ t;δt), (11) where f0is the signal fraction, and NB0and N0 bkg are normalizations necessary to construct PDFs of signal and background, respectively. The background acceptance function in Eq. (11) uses the same form as the signal and its parameters a0 bkg, n0 bkg and τ0 bkg are obtained from mass sideband regions of 5180–5205 MeV and 5400–5425 MeV. The lifetime is constrained to τB0=1.519 ±0.007 ps [10]. We use the product of the acceptance A(a, n, t0, β1, β2)determined from (—) B0→J/ψ (—) K∗0and the correction ratio found from simulation as the time acceptance function for (—) B0→J/ψπ+π− events, Et(t;a,n,t0,β 1,β 2,p1,p2) =[a(t−t0)]n 1+[a(t−t0)]n×1+β1t+β2t2×1−p2e−p1t,(12) with parameter values and correlations given in Table 1. 5. Measurements of 2βeff The CP-violating parameters are determined from a fit that uses the amplitude model with six final state π+π−resonances. In our previous amplitude analysis [5] we used two parameterizations of the f0(500)resonance, “default” and “alternate”. The default used a Breit–Wigner resonance shape, with relatively poorly measured parameters, while the alternate used a function suggested by Bugg [30], with more theoretically motivated shape parameters. In this analysis we choose to switch to the shape suggested by Bugg, while the Breit–Wigner shape of the previous default parameterization is used to assess systematic uncertainties. A Gaussian 42 LHCb Collaboration / Physics Letters B 742 (2015) 38–49 Table 1 Parameter values and correlations for the acceptance function εt(t)in Eq. (12). Pn a β1β2t0p1p2Values n1.000 0.444 0.574 −0.536 −0.862 0.000 0.000 2.082 ±0.036 a1.000 0.739 −0.735 −0.050 0.000 0.000 1.981±0.024 ps−1 β11.000 −0.899 −0.374 0.000 0.000 0.077 ±0.009 ps−1 β21.000 0.343 0.000 0.000 −0.008±0.001 ps−2 t01.000 0.000 0.000 0.104 ±0.003 ps p11.000 −0.885 6.237 ±1.669 ps−1 p21.000 −0.739 ±0.424 Table 2 Fit results for 2βeff iand αi CP. Condition 2βeff i(◦)αi CP(×10−3) Fit 1 ρ41.7±9.6+2.8 −6.3ρ−32±28+9 −7 other −ρ3.6±3.6+0.9 −0.8other −1±25+7 −14 Fit 2 ρ044.1±10.2+3.0 −6.9ρ0−47±34+11 −10 ρ−ρ0−0.8±6.5+1.9 −1.3ρ−61±60+8 −6 ρ⊥−ρ0−3.6±7.2+2.0 −1.4ρ⊥17±109+22 −15 other −ρ02.7±3.9+1.0 −0.9other 6 ±27+9 −14 constraint using md=0.510 ±0.003 ps−1[10] is applied in the fit. All other parameters, such as the time resolution, and those describing the tagging are fixed. In addition to the CP-violating parameters, the other free parameters are the amplitudes and phases of the resonances. To minimize correlations in the fitted results, we choose as free parameters the CP asymmetry αi CP =1−|λi| 1+|λi|, 2βeff iof the largest polarization component, and 2βeff iof the other components with respect to the largest one. As J/ψρis the final state with the largest contribution, we treat it specially and perform two fits. In both cases all resonances other than the ρshare a common CP violation parameter λ. For Fit 1 the three ρtransversity states share the same CP violation parameter λ, while for Fit 2 each ρtransversity state has its own CP violation parameter λi. The results are shown in Table 2. The statistical uncertainties are within ±15% of the precision estimated using toy Monte Carlo simulation. To determine 2βfwe use the measured value in b →ccs transitions of (42.8+1.6 −1.5)◦found in (—) B0 decays [9]. Our measurement of 2βeff is consistent with this value for both Fit 1 and Fit 2. The correlation between αρ CP and 2βeff ρ is −0.01 in Fit 1. Table 3 shows the correlation matrix for the CP-violating parameters in Fit 2. Table 4 lists the fit fractions and three transversity fractions of contributing resonances from Fit 1, consistent with the results shown in the amplitude analysis [5]. For a P-or D-wave resonance, we report its total fit fraction by summing all three transversity components. This time-dependent analysis determines the phase difference between the CP-odd component of ρ(770)⊥ and the CP-even component of ρ(770)0to be (167 ±11)◦in Fit 1. Table 4 Fit and transversity fractions of contributing resonances from Fit 1. Uncertainties are statistical only. These results are presented only as a cross-check. Component Fit fraction (%) Transversity fractions (%) 0⊥ ρ(770)65.6±1.956.7±1.823.5±1.519.8±1.7 f0(500)20.1±0.71 0 0 f2(1270)7.8±0.664±49±527±5 ω(782)0.64+0.19 −0.13 44 ±14 53 ±14 3+10 −3 ρ(1450)9.0±1.847±11 39 ±12 14 ±8 ρ(1700)3.1±0.729±12 42 ±15 29 ±15 Fig. 4. Decay time distribution of (—) B0→J/ψπ+π−candidates. The signal component is shown with a (red) dashed line, the background with a (black) dotted line, and the (blue) solid line represents the total. The lower plot shows the normalized residual distribution. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) This quantity is not accessible in the time-integrated amplitude analysis. Fig. 4 shows the decay time distribution superimposed with the fit projection. The statistical significances of the CP measurements are ascertained by fitting the data requiring that CP-violating components Table 3 The correlation matrix for the CP-violating parameters determined using Fit 2, where 2βeff i=2βeff i−2βeff ρ0. αother CP αρ0 CP αρ⊥ CP αρ CP 2βeff other 2βeff ρ⊥2βeff ρ2βeff ρ0 αother CP 1.00 −0.62 −0.28 −0.13 0.05 −0.42 −0.19 0.05 αρ0 CP 1.00 0.03 0.16 0.29 0.22 0.16 −0.11 αρ⊥ CP 1.00 −0.21 −0.19 0.59 −0.07 0.10 αρ CP 1.00 0.01 −0.04 −0.25 −0.09 2βeff other 1.00 0.00 0.26 −0.16 2βeff ρ⊥1.00 0.39 −0.08 2βeff ρ1.00 −0.10 2βeff ρ01.00 LHCb Collaboration / Physics Letters B 742 (2015) 38–49 43 Table 5 Results allowing for different CP-violating effects for resonances other than the ρ in an extension of Fit 1. 2βeff i(◦)αi CP (×10−3) ρ41.8±9.6ρ2±39 f0(500)−ρ2.7±3.8f0(500)−58±46 f2(1270)−ρ1.8±7.5f2(1270)9±63 other spin-1 −ρ3.7±11.1otherspin-1 15±58 are zero. We find that for the entire final state, this requirement changes −2times the logarithm of the likelihood (−2 ln L) by 28.6, corresponding to 4.4 standard deviations for four degrees of freedom (ndf), and for the ρ(770)component only, the change is 24.0, corresponding to 4.5 standard deviations for two ndf. Here we only consider the statistical uncertainties. We also perform a fit by extending Fit 1 to allow different CP-violating effects in final states with either the f0(500), the f2(1270), or spin-1 resonances. The results are shown in Table 5. We find that these fits all give consistent values of the CP-violating parameters. The systematic uncertainties evaluated for both fit configurations are summarized for the CP-violating phases in Table 6 and for the magnitudes of the asymmetries in Table 7. They are small compared to the statistical ones. The two largest contributions result from the resonance fit model and the resonance parameters. Fit model uncertainties are determined by adding an additional resonance to the default six-resonance model, either the f0(980), the f0(1500), the f0(1700), or non-resonant π+π−, replacing the f0(500)model by a Breit–Wigner function, and using the alternative Gounaris–Sakurai model shapes [31] for the various ρmesons. The largest variation among those changes is assigned as the systematic uncertainty for modeling. Including a non-resonant component gives the largest negative change on 2βeff for the ρand ρ0 categories. To evaluate the uncertainties due to the fixed parameters of resonances, we repeat the amplitude fit by varying the mass and width of all the resonances used in the six-resonance model within their errors one at a time, and add the changes in quadrature. To evaluate the systematic uncertainties due to the other fixed parameters including those in the decay time acceptance, the background decay time PDF, the m(π+π−)distribution, the angular acceptance, and background mass PDF, the data fit is repeated by varying the fixed parameters from their nominal values according to the error matrix, one hundred times for each source. The matrix elements are determined using simulation, (—) B0→J/ψ (—) K∗0 data, and like-sign J/ψπ±π±data. The r.m.s. of the fitted physics parameter of interest is taken as its uncertainty for each source. The acceptance model for each of the three angles as a function of mhh is determined independently. To evaluate the reliability of this method we parameterize the mass and angle efficiencies as a combination of Legendre polynomials and spherical harmonics that takes into account all correlations. The amplitude fit is repeated using the new acceptance parameterizations; changes are found to be small and taken as the systematic uncertainty. In the nominal fit the background is divided into three sources: background to the ρ0component from (—) B0 s→J/ψη, η→ρ0γ, reflection from (—) B0→J/ψ (—) K∗0when the kaon is misidentified as a pion, and the remaining background. The latter includes the reflections from (—) Λ0 b→J/ψ K∓(—) pdecays, where both the kaon and proton are misidentified, and combinatorial background. The dependence on mhh of the decay time distribution for this remaining background is modeled by using different decay time PDFs in different mhh regions. We also change the background modeling Fig. 5. The magnitude of the penguin induced shift δPon the CP-violating phase in favored decays, assuming SU(3) flavor symmetry, shown in grey or color scale in degrees, as a function of the measured difference 2βf(x-axis) and αCP =1−|λf| 1+|λf| (y-axis). Here we use fixed values for γ=70◦and =0.0534. The projected 68% (solid) and 95% (dashed) confidence levels on δPare shown by the egg-shaped contours. by dividing the remaining background into separate combinatorial and Λ0 breflection components. The fit is repeated with the new background model, and changes are taken as the systematic uncertainty. The systematic uncertainty due to the tagging parameter calibration is given by the difference in quadrature of the statistical uncertainties for each physics parameter between the nominal fit and an alternative fit where the tagging parameters are Gaussian constrained by their total uncertainties. The systematic uncertainty due to the asymmetry of B0−B0meson production is estimated by varying the central value AP=−0.0035 ±0.0081 [29] by its uncertainty. 6. Discussion of results and conclusions We compare the ρ-only Fit 1 result of 2βJ/ψρ=2βeff =(41.7 ± 9.6+2.8 −6.3)◦with the Cabibbo-favored Bto charmonium result, denoted J/ψ K0 S. The measured difference is 2βf=2βJ/ψρ−2βJ/ψ K0 S=−0.9±9.7+2.8 −6.3◦.(13) Since the result is consistent with zero we determine limits on the magnitude of the CP-violating phase shift due to a possible penguin component in b →ccs decays, δP. The limit is evaluated using pseudo-experiments by generating datasets with different values of αCP, 2βJ/ψρ−2βJ/ψ K0 S, and γ=(70.0+7.7 −9.0)◦[9] according to the measured uncertainties, including the correlation of −0.01 between αCP and 2βJ/ψρ. Then δPfor each dataset is calculated using Eq. (7). We find a Gaussian distribution with a 95% confidence level (CL) interval of [−1.05◦, 1.18◦]. This result is consistent with that obtained by projecting a contour of αCP and 2βJ/ψρ−2βJ/ψ K0 Swith regions proportional to the total uncertainties of the two physics variables as shown in Fig. 5. The two reactions (—) B0→J/ψρ0and (—) B0 s→J/ψφ are related by SU(3) symmetry if we also assume that the difference between the φbeing mostly a singlet state, and the ρ0an octet state causes negligible breaking. Taking the magnitudes of the penguin amplitudes a =aand the strong phases θ=θto be equal in (—) B0→J/ψρ0and (—) B0 s→J/ψφ decays, and neglecting higher order diagrams [3], we find δP=(0.05 ±0.56)◦=0.9 ±9.8mrad. At 44 LHCb Collaboration / Physics Letters B 742 (2015) 38–49 Table 6 Systematic uncertainties on CP-violating phases 2βeff i(◦). Statistical uncertainties are also shown. Fit Sources Fit 1 Fit 2 ρother −ρρ 0ρ−ρ0ρ⊥−ρ0other −ρ0 Resonance model +1.85 −5.94 +0.51 −0.33 +1.99 −6.56 +1.35 −0.05 +1.50 −0.59 +0.68 −0.52 Resonance parameters ±1.21 ±0.43 ±1.35 ±0.68 ±0.57 ±0.60 Mass and angular acceptance ±0.27 ±0.05 ±0.28 ±0.21 ±0.16 ±0.05 Angular acc. correlation ±0.22 ±0.03 ±0.22 ±0.21 ±0.08 ±0.03 Decay time acceptance ±0.05 ±0.02 ±0.06 ±0.04 ±0.04 ±0.03 Bkg. mass and angular PDF ±0.43 ±0.09 ±0.47 ±0.22 ±0.26 ±0.11 Bkg. decay time PDF ±0.14 ±0.05 ±0.12 ±0.06 ±0.08 ±0.07 Bkg. model ±0.49 ±0.23 ±0.15 ±0.97 ±0.38 ±0.13 Flavor Tagging ±1.46 ±0.03 ±1.66 ±0.44 ±0.86 ±0.01 Production asymmetry ±0.17 ±0.50 ±0.28 ±0.09 ±0.49 ±0.42 Total systematic uncertainty +2.8 −6.3+0.9 −0.8+3.0 −6.9+1.9 −1.3+2.0 −1.4+1.0 −0.9 Statistical uncertainty ±9.6±3.6±10.2±6.5±7.2±3.9 Table 7 Systematic uncertainties for the magnitude of the asymmetries αi CP (×10−3). Statistical uncertainties are also shown. Fit Sources Fit 1 Fit 2 ρother −ρρ 0ρρ⊥other −ρ0 Resonance model +6.0 −0.0+0.0 −11.4+3.7 −0.0+5.0 −2.7+16.4 −0.0+0.4 −11.0 Resonance parameters ±5.2±6.1±7.8±3.1±9.2±7.3 Mass and angular acceptance ±0.6±0.5±0.8±0.8±1.6±0.7 Angular acc. correlation ±0.2±0.9±0.2±0.9±0.6±0.9 Decay time acceptance ±0.1±0.1±0.2±0.3±1.1±0.1 Bkg. mass and angular PDF ±0.9±1.5±0.8±2.5±4.6±1.2 Bkg. decay time PDF ±0.5±0.4±0.6±0.5±1.7±0.4 Bkg. model ±2.6±2.9±5.2±3.5±0.9±4.6 Flavor Tagging ±2.8±2.5±0.5±1.0±10.7±1.6 Production asymmetry ±3.0±0.5±2.5±1.1±0.4±0.3 Total systematic uncertainty +9 −7+7 −14 +11 −10 +8 −6+22 −15 +9 −14 Statistical uncertainty ±28 ±25 ±34 ±60 ±109 ±27 95% CL, the penguin contribution in (—) B0 s→J/ψφ decay is within the interval from −1.05◦to +1.18◦. Relaxing these assumptions changes the limits on the possible penguin induced shift. Fig. 6 shows how δPvaries as a function of θ−θ, indicating that the 95% CL limit on penguin pollution can increase to at most ±1.2◦. The variation in δPis proportional to a/a. Thus, when changing a/aover the interval 0.5 to 1.5, the limit on the penguin shift at 95% CL varies between ±0.9◦to ±1.8◦, even allowing for maximal breaking between θand θ. It may be expected that the effect of penguin contributions in other decays, such as (—) B0→J/ψ K0 S, should be limited to similar values, even if there is no strict flavor symmetry relating the mode to (—) B0→J/ψρ0. Our limit is consistent with theoretical predictions [32]. We also set limits on the strong decay amplitude. Fig. 7 shows the 68% and 95% confidence levels contours for the penguin amplitude parameters of aand θwith a −2 ln Lchange of 2.3 and 6 units, for ndf equals two, including systematic uncertainties. They are obtained by converting the corresponding contours for αJ/ψρ CP and 2βfusing their relationship given in Eq. (5). The uncertainty on the angle γ=(70.0+7.7 −9.0)◦only introduces about a 0.2% increase in the mean contour radius of aversus θ. The one-dimensional 68% confidence level intervals are found by changing −2 ln Lby one unit, giving a<0.12 and θ∈(190◦, 355◦), or a=0.035+0.082 −0.035 and θ=(285+69 −95)◦. The decay (—) B0→J/ψπ0proceeds through a similar diagram to that shown in Fig. 1, and thus the CP-violating parameters S and Cshould be similar to those we find in (—) B0→J/ψρ0. These parameters are related to the parameter λfvia the relationships Fig. 6. The limit on the penguin induced phase change δPas a function of the difference in the penguin amplitude strong phases in b →c¯ cs and b →c¯ cd transitions θ−θ, for a =a. Sf≡2Im(λ f) 1+|λf|2=−2ηf|λf|sin 2βeff f 1+|λf|2, and Cf≡1−|λf|2 1+|λf|2,(14) where we set the CP eigenvalue ηf=1to compare with the CP-even mode (—) B0→J/ψπ0. Using Sfand Cfas fit parameters, we obtain from Fit 1 SJ/ψρ=−0.66+0.13+0.09 −0.12−0.03 and CJ/ψρ=−0.063 ±0.056+0.019 −0.014, with a correlation of −0.01. Table 8 shows the comparison of Sfand Cf LHCb Collaboration / Physics Letters B 742 (2015) 38–49 45 Table 8 Comparison of Sfand Cfbetween different measurements. fExperiment SfCfCorrelation (—) B0→J/ψρ0LHCb −0.66+0.13+0.09 −0.12−0.03 −0.063 ±0.056+0.019 −0.014 −0.01 (stat) (—) B0→J/ψπ0Belle [33] −0.65 ±0.21 ±0.05 −0.08 ±0.16 ±0.05 −0.10 (stat) (—) B0→J/ψπ0BaBar [34] −1.23 ±0.21 ±0.04 −0.20 ±0.19 ±0.03 0.20 (stat) Fig. 7. Contours corresponding to 68% (dashed) and 95% (solid) confidence levels for ndf of two, respectively, for the penguin amplitude parameters aand θ. from this measurement with that obtained from the Belle [33] and BaBar [34] Collaborations. Our measurements are in good agreement with the Belle results. In conclusion, the measured value of the penguin contribution is δP=(0.05 ±0.56)◦=0.9 ±9.8mrad. Taking the maximum breaking in phase and a range of breaking 0.5 <a/a<1.5the uncertainty on δPbecomes ±18 mrad. The measured value of φs currently has an uncertainty of about 35 mrad, and the value of 2βof 1.5◦or 26 mrad [9]. Thus our limit is smaller than the current uncertainties, but will need to become more precise as the CP-phase measurements improve. Acknowledgements We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG, HGF and MPG (Germany); SFI (Ireland); INFN (Italy); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FANO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). The Tier1 computing centres are supported by IN2P3 (France), KIT and BMBF (Germany), INFN (Italy), NWO and SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom). We are indebted to the communities behind the multiple open source software packages on which we depend. We are also thankful for the computing resources and the access to software R&D tools provided by Yandex LLC (Russia). Individual groups or members have received support from EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union), Conseil général de Haute-Savoie, Labex ENIGMASS and OCEVU, Région Auvergne (France), RFBR (Russia), XuntaGal and GENCAT (Spain), Royal Society and Royal Commission for the Exhibition of 1851 (United Kingdom). References [1] S. Glashow, Partial symmetries of weak interactions, Nucl. Phys. 22 (1961) 579; S. Weinberg, A model of leptons, Phys. Rev. Lett. 19 (1967) 1264. [2] M. Kobayashi, T. Maskawa, CP violation in the renormalizable theory of weak interaction, Prog. Theor. Phys. 49 (1973) 652. [3] R. Fleischer, Recent theoretical developments in CP violation in the Bsystem, Nucl. Instrum. Methods Phys. Res., Sect. A, Accel. Spectrom. Detect. Assoc. Equip. 446 (2000) 1, arXiv:hep-ph/9908340. [4] S. Faller, M. Jung, R. Fleischer, T. Mannel, The golden modes B0→J/ψ KS,L in the era of precision flavor physics, Phys. Rev. D 79 (2009) 014030, arXiv: 0809.0842; S. Faller, R. Fleischer, T. Mannel, Precision physics with B0 s→J/ψφ at the LHC: the quest for new physics, Phys. Rev. D 79 (2009) 014005, arXiv:0810.4248. [5] LHCb Collaboration, R. Aaij, et al., Measurement of the resonant and CP components in B0→J/ψπ+π−decays, Phys. Rev. D 90 (2014) 012003, arXiv: 1404.5673. [6] LHCb Collaboration, R. Aaij, et al., Measurement of the CP-violating phase φsin B0 s→J/ψπ+π−decays, Phys. Lett. B 736 (2014) 186, arXiv:1405.4140. [7] A.S. Dighe, I. Dunietz, H.J. Lipkin, J.L. Rosner, Angular distributions and lifetime differences in B0 s→J/ψφ decays, Phys. Lett. B 369 (1996) 144, arXiv:hep-ph/ 9511363. [8] I.I. Bigi, A. Sanda, CP violation, Camb. Monogr. Part. Phys. Nucl. Phys. Cosmol. 9 (2000) 1. [9] Heavy Flavor Averaging Group, Y. Amhis, et al., Averages of b-hadron, c-hadron, and τ-lepton properties as of early 2012 and online update at http://www.slac.stanford.edu/xorg/hfag, arXiv:1207.1158, updated results and plots available at: http://www.slac.stanford.edu/xorg/hfag/. [10] Particle Data Group, K. Olive, et al., Review of particle physics, Chin. Phys. C 38 (2014) 090001. [11] R. Fleischer, Extracting CKM phases from angular distributions of Bd,sdecays into admixtures of CP eigenstates, Phys. Rev. D 60 (1999) 073008, arXiv: hep-ph/9903540. [12] LHCb Collaboration, A.A. Alves Jr., et al., The LHCb detector at the LHC, J. Instrum. 3 (2008) S08005. [13] R. Aaij, et al., Performance of the LHCb vertex locator, J. Instrum. 9 (2014) 09007, arXiv:1405.7808. [14] R. Arink, et al., Performance of the LHCb outer tracker, J. Instrum. 9 (2014) P01002, arXiv:1311.3893. [15] M. Adinolfi, et al., Performance of the LHCb RICH detector at the LHC, Eur. Phys. J. C 73 (2013) 2431, arXiv:1211.6759. [16] A.A. Alves Jr., et al., Performance of the LHCb muon system, J. Instrum. 8 (2013) P02022, arXiv:1211.1346. [17] R. Aaij, et al., The LHCb trigger and its performance in 2011, J. Instrum. 8 (2013) P04022, arXiv:1211.3055. [18] T. Sjöstrand, S. Mrenna, P. Skands, PYTHIA 6.4 physics and manual, J. High Energy Phys. 605 (2006) 026, arXiv:hep-ph/0603175; T. Sjöstrand, S. Mrenna, P. Skands, A brief introduction to PYTHIA 8.1, Comput. Phys. Commun. 178 (2008) 852, arXiv:0710.3820. [19] I. Belyaev, et al., Handling of the generation of primary events in Gauss, the LHCb simulation framework, Nucl. Sci. Symp. Conf. Record (NSS/MIC) IEEE (2010) 1155. [20] D.J. Lange, The EvtGen particle decay simulation package, Nucl. Instrum. Methods Phys. Res., Sect. A, Accel. Spectrom. Detect. Assoc. Equip. 462 (2001) 152. [21] P. Golonka, Z. Was, PHOTOS Monte, Carlo: a precision tool for QED corrections in Zand Wdecays, Eur. Phys. J. C 45 (2006) 97, arXiv:hep-ph/0506026. [22] Geant4 Collaboration, J. Allison, et al., Geant4 developments and applications, IEEE Trans. Nucl. Sci. 53 (2006) 270; Geant4 Collaboration, S. Agostinelli, et al., GEANT4: a simulation toolkit, Nucl. Instrum. Methods Phys. Res., Sect. A, Accel. Spectrom. Detect. Assoc. Equip. 506 (2003) 250. [23] M. Clemencic, et al., The LHCb simulation application, Gauss: design, evolution and experience, J. Phys. Conf. Ser. 331 (2011) 032023. [24] L. Breiman, J.H. Friedman, R.A. Olshen, C.J. Stone, Classification and regression trees, Wadsworth International Group, Belmont, California, USA, 1984. 46 LHCb Collaboration / Physics Letters B 742 (2015) 38–49 [25] T. Skwarnicki, A study of the radiative cascade transitions between the Upsilonprime and Upsilon resonances, PhD thesis, Institute of Nuclear Physics, Krakow, 1986, DESY-F31-86-02. [26] L. Zhang, S. Stone, Time-dependent Dalitz-plot formalism for B0 q→J/ψh+h−, Phys. Lett. B 719 (2013) 383, arXiv:1212.6434. [27] LHCb Collaboration, R. Aaij, et al., Measurement of CP violation and the B0 s meson decay width difference with B0 s→J/ψ K+K−and B0 s→J/ψπ+π− decays, Phys. Rev. D 87 (2013) 112010, arXiv:1304.2600. [28] LHCb Collaboration, R. Aaij, et al., Opposite-side flavor tagging of Bmesons at the LHCb experiment, Eur. Phys. J. C 72 (2012) 2022, arXiv:1202.4979. [29] LHCb Collaboration, R. Aaij, et al., Measurement of the B0–B0and B0 s–B0 sproduction asymmetries in pp collisions at √s=7TeV, Phys. Lett. B (2015), in press, arXiv:1408.0275; LHCb Collaboration, R. Aaij, et al., Measurement of the semileptonic CP asymmetry in B0–B0mixing, arXiv:1409.8586. [30] D. Bugg, The mass of the σpole, J. Phys. G 34 (2007) 151, arXiv:hep-ph/ 0608081. [31] G.J. Gounaris, J.J. Sakurai, Finite-width corrections to the vector-mesondominance prediction for ρ→e+e−, Phys. Rev. Lett. 21 (1968) 244. [32] X. Liu, W. Wang, Y. Xie, Penguin pollution in B →J/ψ Vdecays and impact on the extraction of the Bs–¯ Bsmixing phase, Phys. Rev. D 89 (2014) 094010, arXiv:1309.0313; H.-n. Li, S. Mishima, Penguin pollution in the B0→J/ψ K0 Sdecay, J. High Energy Phys. 03 (2007) 009, arXiv:hep-ph/0610120; M. Jung, Penguin contributions to B →J/ψ Pdecays, arXiv:1212.4789; M. Ciuchini, M. Pierini, L. Silvestrini, Theoretical uncertainty in sin 2β: an update, arXiv:1102.0392; M. Ciuchini, M. Pierini, L. Silvestrini, The effect of penguins in the Bd→J/ψ K0 S CP asymmetry, Phys. Rev. Lett. 95 (2005) 221804, arXiv:hep-ph/0507290. [33] Belle Collaboration, S. Lee, et al., Improved measurement of time-dependent CP violation in B0→J/ψπ0decays, Phys. Rev. D 77 (2008) 071101, arXiv: 0708.0304. [34] BaBar Collaboration, B. Aubert, et al., Evidence for CP violation in B0→J/ψπ0 decays, Phys. Rev. Lett. 101 (2008) 021801, arXiv:0804.0896. LHCb Collaboration R. Aaij 41, B. Adeva 37, M. Adinolfi 46, A. Affolder 52, Z. Ajaltouni 5, S. Akar 6, J. Albrecht 9, F. Alessio 38, M. Alexander 51, S. Ali 41, G. Alkhazov 30, P. Alvarez Cartelle 37, A.A. Alves Jr 25,38, S. Amato 2, S. Amerio 22, Y. Amhis 7, L. An 3, L. Anderlini 17,g, J. Anderson 40, R. Andreassen 57, M. Andreotti 16,f, J.E. Andrews 58, R.B. Appleby 54, O. Aquines Gutierrez 10, F. Archilli 38, A. Artamonov35, M. Artuso 59, E. Aslanides 6, G. Auriemma 25,n, M. Baalouch 5, S. Bachmann 11, J.J. Back 48, A. Badalov 36, C. Baesso 60, W. Baldini 16, R.J. Barlow 54, C. Barschel 38, S. Barsuk 7, W. Barter 47, V. Batozskaya 28, V. Battista 39, A. Bay39, L. Beaucourt 4, J. Beddow 51, F. Bedeschi 23, I. Bediaga 1, S. Belogurov 31, K. Belous 35, I. Belyaev 31, E. Ben-Haim 8, G. Bencivenni 18, S. Benson 38, J. Benton 46, A. Berezhnoy 32, R. Bernet 40, A.B. Bertolin 22, M.-O. Bettler 47, M. van Beuzekom 41, A. Bien11, S. Bifani 45, T. Bird 54, A. Bizzeti 17,i, P.M. Bjørnstad 54, T. Blake 48, F. Blanc 39, J. Blouw 10, S. Blusk 59, V. Bocci 25, A. Bondar34,68, N. Bondar 30,38, W. Bonivento 15, S. Borghi 54, A. Borgia 59, M. Borsato 7, T.J.V. Bowcock 52, E. Bowen 40, C. Bozzi 16, D. Brett 54, M. Britsch 10, T. Britton 59, J. Brodzicka 54, N.H. Brook 46, A. Bursche40, J. Buytaert 38, S. Cadeddu 15, R. Calabrese 16,f, M. Calvi 20,k, M. Calvo Gomez 36,p, P. Campana 18, D. Campora Perez38, A. Carbone14,d, G. Carboni 24,l, R. Cardinale 19,38,j, A. Cardini 15, L. Carson 50, K. Carvalho Akiba 2,38, R.C.M. Casanova Mohr 36, G. Casse 52, L. Cassina 20,k, L. Castillo Garcia 38, M. Cattaneo 38, Ch. Cauet 9, R. Cenci 23,t, M. Charles 8, Ph. Charpentier 38, M. Chefdeville 4, S. Chen 54, S.-F. Cheung 55, N. Chiapolini 40, M. Chrzaszcz 40,26, X. Cid Vidal 38, G. Ciezarek 41, P.E.L. Clarke 50, M. Clemencic 38, H.V. Cliff 47, J. Closier 38, V. Coco 38, J. Cogan 6, E. Cogneras 5, V. Cogoni 15, L. Cojocariu 29, G. Collazuol 22, P. Collins 38, A. Comerma-Montells 11, A. Contu15,38, A. Cook 46, M. Coombes 46, S. Coquereau 8, G. Corti 38, M. Corvo 16,f, I. Counts 56, B. Couturier 38, G.A. Cowan 50, D.C. Craik 48, A.C. Crocombe 48, M. Cruz Torres 60, S. Cunliffe 53, R. Currie 53, C. D’Ambrosio 38, J. Dalseno 46, P. David 8, P.N.Y. David 41, A. Davis 57, K. De Bruyn 41, S. De Capua 54, M. De Cian 11, J.M. De Miranda 1, L. De Paula 2, W. De Silva 57, P. De Simone 18, C.-T. Dean 51, D. Decamp 4, M. Deckenhoff 9, L. Del Buono 8, N. Déléage 4, D. Derkach 55, O. Deschamps 5, F. Dettori 38, A. Di Canto 38, A. Di Domenico 25, H. Dijkstra 38, S. Donleavy 52, F. Dordei 11, M. Dorigo 39, A. Dosil Suárez 37, D. Dossett 48, A. Dovbnya 43, K. Dreimanis 52, G. Dujany 54, F. Dupertuis 39, P. Durante 38, R. Dzhelyadin 35, A. Dziurda 26, A. Dzyuba30, S. Easo 49,38, U. Egede 53, V. Egorychev 31, S. Eidelman 34,68, S. Eisenhardt 50, U. Eitschberger 9, R. Ekelhof 9, L. Eklund 51, I. El Rifai 5, Ch. Elsasser 40, S. Ely 59, S. Esen 11, H.-M. Evans 47, T. Evans 55, A. Falabella 14, C. Färber 11, C. Farinelli 41, N. Farley 45, S. Farry 52, R. Fay 52, D. Ferguson 50, V. Fernandez Albor 37, F. Ferreira Rodrigues 1, M. Ferro-Luzzi 38, S. Filippov 33, M. Fiore 16,f, M. Fiorini 16,f, M. Firlej 27, C. Fitzpatrick 39, T. Fiutowski 27, P. Fol 53, M. Fontana 10, F. Fontanelli 19,j, R. Forty 38, O. Francisco 2, M. Frank 38, C. Frei 38, M. Frosini 17,g, J. Fu 21,38, E. Furfaro 24,l, A. Gallas Torreira 37, D. Galli 14,d, S. Gallorini 22,38, S. Gambetta 19,j, M. Gandelman 2, P. Gandini 59, Y. Gao 3, J. García Pardiñas 37, J. Garofoli 59, J. Garra Tico 47, L. Garrido 36, D. Gascon 36, C. Gaspar 38, U. Gastaldi 16, R. Gauld 55, L. Gavardi 9, G. Gazzoni 5, A. Geraci 21,v, E. Gersabeck 11, M. Gersabeck 54, T. Gershon 48, Ph. Ghez 4, A. Gianelle 22, S. Gianì 39, V. Gibson 47, L. Giubega 29, V.V. Gligorov 38, C. Göbel 60, D. Golubkov 31, A. Golutvin 53,31,38, A. Gomes1,a, C. Gotti 20,k, M. Grabalosa Gándara 5, R. Graciani Diaz 36, L.A. Granado Cardoso 38, E. Graugés 36, E. Graverini 40, G. Graziani 17, A. Grecu29, E. Greening 55, S. Gregson 47, P. Griffith 45, L. Grillo 11, O. Grünberg 63, B. Gui 59,