Measurement of the branching fraction and $CP$ asymmetry in $B^{+}\rightarrow J/\psi \rho^{+}$ decays

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)

CERN-EP-2018-298 LHCb-PAPER-2018-036 June 27, 2019

Measurement of the branching

fraction and CP asymmetry in

B

+

→ J/ψ ρ

+

decays

LHCb collaboration†

Abstract

The branching fraction and direct CP asymmetry of the decay B+_{→ J/ψ ρ}+ _are measured using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to a total integrated luminosity of 3 fb−1. The following results are obtained:

B(B+_{→ J/ψ ρ}+_{) = (3.81}+0.25 −0.24± 0.35) × 10 −5 , ACP_(B+_{→ J/ψ ρ}+_{) =−0.045}+0.056 −0.057± 0.008,

where the first uncertainties are statistical and the second systematic. Both mea-surements are the most precise to date.

Published in Eur. Phys. J. C79 (2019) 537

c

2019 CERN for the benefit of the LHCb collaboration. CC-BY-4.0 licence.

†_{Authors are listed at the end of this paper.}

1

Introduction

In the Standard Model of particle physics, the decayB+_{→ J/ψ ρ}+ _{proceeds predominantly}

via a b → ccd transition involving tree and penguin amplitudes,1 _{as shown in Fig. 1.}

Interference between these two amplitudes can lead to directCP violation that is measured through an asymmetry defined as

ACP

≡ B(B

−_{→ J/ψ ρ}−_{)− B(B}+_{→ J/ψ ρ}+₎

B(B−_{→ J/ψ ρ}−_{) +B(B}+_{→ J/ψ ρ}+₎. (1)

No precise prediction for _ACP exists, though it is expected to have an absolute value . 0.35 [1] assuming isospin symmetry between the B0_{→ J/ψ ρ}0 _{and the B}+_{→ J/ψ ρ}+

decays. Measurements of_ACP _{provide an estimate of the imaginary part of the}

penguin-to-tree amplitude ratio for the b → ccd transition. Similarly to the B0_{→ J/ψ ρ}0 _{decay [2],}

the CP asymmetry is expected to be enhanced in this decay compared to the decay B0

s→ J/ψ φ [3, 4]. Therefore its value can be used to place constraints on penguin effects

in measurements of the CP -violating phase φs from the decay Bs0 → J/ψ φ, assuming

approximate SU(3) flavour symmetry and neglecting exchange and annihilation diagrams. The branching fraction and the value of _ACP _{for B}+_{→ J/ψ ρ}+ _{decays were measured}

previously by the BaBar collaboration to be (5.0±0.7±0.3)×10−5 _{and−0.11±0.12±0.08,}

respectively [5].

In this paper, the branching fraction and the direct CP asymmetry of the decay B+_{→ J/ψ ρ}+ _{are measured using proton-proton (pp) collision data collected with the}

LHCb detector at centre-of-mass energies of 7 TeV (in 2011) and 8 TeV (in 2012), corresponding to a total integrated luminosity of 3 fb−1. The B+ _{→ J/ψ ρ}+ _{decay is}

analysed using the J/ψ→ µ+_µ−_,ρ+_{→ π}+_π0 _{and π}0_{→ γγ decays. Its branching fraction}

is measured relative to that of the abundant decay B+_{→ J/ψ K}+_{, which has the same}

number of charged final-state particles and contains aJ/ψ meson as the decay of interest.

¯b u ¯ c c ¯ d u W+ B+ ⇢+ J/ ¯b u ¯ c c ¯ d u W+ ¯ t, ¯c, ¯u B+ ⇢+ J/

Figure 1: Leading-order Feynman diagrams for the (left) tree and (right) penguin amplitudes contributing to the decay B+_{→ J/ψ ρ}+_.

2

Detector and simulation

The LHCb detector [6, 7] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks. The detector includes a high-precision tracking system consisting of a silicon-strip vertex

1_{Charge conjugation is implied throughout this paper, unless otherwise stated.}

detector surrounding the pp interaction region [8], a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors and straw drift tubes [9] placed downstream of the magnet. The tracking system provides a measurement of the momentum, p, of charged particles with a relative uncertainty that varies from 0.5% at low momentum to 1.0% at 200 GeV/c. 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 pT is the

component of the momentum transverse to the beam, in GeV/c. Different types of charged hadrons are distinguished using information from two ring-imaging Cherenkov (RICH) detectors [10]. Photons, electrons and hadrons are identified by a calorimeter system consisting of scintillating-pad and preshower detectors, an electromagnetic and a hadronic calorimeter. Muons are identified by a system composed of alternating layers of iron and multiwire proportional chambers [11].

The magnetic field deflects oppositely charged particles in opposite directions which can lead to charge-dependent acceptance effects. The configuration with the magnetic field pointing upwards (downwards) bends positively (negatively) charged particles in the horizontal plane towards the centre of the LHC ring. Periodically reversing the magnetic field polarity throughout the data taking sufficiently cancels these acceptance effects for the precision of this measurement. Furthermore, the possible difference in material interactions between positively and negatively charged pions is negligible for this analysis [12].

The online event selection is performed by a trigger [13], which consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, which applies a full event reconstruction. For this analysis, the hardware trigger requires at least one muon with a transverse momentum larger than 1.5 GeV/c in 2011 and 1.8 GeV/c in 2012. The first stage of the software trigger requires either a muon candidate with a momentum larger than 8 GeV/c and a transverse momentum larger than 1 GeV/c, or two muons that form a good quality vertex with an invariant mass greater than 2.7 GeV/c2_{. In the second stage of the software trigger, two particles, identified as}

being muons, must form a good-quality vertex with an invariant mass compatible with the known J/ψ mass [14].

Simulated events are used to study the kinematical properties of the B+_{→ J/ψ ρ}+

and B+_{→ J/ψ K}+ _{decays, to study the background contamination and to evaluate the}

selection efficiencies. In the simulation, _{pp collisions are generated using Pythia [15]} with a specific LHCb configuration [16]. Decays of hadronic particles are described by EvtGen [17], in which final-state radiation is generated using Photos [18]. The interaction of the generated particles with the detector, and its response, are implemented using the Geant4 toolkit [19] as described in Ref. [20].

3

Selection

The same selection criteria are placed on theJ/ψ candidates for both decays, B+_{→ J/ψ ρ}+

and B+_{→ J/ψ K}+_{. Each J/ψ candidate is composed of two tracks compatible with}

being muons that form a good quality common vertex significantly displaced from any reconstructed PV in the event. The invariant mass of this two-track combination must be within _{±100 MeV/c}2 _{of the known J/ψ mass [14].}

For the B+_{→ J/ψ ρ}+ _{decay, eachρ}+ _{candidate is formed from a charged and a neutral}

pion. The charged pion is required to have aχ2

IP value that is inconsistent with originating

from any PV in the event, where χ2

IP is defined as the difference between the

vertex-fit χ2 _{of a given PV reconstructed with and without the particle under consideration.}

The charged pion also needs to have a momentum larger than 3 GeV/c and a transverse momentum larger than 250 MeV/c. To reject background from B+_{→ J/ψ K}∗+ _decays2_,

with K∗+

→ K+_π0_{, where a kaon is misidentified as a pion, a stringent criterion is placed}

on the pion-identification quality, which is mainly derived using information from the two RICH detectors. The neutral pion is reconstructed from two well-separated clusters in the electromagnetic calorimeter. It is required to have apT larger than 800 MeV/c. The

ρ+ _{candidate must have a transverse momentum larger than 800 MeV/c and an invariant}

mass mπ+_γγ between 400 MeV/c2 and 1100 MeV/c2.

For the B+_{→ J/ψ K}+ _{decay, the K}+ _{candidate is selected among particles that fulfil}

the same requirements applied to the charged pion in the B+_{→ J/ψ ρ}+ _{decay, have a}

transverse momentum larger than 800 MeV/c and are identified as a kaons.

The B+ _{candidate is formed from the J/ψ candidate and the ρ}+ _{or K}+ _{candidate by}

requiring that the three reconstructed tracks form a good-quality vertex with significant displacement from the PV. In events with multiple PVs, that with which theB+_candidate

has the smallest χ2

IP is chosen. In addition, theB+ candidate is constrained to originate

from the PV using a kinematic fit [21]. In the B+_{→ J/ψ ρ}+ _{channel, the dimuon invariant}

mass is constrained to the knownJ/ψ mass, and when considering the invariant mass of theB+ _{candidate, the π}0 _{candidate is additionally constrained to its known mass. This}

χ2

IP value is required to be small enough to be consistent with the B+ meson having

originated from the PV.

Decays of b hadrons with an additional charged particle are rejected by ensuring that the quality of theB+ _{decay vertex significantly degrades when the closest additional track}

is included in the vertex fit. Finally, the mass of theB+ _{candidate, m}

J/ψ π+_π0 (m_µ+_µ−_K+),

is required to be between 5100 MeV/c2 _{and 5700 MeV/c}2 _{(5180 MeV/c}2 _{and 5400 MeV/c}2_).

For theB+_{→ J/ψ K}+ _{channel, this selection results in a good signal purity, and no further}

selection criteria are needed.

Two vetoes are applied for the B+_{→ J/ψ ρ}+ _{channel to reject B}+_{→ J/ψ K}+ _and

B+_{→ J/ψ π}+ _{decays combined with a randomπ}0_{: the mass of the combination of theJ/ψ}

and the charged pion candidate, evaluated under both the pion and kaon mass hypotheses, must be outside a 50 MeV/c2 _{window around the known B}+ _mass.

In addition to the preselection discussed above, a multivariate selection is performed on theB+_{→ J/ψ ρ}+_{channel using an artificial neural network from the TMVA package [22,23],}

mainly to reduce combinatorial background. The 12 input variables are as follows: the flight distance and direction angle of the B+ _{candidate, defined as the angle between}

its momentum and the vector connecting its primary and decay vertices; the transverse momentum of the B+ _{and ρ}+ _{candidates; the maximum transverse momentum of the}

two muons, the χ2

IP of the charged pion; the minimum χ2IP of the two muons; the quality

of the B+ _{candidate vertex; the change in the vertex quality when adding the closest}

track that is not part of the signal candidate; the quality of a kinematic fit of the full decay chain; the quality of the π0 _{identification; and the p}

T asymmetry in a cone around

the flight direction of the B+ _{meson, defined as (}P

ipTi− P jpTj)/( P ipTi+ P jpTj),

where i runs over all final state tracks of B+_{→ J/ψ ρ}+ _{and j over all other tracks in a}

cone around the B+ _{meson flight direction. The classifier is trained using background}

events from both a lower (4800–5000 MeV/c2_{) and upper (5700–6000 MeV/c}2_{) sideband}

of theB+ _{candidate mass and simulated signal decays, where the p}

T distribution of the

B+ _{meson and the number of tracks per event are weighted to match the corresponding}

distributions in a B0_{→ J/ψ K}∗0 _{data sample, where K}∗0_{→ K}+_π−_{. The B}0_{→ J/ψ K}∗0

candidates are obtained using the same preselection on the charged particles as for the B+_{→ J/ψ ρ}+ _{decay, except that a looser particle-identification criterion is used for the}

pion. Moderate criteria are placed on the kaon p, pT and particle identification to obtain

a good signal purity. For quantities depending on the kinematics of the π0 _{meson, the}

channel B+_{→ J/ψ K}∗+_{, with K}∗+

→ K+_π0_{, is used to compare the distributions of the}

input variables between simulation and data. For all variables good agreement is found. The neural network selection criterion is optimized by maximizing the figure of merit Nsig/pNsig+Nbg, where Nsig is the expected number of signal decays and Nbg is the

estimated background yield, both between 5200 MeV/c2_{and 5450 MeV/c}2_{. The value ofN} sig

is calculated using the ratio of the previously measured B+_{→ J/ψ ρ}+ _{and B}+_{→ J/ψ K}+

branching fractions [14], the observed number ofB+_{→ J/ψ K}+_{decays, and the efficiencies}

of the B+ _{→ J/ψ ρ}+ _{and B}+ _{→ J/ψ K}+ _{channels. The value of N}

bg is obtained by

extrapolating the shape of the background into the signal region. The optimized cut rejects 99.4% of background events in both, the 2011 and 2012 data samples, while retaining 49% (45%) of signal events in the 2011 (2012) data samples.

After applying the full selection for B+_{→ J/ψ ρ}+ _{decays, about 9% of events have}

more than one candidate. Most of these events contain a genuine B+_{→ J/ψ ρ}+ _decay,

along with a candidate comprised of the charged particles from the signal decay combined with a prompt π0 _{meson. The latter constitutes a peaking background that is difficult to}

model, and therefore, events with multiple candidates are removed from the analysis. The efficiency of this rejection is evaluated on simulated samples. The sample of B+_{→ J/ψ K}+

decays contains only 0.2% events with multiple candidates and no rejection is required.

4

Efficiencies

The branching ratio of the decay B+_{→ J/ψ ρ}+ _{is calculated using}

B(B+ → J/ψ ρ+_{) =} B(B+ → J/ψ K+₎ ×_NNB+→J/ψ ρ+ B+_{→J/ψ K}+ × εB+_{→J/ψ K}+ εB+_{→J/ψ ρ}+ × 1 B(π0_{→ γγ)}, (2)

with NB+_{→J/ψ ρ}+ (N_B+_{→J/ψ K}+) the number of measured B+ → J/ψ ρ+ (B+→ J/ψ K+)

decays and εB+_{→J/ψ ρ}+ (ε_B+_{→J/ψ K}+) the efficiency for the B+→ J/ψ ρ+ (B+→ J/ψ K+)

channel. The efficiencies εB+_{→J/ψ K}+ and ε_B+_{→J/ψ ρ}+ are composed of the geometrical

acceptance, trigger, reconstruction, particle identification and selection efficiencies. In addition, there is an efficiency due to the removal of multiple candidates in theB+_{→ J/ψ ρ}+

sample. The efficiency for the decay products of a B+_{→ J/ψ ρ}+ _orB+_{→ J/ψ K}+ _decay

to be within the acceptance of the LHCb detector is taken from simulation. The efficiency to trigger on one or both muons from the J/ψ decay is also taken from simulation. When forming the ratio of branching fractions between the B+_{→ J/ψ ρ}+ _{and B}+_{→ J/ψ K}+

The charged-particle reconstruction efficiency is taken from simulation with kinematics-dependent correction factors applied that are determined using a tag-and-probe technique applied on a detached J/ψ→ µ+_µ− _{data sample [24]. The π}0 _{reconstruction efficiency is}

also obtained from simulation, with a pT-dependent correction factor obtained from the

deviation between the known and observed ratio of branching fractions ofB+_{→ J/ψ K}+

and B+_{→ J/ψ K}∗+ _{decays, with K}∗+_{→ K}+_π0 _{followed by π}0_{→ γγ [25]. Data samples}

of B+_{→ J/ψ K}+ _{and B}+_{→ J/ψ K}∗+ _{decays, collected in 2011 and 2012 by the LHCb}

experiment, are fitted to obtain the number of observed decays. After correcting for the charged-particle selection efficiencies, the double ratio between the ratio of observed decays and the ratio of known branching fractions is the efficiency to reconstruct a π0

meson. This result is compared to the π0 _{efficiency obtained from simulated samples}

to determine the correction factors in intervals of the pT of the π0 meson. Using this

procedure, the uncertainty on the branching fraction of theB+_{→ J/ψ K}+ _{decay cancels}

in the measurement of theB+_{→ J/ψ ρ}+ _{branching fraction, and only the uncertainty on}

the branching fraction of the B+_{→ J/ψ K}∗+ _{decay contributes.}

The charged-particle identification efficiency is evaluated using a tag-and-probe tech-nique on dedicated calibration data samples with clean signatures [26]. Given the similar kinematics for the muons from B+_{→ J/ψ ρ}+ _andB+_{→ J/ψ K}+ _{decays, the muon}

iden-tification efficiency fully cancels when forming the ratio of branching fractions. The charged-pion identification efficiency is 72% for the 2011 data and 74% for the 2012 data. The efficiencies for identifying positively and negatively charged pions are compatible within their statistical uncertainties. The efficiency for identifying the kaon is above 95% for both data taking periods.

The remaining offline selection efficiencies are taken from simulation, where all kine-matic distributions for the signal decay are found to be compatible with the corresponding distributions observed in data for B0_{→ J/ψ K}∗0 _{and B}+_{→ J/ψ K}∗+ _decays.

5

Invariant mass fits

The yield of B+_{→ J/ψ K}+ _{decays is determined using an extended unbinned}

maximum-likelihood fit to the mµ+_µ−_K+ distribution. The signal shape is described using the sum

of two Crystal Ball functions [27] and a Gaussian function, where all three functions share the peak position value. The tail parameters of the Crystal Ball functions are fixed to the values obtained from simulation. An exponential function is used to model the combinatorial background. The fit yields a total of 362 739 _{± 992 B}+_{→ J/ψ K}+ _decays

in 2011 and 816 197 _{± 1545 in 2012. The fit is performed separately for the two magnet} polarities; Figure 2 shows the fit to the data taken with down polarity.

The yield of B+_{→ J/ψ ρ}+ _{decays is determined using a simultaneous two-dimensional}

extended unbinned maximum-likelihood fit to the mJ/ψ π+_π0 and m_π+_γγ distributions in

the 2011 and 2012 data sets. The signal shape in mJ/ψ π+_π0 is modelled with the sum

of two Crystal Ball functions with a shared peak position value. The values of the tail parameters are taken from simulation. The signal shape in mπ+_γγ is modelled with a

relativistic Breit–Wigner function

Pρ+(m_π+_γγ) = mπ+_γγΓ(m_π+_γγ)P2Leff+1 J/ψ (m2 ρ+ − m2_π+_γγ)2+m2_ρ+Γ(mπ+_γγ)2 , (3)

5200 5250 5300 5350 5400 m(µ+_µ−_K+_{) [ MeV/c}2_] 0 2000 4000 6000 8000 10000 12000 14000 Candidates / (2.2 Me V /c 2) _Data Sum B+_{→ J/ψ K}+ Background LHCb 2011, Down 5200 5250 5300 5350 5400 m(µ+_µ−_K+_{) [ MeV/c}2_] 0 5000 10000 15000 20000 25000 Candidates / (2.2 Me V /c 2) _Data Sum B+_{→ J/ψ K}+ Background LHCb 2012, Down

Figure 2: The µ+_µ−_K+ _{invariant mass distributions for the (left) 2011 and (right) 2012 data} sets with down magnet polarity.

with Γ(mπ+_γγ) = Γ₀  q q0 3 mρ+ mπ+_γγ   1 + R2_q2 0 1 +R2_q2  . (4)

Here, PJ/ψ is the momentum of the J/ψ meson in the B+ rest frame, q(mπ+_γγ) is the

pion momentum in the dipion rest frame,Leff is the relative angular momentum of the ρ+

meson with respect to the J/ψ , q0 =q(mρ+), Γ₀ is the nominal width, and R is a barrier

factor radius. The tail parameters of the Crystal Ball function, along with mρ+ and Γ₀

of the Breit–Wigner, are fixed to values obtained from a fit to simulated B+_{→ J/ψ ρ}+

decays, generated using the same functional form with input values mρ+ = 768.5 MeV/c2

and Γ0 = 151 MeV/c2. This strategy therefore folds in the effect of the mπ+_γγ resolution

into the Breit–Wigner model, which results in a value of Γ0 = 175 MeV/c2. The relative

angular momentum Leff is fixed to 0.

Non-resonant J/ψ π+_π0 _{decays are described with the same shape as the signal in}

mJ/ψ π+_π0, while inm_π+_γγ a three-body phase-space distribution multiplied by P2

J/ψ is used,

which is motivated by angular momentum conservation. Given the slowly varying shape in mπ+_γγ, no description of the detector resolution is needed. The combinatorial background

is described by an exponential function in mJ/ψ π+_π0 and a first-order polynomial in m_π+_γγ.

Two partially reconstructed backgrounds are included in the B+_{→ J/ψ ρ}+ _{fit. The}

first is the decay B+_{→ J/ψ K}∗+_{, with K}∗+_{→ K}0

Sπ

+ _{and K}0

S→ π

0_π0_{, where one π}0 _is

not reconstructed. The second is the decay B0

s→ J/ψ φ, with φ → π+π

−_π0_{, where one}

charged pion is not reconstructed. As the shapes of both contributions exhibit significant correlations between mJ/ψ π+_π0 and m_π+_γγ, they are described by two-dimensional kernel

density estimators [28] with adaptive kernels determined using simulation.

The final component is the background fromB+_{→ J/ψ K}∗+ _{decays, withK}∗+_{→ K}+_π0_,

where the kaon is misidentified as a pion. Despite the stringent particle-identification criterion applied, a small amount of these decays is present in the final sample. The product of two one-dimensional kernel density estimators is used to describe the shape in the two invariant mass distributions. This background yield is fixed relative to that of the B+_{→ J/ψ K}∗+ _{decay, with K}∗+

→ K0

Sπ

+_{, using the known ratio of the branching}

fractions [14].

5200 5400 5600 m(J/ψ π+_π0_{) [ MeV/c}2_] 0 20 40 60 80 100 120 140 160 Candidates / (10 Me V /c 2) Data Sum B+_{→ J/ψ ρ}+ B+_{→ J/ψ π}+_π0_{(non res)} Combinatorial B+_{→ J/ψ K}∗+_{part reco} B0 s→ J/ψ φ part reco B+_{→ J/ψ K}∗+_{mis ID} LHCb 2011 5200 5400 5600 m(J/ψ π+_π0_{) [ MeV/c}2_] 0 50 100 150 200 250 300 350 Candidates / (10 Me V /c 2) Data Sum B+_{→ J/ψ ρ}+ B+_{→ J/ψ π}+_π0_{(non res)} Combinatorial B+_{→ J/ψ K}∗+_{part reco} B0 s→ J/ψ φ part reco B+_{→ J/ψ K}∗+_{mis ID} LHCb 2012

Figure 3: The J/ψ π+_π0 _{invariant mass distributions for the (left) 2011 and (right) 2012 data} sets. In the legend, “non res” stands for non-resonant background, “part reco” for partially reconstructed background and “mis ID” for background involving a misidentification of a kaon. The mis ID background is small and not visible in these figures.

400 600 800 1000 m(π+_{γγ) [ MeV/c}2_] 0 10 20 30 40 50 60 70 Candidates / (11.67 Me V /c 2) Data Sum B+_{→ J/ψ ρ}+ B+_{→ J/ψ π}+_π0_{(non res)} Combinatorial B+_{→ J/ψ K}∗+_{part reco} B0 s→ J/ψ φ part reco B+_{→ J/ψ K}∗+_{mis ID} LHCb 2011 400 600 800 1000 m(π+_{γγ) [ MeV/c}2_] 0 20 40 60 80 100 120 140 160 Candidates / (11.67 Me V /c 2) Data Sum B+_{→ J/ψ ρ}+ B+_{→ J/ψ π}+_π0_{(non res)} Combinatorial B+_{→ J/ψ K}∗+_{part reco} B0 s→ J/ψ φ part reco B+_{→ J/ψ K}∗+_{mis ID} LHCb 2012

Figure 4: The π+_{γγ invariant mass distributions for the (left) 2011 and (right) 2012 data sets} for m_{J/ψ π}+_π0 between 5250 MeV/c2 and 5310 MeV/c2. The part reco and mis ID backgrounds

are small in the given mass region and not visible in these figures.

and 2012 data set are shown in Fig. 3 for mJ/ψ π+_π0 and in Fig. 4 for m_π+_γγ, where only

events between 5250 MeV/c2 _{and 5310 MeV/c}2 _inm

J/ψ π+_π0 are considered. For the full fit

regions in mJ/ψ π+_π0 andm_π+_γγ a total of 489± 32 (1090 ± 70) signal decays are observed

in 2011 (2012). The fraction of B+_{→ J/ψ π}+_π0 _{decays that do not proceed via the}

ρ+ _{resonance is measured to be (8.4}+6.1

−6.2)% in the mπ+_γγ interval from 400 MeV/c2 to

1100 MeV/c2_.

The value of _ACP is calculated using ACP ₌

ACP

raw− A

prod_{, (5)}

where _ACP

raw is the raw asymmetry, determined from a fit to the 2011 and 2012 data sets,

split by the charge of the B meson, where all fit components are modelled as in the branching fraction measurement; and_Aprod _{is the production asymmetry of B}+ _mesons

in LHCb. For 2011 and 2012 they were measured to be (_{−0.41 ± 0.49 ± 0.11)% and} (_{−0.53 ± 0.31 ± 0.10)%, respectively [29], with the first uncertainty being statistical and}

For the background contribution from the B+_{→ J/ψ K}∗+ _{decay with K}∗+

→ K0

Sπ

+_,

the CP asymmetry is fixed to the known value of (_{−4.8 ± 3.3)% [14] after correcting for} the production asymmetry. For the partially reconstructed background from B0

s→ J/ψ φ

decays, no charge asymmetry is expected, as the final state is identical for both B0

s and

B0

s mesons.

6

Systematic uncertainties

6.1

Uncertainties on the branching fraction

The systematic uncertainties for the branching fraction measurement are summarized in Table 1. The trigger efficiencies are derived from simulation. The ratio of efficiencies for B+_{→ J/ψ K}+ _{and B}+_{→ J/ψ ρ}+ _{decays has a small deviation from unity due to the}

slightly different kinematical distributions of the J/ψ mesons. To account for potential mismodelling of the impact of theK+ _{and ρ}+ _{on the J/ψ trigger efficiency in simulation,}

thepT distributions of the B+ and J/ψ mesons in B+→ J/ψ K+ decays are weighted to

match those inB+_{→ J/ψ ρ}+_{decays, and the trigger efficiency is reevaluated. The resulting}

difference between this ratio of trigger efficiencies and unity is taken as a systematic uncertainty.

For the charged-particle reconstruction efficiency, the correction factors between simulation and data are varied within their uncertainties, and the effect on the ratio of B+_{→ J/ψ ρ}+ _{and B}+_{→ J/ψ K}+ _{decays is evaluated. The uncertainties consist of both}

statistical and systematic components, where the latter are due to the limited precision on the knowledge of the LHCb material budget. Only the contribution of the material budget uncertainty and the different interaction cross-section of pions and kaons with the material significantly contribute to the uncertainty.

The uncertainty on the π0 _{reconstruction efficiency is dominated by the uncertainty}

on the branching fraction of the B+_{→ J/ψ K}∗+ _{decay, which is used in its calculation,}

and the number of B+_{→ J/ψ K}∗+ _{candidates in each kinematic bin. These values are}

added in quadrature to the systematic uncertainty of the method.

The systematic uncertainty for the charged-pion identification efficiency is evaluated by calculating the difference in efficiency between the nominal method, which is performed in intervals of pT, pseudorapidity, and the number of tracks in the event, and an alternative,

unbinned method. In addition, a different quantity for the event multiplicity and a different scheme of interval boundaries are used. All three uncertainties are added in quadrature. A similar procedure is used for the kaon and muon identification efficiencies, resulting in smaller systematic uncertainties.

For B+_{→ J/ψ K}+ _{decays, the uncertainty on the selection efficiency is dominated by}

the limited size of the simulated data set. For the B+_{→ J/ψ ρ}+ _{selection, the largest}

component of this uncertainty arises from potential discrepancies in the π0 _{identification}

variable between simulation and data. The decayB+_{→ J/ψ K}∗+ _{is used to weight the}

distribution of this variable, and the change in the multivariate classifier efficiency with respect to the baseline value is taken as a systematic uncertainty. A smaller contribution comes from the limited size of the simulated data set.

The uncertainty on the procedure to remove multiple-candidate events in the B+_{→ J/ψ ρ}+ _{channel is determined on simulation by calculating the efficiency to}

se-lect events that contain only one candidate, where the simulated events are weighted so that the event occupancy matches that observed in data. In addition, the invariant mass distributions in data are fitted for all events and events that only contain one candidate, where the signal shape is unchanged for both fits, i.e. the peaking background arising when the charged particles from a genuine signal decay are combined with a prompt π0

meson is ignored. The difference in efficiency between data and simulation is taken as a systematic uncertainty.

The two-dimensional kernel density estimators use adaptive kernel widths. The effect of the kernel width is tested by setting it to a constant value, either higher or lower than the default value, and taking the resulting difference in the branching fraction as a systematic uncertainty. The tail parameters of the Crystal Ball function in B+_{→ J/ψ ρ}+ _{decays are}

varied by _{±20% with respect to the baseline values to account for the uncertainties in} the fit to simulation. The value of mρ+ of the Breit–Wigner function is left free to vary,

instead of being fixed to its baseline value. Furthermore, to take a possible difference in the experimental resolution of the ρ+ _{mass between data and simulation into account,}

the value of Γ0 of the Breit–Wigner shape is altered by the difference in the width of the

B+ _{mass peak between data and simulation in the decayB}+_{→ J/ψ K}∗+_{. All differences}

with respect to the branching fraction of the baseline fit are added in quadrature and added to the overall systematic uncertainty. To take possible correlations in the signal shape between mJ/ψ π+_π0 and m_π+_γγ into account, the baseline model is replaced by a

two-dimensional kernel density estimator whose shape is obtained from simulation. The resulting difference in the branching fraction with respect to the baseline model is taken as a systematic uncertainty.

The polarization of the decay products of the B+ _{meson in the B}+_{→ J/ψ ρ}+ _decay

is unknown. Using simulated decays where Leff is set to 1 or 2, the branching fraction

is recalculated and the difference in the observed branching fraction with respect to the baseline result is taken as a systematic uncertainty. As a consistency test, simulated decays with Leff = 0 are studied. A small bias with respect to the baseline branching

fraction is observed, which is corrected for and taken as a systematic uncertainty.

To test the effect of different polarization amplitudes of B+_{→ J/ψ ρ}+ _{in simulation}

and data on the efficiency to reconstruct the decay, the values of the helicity amplitudes fromB0_{→ J/ψ ρ}0 _{[30] are used in the simulation ofB}+_{→ J/ψ ρ}+ _{decays and varied within}

their uncertainties. The largest deviation with respect to the baseline value is taken as a systematic uncertainty.

In order to estimate the systematic uncertainty from the chosen fit range, the fit to determine the branching fraction is repeated 1000 times with random intervals inmJ/ψ π+_π0

and mπ+_γγ larger or smaller than those of the baseline fit. The width of the resulting

distribution of the measured branching fractions of B+_{→ J/ψ ρ}+ _{decays for each interval}

is taken as a systematic uncertainty. A small bias with respect to the baseline result was observed. The bias is corrected for and also taken as a systematic uncertainty.

As an alternative modelling for the nonresonant contribution in mπ+_γγ, the shape is

modelled with the form (PJ/ψ/mB)2 [31], with mB the known mass of the B+ meson [14].

The difference of the branching fraction with respect to the baseline fit is taken as a systematic uncertainty.

A contribution from interference between the nonresonant B+_{→ J/ψ π}+_π0 _{and signal}

B+_{→ J/ψ ρ}+_{decays could arise due to an asymmetric efficiency of the angular distribution}

Table 1: Systematic uncertainties on the branching fraction B(B+_{→ J/ψ ρ}+_).

Source of uncertainty Relative uncertainty [%]

Trigger efficiency 1.4

Charged particle reconstruction efficiency 0.5

π0 _{reconstruction efficiency 6.3}

Hadron identification efficiency 2.1

Muon identification efficiency 0.4

Selection efficiency B+_{→ J/ψ K}+ _0.1

Selection efficiency B+_{→ J/ψ ρ}+ _1.8

Removal of multiple candidates 1.2

Fit function 4.0

B+_{→ J/ψ ρ}+ _{polarization 2.2}

Fit ranges 1.6

Nonresonant line shape 1.5

Neglecting interference 2.8

Quadratic sum 9.1

fraction fit into account, several samples of one million simulated decays are generated including the interference term, where for each sample a different fixed phase for the nonresonant contribution is chosen. The shape of the angular acceptance is taken from the full simulation of B+ _{→ J/ψ ρ}+ _{decays. Each sample is fitted with the baseline}

description, which does not include the interference term. The largest relative difference in the signal yield with respect to the generated value is taken as a systematic uncertainty. To investigate possible exotic resonance contributions, the invariant masses of J/ψ π+ _and

J/ψ π0 _{are inspected and no excess compared to the expectation is found.}

Given the nature of the systematic uncertainties on the π0 _{and charged-particle}

reconstruction efficiencies, the selection efficiency and the removal of multiple candidates, their correlation in 2011 and 2012 is set to 1. All other uncertainties either result from a common fit to the combined data sets of 2011 and 2012 or are treated as uncorrelated.

6.2

Uncertainties on the CP asymmetry

Most systematic uncertainties cancel when calculating the _ACP _{ratio. The remaining}

contributions are listed in Table 2. The largest contributions come from the uncertainty on the knowledge of the directCP asymmetry of the B+_{→ J/ψ K}∗+ _{decay for the partially}

reconstructed background, and the limited knowledge of the production asymmetry for B+ _{mesons in the 2011 and 2012 data sets. The signal model is again replaced by a}

two-dimensional kernel density estimator to take possible correlations into account, taking the difference in the CP -asymmetry results as a systematic uncertainty. The ratio of the positive and negative pion detection efficiencies ε(π+_)/ε(π−_{) has been measured at}

the LHCb experiment [12] and found to be compatible with unity over a broad range of momenta and transverse momenta, with an uncertainty of about 0.5%. This uncertainty is added as a systematic uncertainty for _ACP.

Table 2: Systematic uncertainties on the direct CP asymmetry of B+_{→ J/ψ ρ}+ _decays.

Source of uncertainty Uncertainty

B+ _{production asymmetry and background asymmetry 0.006}

Signal fit function 0.005

Pion detection asymmetry 0.003

Quadratic sum 0.008

where the data set is split 1000 times randomly, instead of by the charge of theB+ _meson,

and the asymmetry is evaluated. As an additional check, simulated decays are added to each of these randomly split samples, corresponding to _{±5% and ±10% asymmetry,} to assess the robustness of the asymmetry fit for a non-zero _ACP _{value. No bias in the}

resulting distributions is observed. The total systematic uncertainty for _ACP _{is formed by}

adding all individual components in quadrature.

7

Results and Summary

Using Eq. (2) the ratio of the branching fractions of the decays B+ _{→ J/ψ ρ}+ _and

B+_{→ J/ψ K}+ _{is determined to be}

B(B+_{→ J/ψ ρ}+₎

B(B+_{→ J/ψ K}+₎ = 0.0378 +0.0025

−0.0024± 0.0035

in a combined fit to the 2011 and 2012 data sets, where the first uncertainty is statistical and the second systematic. The ratio of efficiencies εB+→J/ψ K+

ε_{B+→J/ψ ρ+} is 27.2± 2.0 for the

combination of both data sets, it is dominated by the low efficiency to select a π0 _{with a}

sufficiently high transverse momentum. The branching fraction for the decay B+_{→ J/ψ ρ}+

is B(B+ → J/ψ ρ+ ) = (3.81+0.25−0.24 ± 0.35) × 10 −5 . The CP asymmetry is measured to be

ACP_(B+_{→ J/ψ ρ}+_{) = −0.045}+0.056

−0.057± 0.008.

Both results are the most precise to date and are consistent with previous measurements. Furthermore, the measured value of_ACP _{is consistent with the corresponding measurement}

using B0_{→ J/ψ ρ}0 _{decays, as expected from isospin symmetry [2].}

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); MOST and NSFC (China); CNRS/IN2P3

(France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (USA). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from AvH Foundation (Germany); EPLANET, Marie Sk lodowska-Curie Actions and ERC (European Union); ANR, Labex P2IO and OCEVU, and R´egion Auvergne-Rhˆone-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, and the Thousand Talents Program (China); RFBR, RSF and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Royal Society and the Leverhulme Trust (United Kingdom); Laboratory Directed Research and Development program of LANL (USA).

References

[1] P. Frings, U. Nierste, and M. Wiebusch, Penguin contributions to CP phases in Bd,s

decays to charmonium, Phys. Rev. Lett. 115 (2015) 061802, arXiv:1503.00859. [2] LHCb collaboration, R. Aaij et al., Measurement of the CP -violating phase β in

B0 _{→ J/ψ π}+_π− _{decays and limits on penguin effects, Phys. Lett. B742 (2015) 38,}

arXiv:1411.1634.

[3] S. Faller, R. Fleischer, and 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. [4] R. Fleischer, Extracting CKM phases from angular distributions ofBd,sdecays into

ad-mixtures of CP eigenstates, Phys. Rev. D60 (1999) 073008, arXiv:hep-ph/9903540. [5] BaBar collaboration, B. Aubert et al., Branching fraction and charge asymmetry mea-surements in B → J/ψππ decays, Phys. Rev. D76 (2007) 031101, arXiv:0704.1266. [6] LHCb collaboration, A. A. Alves Jr. et al., The LHCb detector at the LHC, JINST 3

(2008) S08005.

[7] LHCb collaboration, R. Aaij et al., LHCb detector performance, Int. J. Mod. Phys. A30 (2015) 1530022, arXiv:1412.6352.

[8] R. Aaij et al., Performance of the LHCb Vertex Locator, JINST 9 (2014) P09007, arXiv:1405.7808.

[9] R. Arink et al., Performance of the LHCb Outer Tracker, JINST 9 (2014) P01002, arXiv:1311.3893.

[10] M. Adinolfi et al., Performance of the LHCb RICH detector at the LHC, Eur. Phys. J. C73 (2013) 2431, arXiv:1211.6759.

[11] A. A. Alves Jr. et al., Performance of the LHCb muon system, JINST 8 (2013) P02022, arXiv:1211.1346.

[12] LHCb collaboration, R. Aaij et al., Measurement of theD+

s–Ds−production asymmetry

in 7 TeV pp collisions, Phys. Lett. B713 (2012) 186, arXiv:1205.0897.

[13] R. Aaij et al., The LHCb trigger and its performance in 2011, JINST 8 (2013) P04022, arXiv:1211.3055.

[14] Particle Data Group, M. Tanabashi et al., Review of particle physics, Phys. Rev. D98 (2018) 030001.

[15] T. Sj¨ostrand, S. Mrenna, and P. Skands, PYTHIA 6.4 physics and manual, JHEP 05 (2006) 026, arXiv:hep-ph/0603175; T. Sj¨ostrand, S. Mrenna, and P. Skands, A brief introduction to PYTHIA 8.1, Comput. Phys. Commun. 178 (2008) 852, arXiv:0710.3820.

[16] I. Belyaev et al., Handling of the generation of primary events in Gauss, the LHCb simulation framework, J. Phys. Conf. Ser. 331 (2011) 032047.

[17] D. J. Lange, The EvtGen particle decay simulation package, Nucl. Instrum. Meth. A462 (2001) 152.

[18] P. Golonka and Z. Was, PHOTOS Monte Carlo: A precision tool for QED corrections in Z and W decays, Eur. Phys. J. C45 (2006) 97, arXiv:hep-ph/0506026.

[19] 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. Meth. A506 (2003) 250.

[20] M. Clemencic et al., The LHCb simulation application, Gauss: Design, evolution and experience, J. Phys. Conf. Ser. 331 (2011) 032023.

[21] W. D. Hulsbergen, Decay chain fitting with a Kalman filter, Nucl. Instrum. Meth. A552 (2005) 566, arXiv:physics/0503191.

[22] H. Voss, A. Hoecker, J. Stelzer, and F. Tegenfeldt, TMVA - Toolkit for Multivariate Data Analysis, PoS ACAT (2007) 040.

[23] A. Hoecker et al., TMVA 4 — Toolkit for Multivariate Data Analysis. Users Guide., arXiv:physics/0703039.

[24] LHCb collaboration, R. Aaij et al., Measurement of the track reconstruction efficiency at LHCb, JINST 10 (2015) P02007, arXiv:1408.1251.

[25] LHCb collaboration, R. Aaij et al., Evidence for the decay B0 _{→ J/ψ ω and}

measure-ment of the relative branching fractions of B0

s meson decays to J/ψ η and J/ψ η

0_{, Nucl.}

Phys. B867 (2013) 547, arXiv:1210.2631.

[27] T. Skwarnicki, A study of the radiative cascade transitions between the Upsilon-prime and Upsilon resonances, PhD thesis, Institute of Nuclear Physics, Krakow, 1986, DESY-F31-86-02.

[28] K. S. Cranmer, Kernel estimation in high-energy physics, Comput. Phys. Commun. 136 (2001) 198, arXiv:hep-ex/0011057.

[29] LHCb collaboration, R. Aaij et al., Measurement of the B± _{production asymmetry}

and the CP asymmetry in B±

→ J/ψ K± _{decays, Phys. Rev. D95 (2017) 052005,}

arXiv:1701.05501.

[30] LHCb collaboration, R. Aaij et al., Measurement of the resonant and CP components in B0 _{→ J/ψ π}+_π− _{decays, Phys. Rev. D90 (2014) 012003, arXiv:1404.5673.}

[31] LHCb collaboration, R. Aaij et al., Analysis of the resonant components in B0_{→ J/ψ π}+_π−_{, Phys. Rev. D87 (2013) 052001, arXiv:1301.5347.}

LHCb collaboration

R. Aaij28_{, C. Abell´an Beteta}46_{, B. Adeva}43_{, M. Adinolfi}50_{, C.A. Aidala}78_{, Z. Ajaltouni}6_, S. Akar61_{, P. Albicocco}19_{, J. Albrecht}11_{, F. Alessio}44_{, M. Alexander}55_{, A. Alfonso Albero}42_, G. Alkhazov34_{, P. Alvarez Cartelle}57_{, A.A. Alves Jr}43_{, S. Amato}2_{, S. Amerio}24_{, Y. Amhis}8_, L. An3_{, L. Anderlini}18_{, G. Andreassi}45_{, M. Andreotti}17_{, J.E. Andrews}62_{, F. Archilli}28_,

P. d’Argent13_{, J. Arnau Romeu}7_{, A. Artamonov}41_{, M. Artuso}63_{, K. Arzymatov}38_{, E. Aslanides}7_, M. Atzeni46_{, B. Audurier}23_{, S. Bachmann}13_{, J.J. Back}52_{, S. Baker}57_{, V. Balagura}8,b_,

W. Baldini17_{, A. Baranov}38_{, R.J. Barlow}58_{, G.C. Barrand}8_{, S. Barsuk}8_{, W. Barter}58_,

M. Bartolini20_{, F. Baryshnikov}74_{, V. Batozskaya}32_{, B. Batsukh}63_{, A. Battig}11_{, V. Battista}45_, A. Bay45_{, J. Beddow}55_{, F. Bedeschi}25_{, I. Bediaga}1_{, A. Beiter}63_{, L.J. Bel}28_{, S. Belin}23_{, N. Beliy}66_, V. Bellee45_{, N. Belloli}21,i_{, K. Belous}41_{, I. Belyaev}35_{, E. Ben-Haim}9_{, G. Bencivenni}19_,

S. Benson28_{, S. Beranek}10_{, A. Berezhnoy}36_{, R. Bernet}46_{, D. Berninghoff}13_{, E. Bertholet}9_, A. Bertolin24_{, C. Betancourt}46_{, F. Betti}16,44_{, M.O. Bettler}51_{, M. van Beuzekom}28_,

Ia. Bezshyiko46_{, S. Bhasin}50_{, J. Bhom}30_{, S. Bifani}49_{, P. Billoir}9_{, A. Birnkraut}11_{, A. Bizzeti}18,u_, M. Bjørn59_{, M.P. Blago}44_{, T. Blake}52_{, F. Blanc}45_{, S. Blusk}63_{, D. Bobulska}55_{, V. Bocci}27_, O. Boente Garcia43_{, T. Boettcher}60_{, A. Bondar}40,x_{, N. Bondar}34_{, S. Borghi}58,44_{, M. Borisyak}38_, M. Borsato43_{, F. Bossu}8_{, M. Boubdir}10_{, T.J.V. Bowcock}56_{, C. Bozzi}17,44_{, S. Braun}13_,

M. Brodski44_{, J. Brodzicka}30_{, A. Brossa Gonzalo}52_{, D. Brundu}23,44_{, E. Buchanan}50_, A. Buonaura46_{, C. Burr}58_{, A. Bursche}23_{, J. Buytaert}44_{, W. Byczynski}44_{, S. Cadeddu}23_,

H. Cai68_{, R. Calabrese}17,g_{, R. Calladine}49_{, M. Calvi}21,i_{, M. Calvo Gomez}42,m_{, A. Camboni}42,m_, P. Campana19_{, D.H. Campora Perez}44_{, L. Capriotti}16_{, A. Carbone}16,e_{, G. Carboni}26_,

R. Cardinale20_{, A. Cardini}23_{, P. Carniti}21,i_{, L. Carson}54_{, K. Carvalho Akiba}2_{, G. Casse}56_, L. Cassina21_{, M. Cattaneo}44_{, G. Cavallero}20,h_{, R. Cenci}25,p_{, D. Chamont}8_{, M.G. Chapman}50_, M. Charles9_{, Ph. Charpentier}44_{, G. Chatzikonstantinidis}49_{, M. Chefdeville}5_{, V. Chekalina}38_, C. Chen3_{, S. Chen}23_{, S.-G. Chitic}44_{, V. Chobanova}43_{, M. Chrzaszcz}44_{, A. Chubykin}34_,

P. Ciambrone19_{, X. Cid Vidal}43_{, G. Ciezarek}44_{, P.E.L. Clarke}54_{, M. Clemencic}44_{, H.V. Cliff}51_, J. Closier44_{, V. Coco}44_{, J.A.B. Coelho}8_{, J. Cogan}7_{, E. Cogneras}6_{, L. Cojocariu}33_{, P. Collins}44_, T. Colombo44_{, A. Comerma-Montells}13_{, A. Contu}23_{, G. Coombs}44_{, S. Coquereau}42_{, G. Corti}44_, M. Corvo17,g_{, C.M. Costa Sobral}52_{, B. Couturier}44_{, G.A. Cowan}54_{, D.C. Craik}60_,

A. Crocombe52_{, M. Cruz Torres}1_{, R. Currie}54_{, C. D’Ambrosio}44_{, F. Da Cunha Marinho}2_, C.L. Da Silva79_{, E. Dall’Occo}28_{, J. Dalseno}43,v_{, A. Danilina}35_{, A. Davis}3_,

O. De Aguiar Francisco44_{, K. De Bruyn}44_{, S. De Capua}58_{, M. De Cian}45_{, J.M. De Miranda}1_, L. De Paula2_{, M. De Serio}15,d_{, P. De Simone}19_{, C.T. Dean}55_{, D. Decamp}5_{, L. Del Buono}9_, B. Delaney51_{, H.-P. Dembinski}12_{, M. Demmer}11_{, A. Dendek}31_{, D. Derkach}39_{, O. Deschamps}6_, F. Desse8_{, F. Dettori}56_{, B. Dey}69_{, A. Di Canto}44_{, P. Di Nezza}19_{, S. Didenko}74_{, H. Dijkstra}44_, F. Dordei44_{, M. Dorigo}44,y_{, A. Dosil Su´arez}43_{, L. Douglas}55_{, A. Dovbnya}47_{, K. Dreimanis}56_, L. Dufour28_{, G. Dujany}9_{, P. Durante}44_{, J.M. Durham}79_{, D. Dutta}58_{, R. Dzhelyadin}41_, M. Dziewiecki13_{, A. Dziurda}30_{, A. Dzyuba}34_{, S. Easo}53_{, U. Egede}57_{, V. Egorychev}35_, S. Eidelman40,x_{, S. Eisenhardt}54_{, U. Eitschberger}11_{, R. Ekelhof}11_{, L. Eklund}55_{, S. Ely}63_, A. Ene33_{, S. Escher}10_{, S. Esen}28_{, T. Evans}61_{, A. Falabella}16_{, N. Farley}49_{, S. Farry}56_, D. Fazzini21,44,i_{, L. Federici}26_{, P. Fernandez Declara}44_{, A. Fernandez Prieto}43_{, F. Ferrari}16_, L. Ferreira Lopes45_{, F. Ferreira Rodrigues}2_{, M. Ferro-Luzzi}44_{, S. Filippov}37_{, R.A. Fini}15_, M. Fiorini17,g_{, M. Firlej}31_{, C. Fitzpatrick}45_{, T. Fiutowski}31_{, F. Fleuret}8,b_{, M. Fontana}44_, F. Fontanelli20,h_{, R. Forty}44_{, V. Franco Lima}56_{, M. Frank}44_{, C. Frei}44_{, J. Fu}22,q_{, W. Funk}44_, C. F¨arber44_{, M. F´eo Pereira Rivello Carvalho}28_{, E. Gabriel}54_{, A. Gallas Torreira}43_{, D. Galli}16,e_, S. Gallorini24_{, S. Gambetta}54_{, Y. Gan}3_{, M. Gandelman}2_{, P. Gandini}22_{, Y. Gao}3_,

L.M. Garcia Martin76_{, B. Garcia Plana}43_{, J. Garc´ıa Pardi˜nas}46_{, J. Garra Tico}51_{, L. Garrido}42_, D. Gascon42_{, C. Gaspar}44_{, L. Gavardi}11_{, G. Gazzoni}6_{, D. Gerick}13_{, E. Gersabeck}58_,

P. Gironella Gironell42_{, L. Giubega}33_{, K. Gizdov}54_{, V.V. Gligorov}9_{, D. Golubkov}35_,

A. Golutvin57,74_{, A. Gomes}1,a_{, I.V. Gorelov}36_{, C. Gotti}21,i_{, E. Govorkova}28_{, J.P. Grabowski}13_, R. Graciani Diaz42_{, L.A. Granado Cardoso}44_{, E. Graug´es}42_{, E. Graverini}46_{, G. Graziani}18_, A. Grecu33_{, R. Greim}28_{, P. Griffith}23_{, L. Grillo}58_{, L. Gruber}44_{, B.R. Gruberg Cazon}59_, O. Gr¨unberg71_{, C. Gu}3_{, E. Gushchin}37_{, A. Guth}10_{, Yu. Guz}41,44_{, T. Gys}44_{, C. G¨obel}65_, T. Hadavizadeh59_{, C. Hadjivasiliou}6_{, G. Haefeli}45_{, C. Haen}44_{, S.C. Haines}51_{, B. Hamilton}62_, X. Han13_{, T.H. Hancock}59_{, S. Hansmann-Menzemer}13_{, N. Harnew}59_{, S.T. Harnew}50_,

T. Harrison56_{, C. Hasse}44_{, M. Hatch}44_{, J. He}66_{, M. Hecker}57_{, K. Heinicke}11_{, A. Heister}11_, K. Hennessy56_{, L. Henry}76_{, E. van Herwijnen}44_{, J. Heuel}10_{, M. Heß}71_{, A. Hicheur}64_,

R. Hidalgo Charman58_{, D. Hill}59_{, M. Hilton}58_{, P.H. Hopchev}45_{, J. Hu}13_{, W. Hu}69_{, W. Huang}66_, Z.C. Huard61_{, W. Hulsbergen}28_{, T. Humair}57_{, M. Hushchyn}39_{, D. Hutchcroft}56_{, D. Hynds}28_, P. Ibis11_{, M. Idzik}31_{, P. Ilten}49_{, K. Ivshin}34_{, R. Jacobsson}44_{, J. Jalocha}59_{, E. Jans}28_,

A. Jawahery62_{, F. Jiang}3_{, M. John}59_{, D. Johnson}44_{, C.R. Jones}51_{, C. Joram}44_{, B. Jost}44_, N. Jurik59_{, S. Kandybei}47_{, M. Karacson}44_{, J.M. Kariuki}50_{, S. Karodia}55_{, N. Kazeev}39_, M. Kecke13_{, F. Keizer}51_{, M. Kelsey}63_{, M. Kenzie}51_{, T. Ketel}29_{, E. Khairullin}38_{, B. Khanji}44_, C. Khurewathanakul45_{, K.E. Kim}63_{, T. Kirn}10_{, S. Klaver}19_{, K. Klimaszewski}32_,

T. Klimkovich12_{, S. Koliiev}48_{, M. Kolpin}13_{, R. Kopecna}13_{, P. Koppenburg}28_{, I. Kostiuk}28_, S. Kotriakhova34_{, M. Kozeiha}6_{, L. Kravchuk}37_{, M. Kreps}52_{, F. Kress}57_{, P. Krokovny}40,x_, W. Krupa31_{, W. Krzemien}32_{, W. Kucewicz}30,l_{, M. Kucharczyk}30_{, V. Kudryavtsev}40,x_,

A.K. Kuonen45_{, T. Kvaratskheliya}35,44_{, D. Lacarrere}44_{, G. Lafferty}58_{, A. Lai}23_{, D. Lancierini}46_, G. Lanfranchi19_{, C. Langenbruch}10_{, T. Latham}52_{, C. Lazzeroni}49_{, R. Le Gac}7_{, A. Leflat}36_, J. Lefran¸cois8_{, R. Lef`evre}6_{, F. Lemaitre}44_{, O. Leroy}7_{, T. Lesiak}30_{, B. Leverington}13_{, P.-R. Li}66_, Y. Li4_{, Z. Li}63_{, X. Liang}63_{, T. Likhomanenko}73_{, R. Lindner}44_{, F. Lionetto}46_{, V. Lisovskyi}8_, G. Liu67_{, X. Liu}3_{, D. Loh}52_{, A. Loi}23_{, I. Longstaff}55_{, J.H. Lopes}2_{, G.H. Lovell}51_{, D. Lucchesi}24,o_, M. Lucio Martinez43_{, A. Lupato}24_{, E. Luppi}17,g_{, O. Lupton}44_{, A. Lusiani}25_{, X. Lyu}66_,

F. Machefert8_{, F. Maciuc}33_{, V. Macko}45_{, P. Mackowiak}11_{, S. Maddrell-Mander}50_{, O. Maev}34,44_, K. Maguire58_{, D. Maisuzenko}34_{, M.W. Majewski}31_{, S. Malde}59_{, B. Malecki}30_{, A. Malinin}73_, T. Maltsev40,x_{, G. Manca}23,f_{, G. Mancinelli}7_{, D. Marangotto}22,q_{, J. Maratas}6,w_{, J.F. Marchand}5_, U. Marconi16_{, C. Marin Benito}8_{, M. Marinangeli}45_{, P. Marino}45_{, J. Marks}13_{, P.J. Marshall}56_, G. Martellotti27_{, M. Martin}7_{, M. Martinelli}44_{, D. Martinez Santos}43_{, F. Martinez Vidal}76_, A. Massafferri1_{, M. Materok}10_{, R. Matev}44_{, A. Mathad}52_{, Z. Mathe}44_{, C. Matteuzzi}21_, A. Mauri46_{, E. Maurice}8,b_{, B. Maurin}45_{, A. Mazurov}49_{, M. McCann}57,44_{, A. McNab}58_, R. McNulty14_{, J.V. Mead}56_{, B. Meadows}61_{, C. Meaux}7_{, N. Meinert}71_{, D. Melnychuk}32_, M. Merk28_{, A. Merli}22,q_{, E. Michielin}24_{, D.A. Milanes}70_{, E. Millard}52_{, M.-N. Minard}5_, L. Minzoni17,g_{, D.S. Mitzel}13_{, A. Mogini}9_{, R.D. Moise}57_{, T. Momb¨acher}11_{, I.A. Monroy}70_, S. Monteil6_{, M. Morandin}24_{, G. Morello}19_{, M.J. Morello}25,t_{, O. Morgunova}73_{, J. Moron}31_, A.B. Morris7_{, R. Mountain}63_{, F. Muheim}54_{, M. Mulder}28_{, C.H. Murphy}59_{, D. Murray}58_, A. M¨odden11_{, D. M¨uller}44_{, J. M¨uller}11_{, K. M¨uller}46_{, V. M¨uller}11_{, P. Naik}50_{, T. Nakada}45_, R. Nandakumar53_{, A. Nandi}59_{, T. Nanut}45_{, I. Nasteva}2_{, M. Needham}54_{, N. Neri}22_{, S. Neubert}13_, N. Neufeld44_{, M. Neuner}13_{, R. Newcombe}57_{, T.D. Nguyen}45_{, C. Nguyen-Mau}45,n_{, S. Nieswand}10_, R. Niet11_{, N. Nikitin}36_{, A. Nogay}73_{, N.S. Nolte}44_{, D.P. O’Hanlon}16_{, A. Oblakowska-Mucha}31_, V. Obraztsov41_{, S. Ogilvy}19_{, R. Oldeman}23,f_{, C.J.G. Onderwater}72_{, A. Ossowska}30_,

J.M. Otalora Goicochea2_{, T. Ovsiannikova}35_{, P. Owen}46_{, A. Oyanguren}76_{, P.R. Pais}45_, T. Pajero25,t_{, A. Palano}15_{, M. Palutan}19_{, G. Panshin}75_{, A. Papanestis}53_{, M. Pappagallo}54_, L.L. Pappalardo17,g_{, W. Parker}62_{, C. Parkes}58,44_{, G. Passaleva}18,44_{, A. Pastore}15_{, M. Patel}57_, C. Patrignani16,e_{, A. Pearce}44_{, A. Pellegrino}28_{, G. Penso}27_{, M. Pepe Altarelli}44_{, S. Perazzini}44_, D. Pereima35_{, P. Perret}6_{, L. Pescatore}45_{, K. Petridis}50_{, A. Petrolini}20,h_{, A. Petrov}73_,

S. Petrucci54_{, M. Petruzzo}22,q_{, B. Pietrzyk}5_{, G. Pietrzyk}45_{, M. Pikies}30_{, M. Pili}59_{, D. Pinci}27_, J. Pinzino44_{, F. Pisani}44_{, A. Piucci}13_{, V. Placinta}33_{, S. Playfer}54_{, J. Plews}49_{, M. Plo Casasus}43_, F. Polci9_{, M. Poli Lener}19_{, A. Poluektov}52_{, N. Polukhina}74,c_{, I. Polyakov}63_{, E. Polycarpo}2_,

G.J. Pomery50_{, S. Ponce}44_{, A. Popov}41_{, D. Popov}49,12_{, S. Poslavskii}41_{, C. Potterat}2_{, E. Price}50_, J. Prisciandaro43_{, C. Prouve}50_{, V. Pugatch}48_{, A. Puig Navarro}46_{, H. Pullen}59_{, G. Punzi}25,p_, W. Qian66_{, J. Qin}66_{, R. Quagliani}9_{, B. Quintana}6_{, B. Rachwal}31_{, J.H. Rademacker}50_, M. Rama25_{, M. Ramos Pernas}43_{, M.S. Rangel}2_{, F. Ratnikov}38,39_{, G. Raven}29_,

M. Ravonel Salzgeber44_{, M. Reboud}5_{, F. Redi}45_{, S. Reichert}11_{, A.C. dos Reis}1_{, F. Reiss}9_, C. Remon Alepuz76_{, Z. Ren}3_{, V. Renaudin}8_{, S. Ricciardi}53_{, S. Richards}50_{, K. Rinnert}56_, P. Robbe8_{, A. Robert}9_{, A.B. Rodrigues}45_{, E. Rodrigues}61_{, J.A. Rodriguez Lopez}70_, M. Roehrken44_{, S. Roiser}44_{, A. Rollings}59_{, V. Romanovskiy}41_{, A. Romero Vidal}43_,

M. Rotondo19_{, M.S. Rudolph}63_{, T. Ruf}44_{, J. Ruiz Vidal}76_{, J.J. Saborido Silva}43_{, N. Sagidova}34_, B. Saitta23,f_{, V. Salustino Guimaraes}65_{, C. Sanchez Gras}28_{, C. Sanchez Mayordomo}76_,

B. Sanmartin Sedes43_{, R. Santacesaria}27_{, C. Santamarina Rios}43_{, M. Santimaria}19,44_, E. Santovetti26,j_{, G. Sarpis}58_{, A. Sarti}19,k_{, C. Satriano}27,s_{, A. Satta}26_{, M. Saur}66_,

D. Savrina35,36_{, S. Schael}10_{, M. Schellenberg}11_{, M. Schiller}55_{, H. Schindler}44_{, M. Schmelling}12_, T. Schmelzer11_{, B. Schmidt}44_{, O. Schneider}45_{, A. Schopper}44_{, H.F. Schreiner}61_{, M. Schubiger}45_, M.H. Schune8_{, R. Schwemmer}44_{, B. Sciascia}19_{, A. Sciubba}27,k_{, A. Semennikov}35_,

E.S. Sepulveda9_{, A. Sergi}49,44_{, N. Serra}46_{, J. Serrano}7_{, L. Sestini}24_{, A. Seuthe}11_{, P. Seyfert}44_, M. Shapkin41_{, Y. Shcheglov}34,†_{, T. Shears}56_{, L. Shekhtman}40,x_{, V. Shevchenko}73_{, E. Shmanin}74_, B.G. Siddi17_{, R. Silva Coutinho}46_{, L. Silva de Oliveira}2_{, G. Simi}24,o_{, S. Simone}15,d_{, I. Skiba}17_, N. Skidmore13_{, T. Skwarnicki}63_{, M.W. Slater}49_{, J.G. Smeaton}51_{, E. Smith}10_{, I.T. Smith}54_, M. Smith57_{, M. Soares}16_{, l. Soares Lavra}1_{, M.D. Sokoloff}61_{, F.J.P. Soler}55_{, B. Souza De Paula}2_, B. Spaan11_{, E. Spadaro Norella}22,q_{, P. Spradlin}55_{, F. Stagni}44_{, M. Stahl}13_{, S. Stahl}44_,

P. Stefko45_{, S. Stefkova}57_{, O. Steinkamp}46_{, S. Stemmle}13_{, O. Stenyakin}41_{, M. Stepanova}34_, H. Stevens11_{, A. Stocchi}8_{, S. Stone}63_{, B. Storaci}46_{, S. Stracka}25_{, M.E. Stramaglia}45_,

M. Straticiuc33_{, U. Straumann}46_{, S. Strokov}75_{, J. Sun}3_{, L. Sun}68_{, K. Swientek}31_{, A. Szabelski}32_, T. Szumlak31_{, M. Szymanski}66_{, S. T’Jampens}5_{, Z. Tang}3_{, A. Tayduganov}7_{, T. Tekampe}11_, G. Tellarini17_{, F. Teubert}44_{, E. Thomas}44_{, J. van Tilburg}28_{, M.J. Tilley}57_{, V. Tisserand}6_, M. Tobin31_{, S. Tolk}44_{, L. Tomassetti}17,g_{, D. Tonelli}25_{, D.Y. Tou}9_{, R. Tourinho Jadallah Aoude}1_, E. Tournefier5_{, M. Traill}55_{, M.T. Tran}45_{, A. Trisovic}51_{, A. Tsaregorodtsev}7_{, G. Tuci}25,p_, A. Tully51_{, N. Tuning}28,44_{, A. Ukleja}32_{, A. Usachov}8_{, A. Ustyuzhanin}38_{, U. Uwer}13_, A. Vagner75_{, V. Vagnoni}16_{, A. Valassi}44_{, S. Valat}44_{, G. Valenti}16_{, R. Vazquez Gomez}44_, P. Vazquez Regueiro43_{, S. Vecchi}17_{, M. van Veghel}28_{, J.J. Velthuis}50_{, M. Veltri}18,r_, G. Veneziano59_{, A. Venkateswaran}63_{, M. Vernet}6_{, M. Veronesi}28_{, N.V. Veronika}14_, M. Vesterinen59_{, J.V. Viana Barbosa}44_{, D. Vieira}66_{, M. Vieites Diaz}43_{, H. Viemann}71_, X. Vilasis-Cardona42,m_{, A. Vitkovskiy}28_{, M. Vitti}51_{, V. Volkov}36_{, A. Vollhardt}46_, D. Vom Bruch9_{, B. Voneki}44_{, A. Vorobyev}34_{, V. Vorobyev}40,x_{, J.A. de Vries}28_,

C. V´azquez Sierra28_{, R. Waldi}71_{, J. Walsh}25_{, J. Wang}4_{, M. Wang}3_{, Y. Wang}69_{, Z. Wang}46_, D.R. Ward51_{, H.M. Wark}56_{, N.K. Watson}49_{, D. Websdale}57_{, A. Weiden}46_{, C. Weisser}60_, M. Whitehead10_{, J. Wicht}52_{, G. Wilkinson}59_{, M. Wilkinson}63_{, I. Williams}51_{, M.R.J. Williams}58_, M. Williams60_{, T. Williams}49_{, F.F. Wilson}53_{, M. Winn}8_{, W. Wislicki}32_{, M. Witek}30_,

G. Wormser8_{, S.A. Wotton}51_{, K. Wyllie}44_{, D. Xiao}69_{, Y. Xie}69_{, A. Xu}3_{, M. Xu}69_{, Q. Xu}66_, Z. Xu3_{, Z. Xu}5_{, Z. Yang}3_{, Z. Yang}62_{, Y. Yao}63_{, L.E. Yeomans}56_{, H. Yin}69_{, J. Yu}69,aa_{, X. Yuan}63_, O. Yushchenko41_{, K.A. Zarebski}49_{, M. Zavertyaev}12,c_{, D. Zhang}69_{, L. Zhang}3_{, W.C. Zhang}3,z_, Y. Zhang8_{, A. Zhelezov}13_{, Y. Zheng}66_{, X. Zhu}3_{, V. Zhukov}10,36_{, J.B. Zonneveld}54_{, S. Zucchelli}16_.

1_{Centro Brasileiro de Pesquisas F´ısicas (CBPF), Rio de Janeiro, Brazil} 2_{Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil} 3_{Center for High Energy Physics, Tsinghua University, Beijing, China} 4_{Institute Of High Energy Physics (ihep), Beijing, China}

5_{Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France} 6_{Clermont Universit´e, Universit´e Blaise Pascal, CNRS/IN2P3, LPC, Clermont-Ferrand, France} 7_{Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France}

8_{LAL, Univ. Paris-Sud, CNRS/IN2P3, Universit´e Paris-Saclay, Orsay, France}

9_{LPNHE, Sorbonne Universit´e, Paris Diderot Sorbonne Paris Cit´e, CNRS/IN2P3, Paris, France} 10_{I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany}

11_{Fakult¨at Physik, Technische Universit¨at Dortmund, Dortmund, Germany} 12_{Max-Planck-Institut f¨ur Kernphysik (MPIK), Heidelberg, Germany}

13_{Physikalisches Institut, Ruprecht-Karls-Universit¨at Heidelberg, Heidelberg, Germany} 14_{School of Physics, University College Dublin, Dublin, Ireland}

15_{INFN Sezione di Bari, Bari, Italy} 16_{INFN Sezione di Bologna, Bologna, Italy} 17_{INFN Sezione di Ferrara, Ferrara, Italy} 18_{INFN Sezione di Firenze, Firenze, Italy}

19_{INFN Laboratori Nazionali di Frascati, Frascati, Italy} 20_{INFN Sezione di Genova, Genova, Italy}

21_{INFN Sezione di Milano-Bicocca, Milano, Italy} 22_{INFN Sezione di Milano, Milano, Italy}

23_{INFN Sezione di Cagliari, Monserrato, Italy} 24_{INFN Sezione di Padova, Padova, Italy} 25_{INFN Sezione di Pisa, Pisa, Italy}

26_{INFN Sezione di Roma Tor Vergata, Roma, Italy} 27_{INFN Sezione di Roma La Sapienza, Roma, Italy}

28_{Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands}

29_{Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam,}

Netherlands

30_{Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Krak´ow, Poland} 31_{AGH - University of Science and Technology, Faculty of Physics and Applied Computer Science,}

Krak´ow, Poland

32_{National Center for Nuclear Research (NCBJ), Warsaw, Poland}

33_{Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania} 34_{Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia}

35_{Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia}

36_{Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia}

37_{Institute for Nuclear Research of the Russian Academy of Sciences (INR RAS), Moscow, Russia} 38_{Yandex School of Data Analysis, Moscow, Russia}

39_{National Research University Higher School of Economics, Moscow, Russia} 40_{Budker Institute of Nuclear Physics (SB RAS), Novosibirsk, Russia} 41_{Institute for High Energy Physics (IHEP), Protvino, Russia}

42_{ICCUB, Universitat de Barcelona, Barcelona, Spain}

43_{Instituto Galego de F´ısica de Altas Enerx´ıas (IGFAE), Universidade de Santiago de Compostela,}

Santiago de Compostela, Spain

44_{European Organization for Nuclear Research (CERN), Geneva, Switzerland}

45_{Institute of Physics, Ecole Polytechnique F´ed´erale de Lausanne (EPFL), Lausanne, Switzerland} 46_{Physik-Institut, Universit¨at Z¨urich, Z¨urich, Switzerland}

47_{NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine}

48_{Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine} 49_{University of Birmingham, Birmingham, United Kingdom}

50_{H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom} 51_{Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom} 52_{Department of Physics, University of Warwick, Coventry, United Kingdom} 53_{STFC Rutherford Appleton Laboratory, Didcot, United Kingdom}

54_{School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom} 55_{School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom} 56_{Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom} 57_{Imperial College London, London, United Kingdom}

58_{School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom} 59_{Department of Physics, University of Oxford, Oxford, United Kingdom}