EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)

 CERN-PH-EP-2015-076 LHCb-PAPER-2015-004 March 24, 2015

Measurement of $C\\!P$ violation in
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ decays

The LHCb collaboration†††Authors are listed at the end of this Letter.

Measurements are presented of the $C\\!P$ violation observables $S$ and $C$ in
the decays of $B^{0}$ and ${\kern 1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$
mesons to the ${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ final state. The data sample
corresponds to an integrated luminosity of
$3.0\text{\,}\mathrm{f}\mathrm{b}^{-1}$ collected with the LHCb experiment in
proton-proton collisions at center-of-mass energies of $7$ and
$8\text{\,}\mathrm{TeV}$. The analysis of the time evolution of $41\,500$
$B^{0}$ and ${\kern 1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ decays yields
$S=0.731\pm 0.035\,\text{(stat)}\pm 0.020\,\text{(syst)}$ and $C=-0.038\pm
0.032\,\text{(stat)}\pm 0.005\,\text{(syst)}$. In the Standard Model, $S$
equals $\sin(2\beta)$ to a good level of precision. The values are consistent
with the current world averages and with the Standard Model expectations.

Submitted to Phys. Rev. Lett.

© CERN on behalf of the LHCb collaboration, license CC-BY-4.0.

The violation of charge-parity ($C\\!P$) conservation in processes involving
$B$ mesons was first observed in the “golden mode”
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ by the BaBar and Belle experiments at
the asymmetric $e^{+}e^{-}$ colliders PEP-II and KEKB [1, 2]. Since then,
measurements of $C\\!P$ violation in this decay mode have reached a precision
at the level of $10^{-2}$ [3, 4]. Thus, these measurements play an important
role in constraining and testing the quark-flavor sector of the Standard Model
[5, 6], which relates $C\\!P$-violating observables to a single irreducible
phase in the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix [7, 8]. As
the ${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}{K^{0}_{\rm\scriptscriptstyle
S}}$ final state is common to both the $B^{0}$ and the ${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ meson decays, the interference
between the amplitudes for the direct decay and for the decay after
$B^{0}$–${\kern 1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ oscillation
results in a decay-time dependent $C\\!P$ asymmetry between the time-dependent
decay rates of $B^{0}$ and ${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ mesons,

$\mathcal{A}(t)\equiv\frac{\Gamma({\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}(t)\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle
S}})-\Gamma(B^{0}(t)\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}})}{\Gamma({\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}(t)\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle
S}})+\Gamma(B^{0}(t)\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle
S}})}=\frac{S\sin(\mathrm{\Delta}m\,t)-C\cos(\mathrm{\Delta}m\,t)}{\cosh(\frac{\mathrm{\Delta}\Gamma\,t}{2})+A_{\mathrm{\Delta}\Gamma}\sinh(\frac{\mathrm{\Delta}\Gamma\,t}{2})}.$
(1)

Here, $B^{0}(t)$ and ${\kern 1.79993pt\overline{\kern-1.79993ptB}}{}^{0}(t)$
indicate the flavor of the $B$ meson at production, while $t$ indicates the
decay time. The parameters $\mathrm{\Delta}m$ and $\mathrm{\Delta}\Gamma$ are
the mass and the decay width differences between the heavy and light mass
eigenstates of the $B^{0}$–${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ system, and $S$, $C$, and
$A_{\mathrm{\Delta}\Gamma}$ are $C\\!P$ observables. As
$\mathrm{\Delta}\Gamma$ is negligible for the $B^{0}$–${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ system [9], the time-dependent
asymmetry simplifies to
$\mathcal{A}(t)=S\sin(\mathrm{\Delta}m\,t)-C\cos(\mathrm{\Delta}m\,t)$.

The $B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ decay is dominated by a
$\overline{b}\\!\rightarrow c\overline{c}\,\overline{s}$ transition,111Mention
of a particular decay mode implies the inclusion of charge-conjugate states
except when the measurement of $C\\!P$ violation is involved. and $C\\!P$
violation in the decay is expected to be negligible at the current level of
experimental precision, giving $C\approx 0$. This allows to identify $S$ with
$\sin(2\beta)$, where
$\beta\equiv\arg[-(V_{cd}^{\vphantom{\ast}}V_{cb}^{\ast})/(V_{td}^{\vphantom{\ast}}V_{tb}^{\ast})]$
is one of the angles of the CKM triangle. Other measurements that constrain
this triangle predict $\sin(2\beta)$ as $0.771\pm^{0.017}_{0.041}$ [10],
giving a small discrepancy with respect to the average of direct measurements,
$0.682\pm 0.019$ [9], where the most precise input comes from a $C\\!P$
violation measurement in
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ decays by the Belle experiment,
$S=0.670\pm 0.029\,\text{(stat)}\pm 0.013\,\text{(syst)}$ [4]. To clarify the
CKM picture, both better experimental precision and improved understanding of
higher-order contributions to the decay amplitudes are required [11,
*Aaij:2014vda, 13, *Frings:2015eva].

The analysis presented in this Letter supersedes a previous measurement by
LHCb [15], which was performed on data corresponding to an integrated
luminosity of $1.0\text{\,}{\mathrm{fb}}^{-1}$ at a center-of-mass energy of
$7\text{\,}\mathrm{T}\mathrm{e}\mathrm{V}$. By adding data corresponding to
$2\text{\,}{\mathrm{fb}}^{-1}$ at $8\text{\,}\mathrm{T}\mathrm{e}\mathrm{V}$
and using an optimized selection and additional “flavor tagging” algorithms to
identify the quark content of the $B$ meson at production, we increase the
statistical power of the analysis by almost a factor $6$.

The LHCb detector [16, 17] is a single-arm forward spectrometer covering the
pseudorapidity range $2<\eta<5$, 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 detector surrounding the $pp$
interaction region, a large-area silicon-strip detector located upstream of a
dipole magnet, and three stations of silicon-strip detectors and straw drift
tubes placed downstream of the magnet. Different types of charged hadrons are
distinguished using information from two ring-imaging Cherenkov detectors.
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.
The online event selection system (trigger) [18] consists of a hardware stage,
based on information from the calorimeter and muon systems, followed by a
software stage.

The analysis is performed with
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ candidates reconstructed in the
${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}\\!\rightarrow\mu^{+}\mu^{-}$ and
${K^{0}_{\rm\scriptscriptstyle S}}\\!\rightarrow\pi^{+}\pi^{-}$ final states.
Two oppositely charged particles, identified as muons with high momentum and
high transverse momentum, are required to originate from a common space-point
(vertex) and to have an invariant mass in a range $\pm
60\text{\,}\mathrm{MeV}\text{/}{\mathrm{\mathit{c}}}^{2}$ around the known
${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}$ mass [19]. Since the $B^{0}$
meson has a lifetime of $1.5\text{\,}\mathrm{ps}$ and has high momentum, the
resulting ${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}$ candidate is required
to be significantly separated from all reconstructed $pp$ collision points
(primary vertices (PVs)). The ${K^{0}_{\rm\scriptscriptstyle S}}$ candidates
are formed from two oppositely charged, high-momentum pion candidates with a
clear separation from any PV in the event. Candidates decaying early enough
for the final-state pions to be reconstructed in the vertex detector are
characterized as _long_ candidates and are required to have an invariant mass
within $\pm 15\text{\,}\mathrm{MeV}\text{/}{\mathrm{\mathit{c}}}^{2}$ of the
known ${K^{0}_{\rm\scriptscriptstyle S}}$ mass [19]. The
${K^{0}_{\rm\scriptscriptstyle S}}$ candidates that decay later, such that
track segments of the pions cannot be formed in the vertex detector, are
called _downstream_ candidates; these have a larger momentum resolution than
the long candidates, and thus the corresponding $\pi^{+}\pi^{-}$ pairs are
required to have an invariant mass within $\pm
55\text{\,}\mathrm{MeV}\text{/}{\mathrm{\mathit{c}}}^{2}$ of the known
${K^{0}_{\rm\scriptscriptstyle S}}$ mass. A good vertex fit quality and
sufficient separation from the $B^{0}$ decay vertex are required for the
${K^{0}_{\rm\scriptscriptstyle S}}$ candidate’s decay vertex. To eliminate
background contributions from
$\varLambda^{0}_{b}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}\varLambda$ decays, the $\pi^{+}$ ($\pi^{-}$) candidate has to fulfill
particle identification requirements if the invariant mass under a $p\pi^{-}$
($\pi^{+}\overline{p}$) mass hypothesis is compatible with the $\varLambda$
mass.

The $B^{0}$ candidates are reconstructed from
${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}$ and
${K^{0}_{\rm\scriptscriptstyle S}}$ candidates that form a good quality
vertex. Their decay time $t$ is obtained from a fit to the full decay chain
while constraining the production vertex of the $B^{0}$ to the associated PV
[20]. The reconstructed $B^{0}$ candidate mass $m$ is obtained from a similar
fit with the $\mu^{+}\mu^{-}$ and $\pi^{+}\pi^{-}$ invariant masses
constrained to the known ${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}$ and
${K^{0}_{\rm\scriptscriptstyle S}}$ masses. The latter fit must satisfy loose
requirements on its quality, and resulting candidates are only retained if
$5230<m<$5330\text{\,}\mathrm{MeV}\text{/}{\mathrm{\mathit{c}}}^{2}$$ and
$0.3<t<$18.3\text{\,}\mathrm{ps}$$. The fit uncertainty $\sigma_{t}$ on the
decay time is required to be smaller than $200\text{\,}\mathrm{fs}$, which is
well above the average resolution of $55\text{\,}\mathrm{fs}$
($65\text{\,}\mathrm{fs}$) for candidates with long (downstream)
${K^{0}_{\rm\scriptscriptstyle S}}$ daughters. The quantity $\sigma_{t}$ is
used later in the analysis as an estimate of the per-candidate decay-time
resolution. Multiple PVs and, in a small fraction of events, multiple
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ candidates, lead to multiple
($B^{0},\text{PV}$) pairs per event. In such cases, one pair is chosen at
random.

Various simulated data samples are used in the analysis. In the simulation,
$pp$ collisions are generated using Pythia [21, *Sjostrand:2007gs] with a
specific LHCb configuration [23]. Decays of hadronic particles are described
by EvtGen [24]. The interaction of the generated particles with the detector,
and its response, are implemented using the Geant4 toolkit [25,
*Agostinelli:2002hh] as described in Ref. [27].

Tagging algorithms are used to infer the initial flavor of the $B$ meson
candidate, i.e. whether it contained a $b$ or a $\overline{b}$ quark at
production. Each algorithm provides a decision $d$ on the flavor of the $B$
meson candidate (tag), and an estimate $\eta$ of the probability for that
decision to be incorrect (mistag probability). The knowledge of the $B$ meson
production flavor is essential for this analysis, and so only candidates for
which the tagging algorithms yield a decision are considered.

One class of flavor tagging algorithms, the opposite-side tagger (OS),
exploits the dominant production mechanism of $b$ hadrons, i.e. the production
of $b\overline{b}$ quark pairs, by reconstructing the $b$ hadron produced in
association with the signal $B$ meson. The OS tagger uses the charge of the
electron or muon from semileptonic $b$ decays, the charge of the kaon from the
$b\\!\rightarrow c\\!\rightarrow s$ decay chain, and the inclusive charge of
particles associated with the secondary vertex reconstructed from the $b$
hadron decay products; further details are described in Ref. [28].

A major improvement in this analysis over Ref. [15] is the inclusion of the
same-side pion tagger (SS$\pi$), which deduces the production flavor by
exploiting pions produced in the fragmentation of the $b$ quark that produced
the signal $B$ meson or in the decay of excited $B$ mesons into the signal $B$
meson [29, 30]. Tagging pion candidates are selected requiring charged, high
momentum and high transverse-momentum particles that are consistent with
originating from the associated PV. Pions are identified using information
from the particle identification detectors, and the difference between the
invariant mass of the $B$ and the $B\pi^{\pm}$ pair is required to be less
than $1.2\text{\,}\mathrm{GeV}\text{/}{\mathrm{\mathit{c}}}^{2}$.
Additionally, the flight directions of the pion and the $B$ candidate must be
compatible. If multiple pion candidates pass the selection, the one with the
highest transverse momentum is used. The mistag probability is obtained using
a neural network which is trained on simulated events and whose inputs are
global event properties and kinematic and geometric information on the pion
and $B$ signal candidates.

The tagging calibration is performed in control samples of $B$ mesons whose
final state determines the $B$ flavor at decay time, by determining a linear
correction $\omega(\eta)$ that relates the estimated mistag probability $\eta$
with the mistag probability $\omega$ observed in the control sample. To
account for asymmetries in the detection efficiency of charged particles,
which can lead to different mistag probabilities for $B^{0}$ and ${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ mesons, an additional linear
correction function $\Delta\omega(\eta)$ is determined. Asymmetries in the
efficiency of the algorithms in determining a decision are found to be
negligible.

The $B^{+}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}K^{+}$
decay is used to determine the flavor tagging calibration for the OS tagger. A
consistency check of the calibration is performed in a control sample of
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}K^{*0}$
decays, showing a good correspondence of the calibration between $B{}^{+}$ and
$B{}^{0}$ decays. As the quarks that accompany the $b$ quark in $B^{+}$ and
$B^{0}$ mesons differ, the SS$\pi$ tagger calibration is performed with
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}K^{*0}$ decays
[31]. Systematic uncertainties are assigned for the uncertainties associated
with the calibration method and for the validity of the calibration in the
signal decay mode. A summary of the calibration results is given in the
Appendix.

The effective tagging efficiency is the product of the probability for
reaching a tagging decision, $\varepsilon_{\text{tag}}=$36.54\,\pm
0.14\text{\,}\mathrm{\char 37\relax}$$, and the square of the effective
dilution, $D\equiv 1-2\omega=$28.75\,\pm 0.24\text{\,}\mathrm{\char
37\relax}$$, which corresponds to an effective mistag probability of
$\omega=$35.62\,\pm 0.12\text{\,}\mathrm{\char 37\relax}$$. Compared to the
previous LHCb analysis [15] the effective tagging efficiency
$\varepsilon_{\text{eff}}=\varepsilon_{\text{tag}}D^{2}$ increases from
$2.38\text{\,}\mathrm{\char 37\relax}$ to $3.02\text{\,}\mathrm{\char
37\relax}$, mainly due to the inclusion of the SS$\pi$ tagger.

The values of the $C\\!P$ violation observables $S$ and $C$ are estimated by
maximizing the likelihood of a probability density function (PDF) describing
the unbinned distributions of the following observables: the reconstructed
mass $m$, the decay time $t$ and its uncertainty estimate $\sigma_{t}$, the OS
and SS$\pi$ flavor tag decisions $d_{\text{OS}}$ and $d_{\text{SS}\pi}$, and
the corresponding per-candidate mistag probability estimates
$\eta_{\text{OS}}$ and $\eta_{\text{SS}\pi}$. The fit is performed
simultaneously in $24$ independent subsamples, chosen according to data-taking
conditions ($7\text{\,}\mathrm{TeV}$, $8\text{\,}\mathrm{TeV}$),
${K^{0}_{\rm\scriptscriptstyle S}}$ type (downstream, long), flavor tagging
algorithm (OS only, SS$\pi$ only, OS and SS$\pi$), and two trigger
requirements. In each category the data distribution is modeled using a sum of
two individual PDFs, one for the $B^{0}$ signal and one for the combinatorial
background.

The reconstructed mass of the signal component is parametrized with a double-
sided Hypatia PDF [32] with tail parameters determined from simulation. An
exponential function is used to model the background component, with
independent parameters for the downstream and long
${K^{0}_{\rm\scriptscriptstyle S}}$ subsamples. The fit to the mass
distributions yields $41\,560\,\pm 270$ tagged
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ signal decays. The mass distribution
and projections of the PDFs are shown in Fig. 1 (a).

Figure 1:  Distribution of (a) the reconstructed mass and (b) logarithmic
distribution of the decay time of tagged
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ candidates. The solid black lines
show the fit projections, while the dashed (dotted) lines show the projections
for the signal (background) components only.

The decay-time resolution is modeled by a sum of three Gaussian functions with
common mean, but different widths, which are convolved with the PDFs
describing the decay-time distributions. Two of the widths are given by the
per-candidate resolution estimate $\sigma_{t}$, each calibrated with
independent linear calibration functions. The third Gaussian describes the
resolution for candidates associated to a wrong PV. The scale and width
parameters are obtained in a fit to the decay-time distribution of a control
sample of $B^{0}$ candidates formed from prompt
${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}$ and
${K^{0}_{\rm\scriptscriptstyle S}}$ mesons. The parameters are determined
separately for candidates formed from downstream and long
${K^{0}_{\rm\scriptscriptstyle S}}$ candidates.

Trigger, reconstruction, and selection criteria distort the measured $B^{0}$
decay-time distribution, leading to a decay-time dependent efficiency. Effects
of the trigger requirements, which distort the decay-time distribution at low
decay times, are determined using data. The misreconstruction of tracks leads
to inefficiencies at large decay times. To account for this effect, an
additional decay-time dependent efficiency of the form $e^{-\beta_{t}t}$ is
used, where $\beta_{t}$ is obtained from simulation.

The PDF of true decay times $t^{\prime}$ is given by

$\displaystyle\mathcal{P}\left(t^{\prime},d_{\text{OS}},d_{\text{SS}\pi}|\eta_{\text{OS}},\eta_{\text{SS}\pi}\right)$
(2)
$\displaystyle=\sum_{d^{\prime}}\left[\prod_{j}\zeta(d_{j},\eta_{j},d^{\prime})\right](1-d^{\prime}A_{\text{P}})\,e^{-t^{\prime}/\tau}\left\\{1-d^{\prime}S\sin(\mathrm{\Delta}mt^{\prime})+d^{\prime}C\cos(\mathrm{\Delta}mt^{\prime})\right\\},$

where the tag decision $d$ takes the value $+1$ ($-1$) for a tagged $B^{0}$
(${\kern 1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$) candidate and
$d^{\prime}$ takes the value $+1$ ($-1$) for the $B^{0}$ (${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$) component of the signal
distribution, $\tau$ is the $B^{0}$ meson lifetime, and

$\zeta(d_{j},\eta_{j},d^{\prime})=1+d_{j}\left(1-2\left[\omega(\eta_{j})+d^{\prime}\frac{\Delta\omega(\eta_{j})}{2}\right]\right)$
(3)

represents the calibration of the tagging response from the tagging algorithm
$j=\\{\text{OS},\text{SS}\pi\\}$. The production asymmetry
$A_{\text{P}}\equiv{[\sigma({{\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}})-\sigma({B^{0}})]}/{[\sigma({{\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}})+\sigma({B^{0}})]}$, where
$\sigma$ denotes the production cross-section inside the LHCb acceptance, is
obtained using a measurement in $7\text{\,}\mathrm{TeV}$ $pp$ collisions [33].
Considering differences between the $7$ and $8\text{\,}\mathrm{TeV}$ data-
taking conditions, the production asymmetries are determined as
$A_{\text{P}}^{$7\text{\,}\mathrm{TeV}$}=$-0.0108\pm 0.0052\,\text{(stat)}\pm
0.0014\,\text{(syst)}$$ and
$A_{\text{P}}^{$8\text{\,}\mathrm{TeV}$}=A_{\text{P}}^{$7\text{\,}\mathrm{TeV}$}+\Delta
A_{\text{P}}$ with $\Delta A_{\text{P}}=$0.0004\pm 0.0018\,\text{(syst)}$$
[34]. The background decay-time distribution is parametrized by a sum of
exponential functions, convolved with the resolution model used for the
signal. This parametrization does not depend on the tag decision and mistag
probability estimates. The number of required exponential functions varies
across subsamples. The decay-time distribution and projections of the PDFs are
shown in Fig. 1 (b). The distributions of the per-candidate resolution
estimate $\sigma_{t}$ and the per-candidate mistag probabilities,
$\eta_{\text{OS}}$ and $\eta_{\text{SS}\pi}$, are modeled by empirical
functions. Independent parameterizations are chosen for the signal and
background components.

The likelihood is a function of $83$ free parameters, including $S$ and $C$,
and $48$ yield parameters for the signal and the background components in $24$
individual subsamples. Eleven parameters are external inputs, including the
production asymmetry, the flavor tagging calibration parameters, and the mass
difference $\mathrm{\Delta}m$ [19]. These are constrained in the fit within
their statistical uncertainties and taking their correlations into account.
The likelihood fit yields $S=$0.729\pm 0.035$$ and $C=$-0.033\pm 0.032$$ with
a correlation coefficient of $\rho(S,C)=$0.483$$. Fig. 2 shows the decay-time
dependent signal-yield asymmetry. An additional fit with fixed $C=$0$$ yields
$S=$0.746\,\pm 0.030$$. Corrections of $+0.002$ for $S$ and $-0.005$ for $C$
are applied to account for $C\\!P$ violation in $K^{0}$–${\kern
1.99997pt\overline{\kern-1.99997ptK}}{}^{0}$ mixing and for the difference in
the nuclear cross-sections in material between $K^{0}$ and ${\kern
1.99997pt\overline{\kern-1.99997ptK}}{}^{0}$ states [35, *Ko:2010mk]. The
correction is negligible for the result for $S$ with $C=0$.

Figure 2:  Time-dependent signal-yield asymmetry $(N_{{\kern
1.25995pt\overline{\kern-1.25995ptB}}{}^{0}}-N_{B^{0}})/(N_{{\kern
1.25995pt\overline{\kern-1.25995ptB}}{}^{0}}+N_{B^{0}})$. Here, $N_{B^{0}}$
($N_{{\kern 1.25995pt\overline{\kern-1.25995ptB}}{}^{0}}$) is the number of
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ decays with a $B^{0}$ (${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$) flavor tag. The data points are
obtained with the sPlot technique [37], assigning signal weights to the events
based on a fit to the reconstructed mass distribution. The solid curve is the
projection of the signal PDF.

Various sources of systematic uncertainties on the $C\\!P$ observables are
examined, in particular from mismodeling PDFs and from systematic
uncertainties on the input parameters. In each study, a large set of
pseudoexperiments is simulated using a PDF modified such as to include the
systematic effect of interest; the relevant distributions from these
pseudoexperiments are then fitted with the nominal PDF. Significant average
deviations of the fit results from the input values are used as estimates of
systematic uncertainties. The largest systematic uncertainty on $S$, $\pm
0.018$, accounts for possible tag asymmetries in the background; for $C$ the
largest uncertainty, $\pm 0.0034$, results from the systematic uncertainty on
$\mathrm{\Delta}m$. Systematic uncertainties on the flavor tagging calibration
account for the second largest systematic uncertainty on $S$, $\pm 0.006$, and
on $C$, $\pm 0.0024$. The third largest uncertainty on $S$, $\pm 0.005$,
arises from assuming $\mathrm{\Delta}\Gamma=0$ and is evaluated by generating
pseudoexperiments with $\mathrm{\Delta}\Gamma$ set to the value of its current
uncertainty, $0.007\text{\,}{\mathrm{ps}}^{-1}$ [9], and then neglecting it in
the fit. Remaining uncertainties due to neglecting correlations between the
reconstructed mass and decay time of the candidates, mismodeling of the decay-
time resolution and efficiency, the systematic uncertainty of the production
asymmetry, and the uncertainty on the length scale of the vertex detector are
small and are given in the Appendix. Adding all contributions in quadrature
results in total systematic uncertainties of $\pm 0.020$ on $S$ and $\pm
0.005$ on $C$.

Several consistency checks are performed by splitting the data set according
to different data-taking conditions, tagging algorithms, and different
reconstruction and trigger requirements. All results show good agreement with
the nominal results.

In conclusion, a measurement of $C\\!P$ violation in the interference between
the direct decay and the decay after $B^{0}$–${\kern
1.79993pt\overline{\kern-1.79993ptB}}{}^{0}$ oscillation to a
${J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}{K^{0}_{\rm\scriptscriptstyle
S}}$ final state is performed using $41\,500$ flavor-tagged
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ decays reconstructed with the LHCb
detector in a sample of proton-proton collisions at center-of-mass energies of
$7$ and $8\text{\,}\mathrm{TeV}$, corresponding to an integrated luminosity of
$3.0\text{\,}{\mathrm{fb}}^{-1}$. The $C\\!P$ observables $S$ and $C$, which
allow the determination of the CKM angle $\beta$, are measured to be

$\displaystyle S$ $\displaystyle=\phantom{+}0.731\pm 0.035\,\text{(stat)}\pm
0.020\,\text{(syst)},$ $\displaystyle C$ $\displaystyle=-0.038\pm
0.032\,\text{(stat)}\pm 0.005\,\text{(syst)},$

with a statistical correlation coefficient $\rho(S,C)=0.483$. When $C$ is
fixed to zero the measurement yields $S=\sin(2\beta)=$0.746\,\pm
0.030$\,\text{(stat)}$. This measurement supersedes the previous LHCb result
obtained with $1.0\text{\,}{\mathrm{fb}}^{-1}$ [15], and represents the most
precise time-dependent $C\\!P$ violation measurement at a hadron collider to
date. Furthermore, the result has a similar precision to, and is in good
agreement with, previous measurements performed at the Belle and BaBar
experiments at the KEKB and PEP-II colliders [3, 4]. This result is in
excellent agreement with the expectations from other measurements and improves
the consistency of the CKM sector of the Standard Model.

## 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); 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).

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Appendix

### Overview of tagging calibration parameters

The calibration functions of the mistag probability $\omega(\eta)$ and the
mistag probability difference
$\Delta\omega(\eta)=\omega^{B^{0}}-\omega^{{\kern
1.25995pt\overline{\kern-1.25995ptB}}{}^{0}}$ are chosen as

$\omega(\eta)=p_{1}(\eta-\langle\eta\rangle)+p_{0},\qquad\Delta\omega(\eta)=\Delta
p_{1}(\eta-\langle\eta\rangle)+\Delta p_{0}\ .$ (A1)

The OS calibration parameters are determined to be

$\begin{split}p_{0}^{\text{OS}}&=0.3815\phantom{}\pm
0.0011\phantom{}\text{\,(stat)}\pm 0.0016\phantom{}\text{\,(syst)}\ ,\\\
p_{1}^{\text{OS}}&=0.978\phantom{0}\pm 0.012\phantom{0}\text{\,(stat)}\pm
0.009\phantom{0}\text{\,(syst)}\ ,\\\ \Delta
p_{0}^{\text{OS}}&=0.0148\phantom{}\pm 0.0016\phantom{}\text{\,(stat)}\pm
0.0008\phantom{}\text{\,(syst)}\ ,\\\ \Delta
p_{1}^{\text{OS}}&=0.070\phantom{0}\pm 0.018\phantom{0}\text{\,(stat)}\pm
0.004\phantom{0}\text{\,(syst)}\ ,\\\ \langle\eta^{\text{OS}}\rangle&=0.3786\
.\\\ \end{split}$ (A2)

Fig. A1 shows the raw mixing asymmetry and the calibration of the mistag
estimates. The measured SS$\pi$ calibration parameters are

$\begin{split}p_{0}^{\text{SS}\pi}&=\phantom{-}0.4232\phantom{}\pm
0.0029\phantom{}\text{\,(stat)}\pm 0.0028\phantom{}\text{\,(syst)}\ ,\\\
p_{1}^{\text{SS}\pi}&=\phantom{-}1.011\phantom{0}\pm
0.064\phantom{0}\text{\,(stat)}\pm 0.031\phantom{0}\text{\,(syst)}\ ,\\\
\Delta p_{0}^{\text{SS}\pi}&=-0.0026\phantom{}\pm
0.0043\phantom{}\text{\,(stat)}\pm 0.0027\phantom{}\text{\,(syst)}\ ,\\\
\Delta p_{1}^{\text{SS}\pi}&=-0.171\phantom{0}\pm
0.096\phantom{0}\text{\,(stat)}\pm 0.04\phantom{00}\text{\,(syst)}\ ,\\\
\langle\eta^{\text{SS}\pi}\rangle&=\phantom{-}0.425\ .\\\ \end{split}$ (A3)

Figure A1: (a) Raw mixing asymmetry
$(N_{\text{unmixed}}-N_{\text{mixed}})/(N_{\text{unmixed}}+N_{\text{mixed}})$
for all SS$\pi$ tagged
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}K^{*0}$ decay
candidates. Here, $N_{\text{unmixed}}$ ($N_{\text{mixed}}$) is the number of
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}K^{*0}$ decays
with a final state that does (not) correspond to the flavor tag. The black
line shows the fit projection. (b) The linear calibration of the SS$\pi$
mistag probability with
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip 2.0mu}K^{*0}$
decays.

In the dataset of 114000
$B^{0}\\!\rightarrow{J\mskip-3.0mu/\mskip-2.0mu\psi\mskip
2.0mu}{K^{0}_{\rm\scriptscriptstyle S}}$ decays, the OS tagger algorithm
yields a tagging power of $(2.63\pm 0.04)\%$ and the SS$\pi$ tagger algorithm
yields $(0.376\pm 0.024)\%$. For events that have both OS and SS$\pi$ tagging
decisions, the effective tagging power is $(0.503\pm 0.010)\%$. The combined
effective tagging power of these three overlapping tagging categories is
$(3.02\pm 0.05)\%$.

### Summary of systematic uncertainties

The systematic uncertainties are summarised in Table A1. The overall
systematic uncertainty is calculated by summing the single uncertainties in
quadrature. The relative systematic uncertainties compared to the central
values of $S$ and $C$ are given in brackets. Here, we set $S=$0.729$$ and
$C=$-0.033$$ as reference.

Table A1: Systematic uncertainties $\sigma_{S}$ and $\sigma_{C}$ on $S$ and
$C$. Entries marked with a dash represent studies where no significant effect
is observed.

Origin | $\sigma_{S}$ | $\sigma_{C}$
---|---|---
Background tagging asymmetry | $0.0179$ | ($2.5$$\mathrm{\char 37\relax}$) | $0.0015$ | ($4.5$$\mathrm{\char 37\relax}$)
Tagging calibration | $0.0062$ | ($0.9$$\mathrm{\char 37\relax}$) | $0.0024$ | ($7.2$$\mathrm{\char 37\relax}$)
$\Delta\Gamma$ | $0.0047$ | ($0.6$$\mathrm{\char 37\relax}$) | —
Fraction of wrong PV component | $0.0021$ | ($0.3$$\mathrm{\char 37\relax}$) | $0.0011$ | ($3.3$$\mathrm{\char 37\relax}$)
$z$-scale | $0.0012$ | ($0.2$$\mathrm{\char 37\relax}$) | $0.0023$ | ($7.0$$\mathrm{\char 37\relax}$)
$\mathrm{\Delta}m$ | — | $0.0034$ | ($10.3$$\mathrm{\char 37\relax}$)
Upper decay time acceptance | — | $0.0012$ | ($3.6$$\mathrm{\char 37\relax}$)
Correlation between mass and decay time | — | —
Decay time resolution calibration | — | —
Decay time resolution offset | — | —
Low decay time acceptance | — | —
Production asymmetry | — | —
Sum | $0.020$ | ($2.7$$\mathrm{\char 37\relax}$) | $0.005$ | ($15.2$$\mathrm{\char 37\relax}$)

LHCb collaboration

R. Aaij41, B. Adeva37, M. Adinolfi46, A. Affolder52, Z. Ajaltouni5, S. Akar6,
J. Albrecht9, F. Alessio38, M. Alexander51, S. Ali41, G. Alkhazov30, P.
Alvarez Cartelle53, A.A. Alves Jr57, S. Amato2, S. Amerio22, Y. Amhis7, L.
An3, L. Anderlini17,g, J. Anderson40, M. Andreotti16,f, J.E. Andrews58, R.B.
Appleby54, O. Aquines Gutierrez10, F. Archilli38, A. Artamonov35, M. Artuso59,
E. Aslanides6, G. Auriemma25,n, M. Baalouch5, S. Bachmann11, J.J. Back48, A.
Badalov36, C. Baesso60, W. Baldini16,38, R.J. Barlow54, C. Barschel38, S.
Barsuk7, W. Barter38, V. Batozskaya28, V. Battista39, A. Bay39, L. Beaucourt4,
J. Beddow51, F. Bedeschi23, I. Bediaga1, L.J. Bel41, I. Belyaev31, E. Ben-
Haim8, G. Bencivenni18, S. Benson38, J. Benton46, A. Berezhnoy32, R. Bernet40,
A. Bertolin22, M.-O. Bettler38, M. van Beuzekom41, A. Bien11, S. Bifani45, T.
Bird54, A. Birnkraut9, A. Bizzeti17,i, T. Blake48, F. Blanc39, J. Blouw10, S.
Blusk59, V. Bocci25, A. Bondar34, N. Bondar30,38, W. Bonivento15, S. Borghi54,
A. Borgia59, M. Borsato7, T.J.V. Bowcock52, E. Bowen40, C. Bozzi16, S.
Braun11, D. Brett54, M. Britsch10, T. Britton59, J. Brodzicka54, N.H. Brook46,
A. Bursche40, J. Buytaert38, S. Cadeddu15, R. Calabrese16,f, M. Calvi20,k, M.
Calvo Gomez36,p, P. Campana18, D. Campora Perez38, L. Capriotti54, A.
Carbone14,d, G. Carboni24,l, R. Cardinale19,j, A. Cardini15, P. Carniti20, L.
Carson50, K. Carvalho Akiba2,38, R. Casanova Mohr36, G. Casse52, L.
Cassina20,k, L. Castillo Garcia38, M. Cattaneo38, Ch. Cauet9, G. Cavallero19,
R. Cenci23,t, M. Charles8, Ph. Charpentier38, M. Chefdeville4, S. Chen54,
S.-F. Cheung55, N. Chiapolini40, M. Chrzaszcz40,26, X. Cid Vidal38, G.
Ciezarek41, P.E.L. Clarke50, M. Clemencic38, H.V. Cliff47, J. Closier38, V.
Coco38, J. Cogan6, E. Cogneras5, V. Cogoni15,e, L. Cojocariu29, G.
Collazuol22, P. Collins38, A. Comerma-Montells11, A. Contu15,38, A. Cook46, M.
Coombes46, S. Coquereau8, G. Corti38, M. Corvo16,f, I. Counts56, B.
Couturier38, G.A. Cowan50, D.C. Craik48, A.C. Crocombe48, M. Cruz Torres60, S.
Cunliffe53, R. Currie53, C. D’Ambrosio38, J. Dalseno46, P.N.Y. David41, A.
Davis57, K. De Bruyn41, S. De Capua54, M. De Cian11, J.M. De Miranda1, L. De
Paula2, W. De Silva57, P. De Simone18, C.-T. Dean51, D. Decamp4, M.
Deckenhoff9, L. Del Buono8, N. Déléage4, D. Derkach55, O. Deschamps5, F.
Dettori38, B. Dey40, A. Di Canto38, F. Di Ruscio24, H. Dijkstra38, S.
Donleavy52, F. Dordei11, M. Dorigo39, A. Dosil Suárez37, D. Dossett48, A.
Dovbnya43, K. Dreimanis52, G. Dujany54, F. Dupertuis39, P. Durante38, R.
Dzhelyadin35, A. Dziurda26, A. Dzyuba30, S. Easo49,38, U. Egede53, V.
Egorychev31, S. Eidelman34, S. Eisenhardt50, U. Eitschberger9, R. Ekelhof9, L.
Eklund51, I. El Rifai5, Ch. Elsasser40, S. Ely59, S. Esen11, H.M. Evans47, T.
Evans55, A. Falabella14, C. Färber11, C. Farinelli41, N. Farley45, S. Farry52,
R. Fay52, D. Ferguson50, V. Fernandez Albor37, F. Ferrari14, F. Ferreira
Rodrigues1, M. Ferro-Luzzi38, S. Filippov33, M. Fiore16,38,f, M. Fiorini16,f,
M. Firlej27, C. Fitzpatrick39, T. Fiutowski27, P. Fol53, M. Fontana10, F.
Fontanelli19,j, R. Forty38, O. Francisco2, M. Frank38, C. Frei38, M.
Frosini17, J. Fu21,38, E. Furfaro24,l, A. Gallas Torreira37, D. Galli14,d, S.
Gallorini22,38, S. Gambetta19,j, M. Gandelman2, P. Gandini55, Y. Gao3, J.
García Pardiñas37, J. Garofoli59, J. Garra Tico47, L. Garrido36, D. Gascon36,
C. Gaspar38, U. Gastaldi16, R. Gauld55, L. Gavardi9, G. Gazzoni5, A.
Geraci21,v, D. Gerick11, E. Gersabeck11, M. Gersabeck54, T. Gershon48, Ph.
Ghez4, A. Gianelle22, S. Gianì39, V. Gibson47, L. Giubega29, V.V. Gligorov38,
C. Göbel60, D. Golubkov31, A. Golutvin53,31,38, A. Gomes1,a, C. Gotti20,k, M.
Grabalosa Gándara5, R. Graciani Diaz36, L.A. Granado Cardoso38, E. Graugés36,
E. Graverini40, G. Graziani17, A. Grecu29, E. Greening55, S. Gregson47, P.
Griffith45, L. Grillo11, O. Grünberg63, E. Gushchin33, Yu. Guz35,38, T. Gys38,
C. Hadjivasiliou59, G. Haefeli39, C. Haen38, S.C. Haines47, S. Hall53, B.
Hamilton58, T. Hampson46, X. Han11, S. Hansmann-Menzemer11, N. Harnew55, S.T.
Harnew46, J. Harrison54, J. He38, T. Head39, V. Heijne41, K. Hennessy52, P.
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Hicheur2, D. Hill55, M. Hoballah5, C. Hombach54, W. Hulsbergen41, T. Humair53,
N. Hussain55, D. Hutchcroft52, D. Hynds51, M. Idzik27, P. Ilten56, R.
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I. Komarov39, R.F. Koopman42, P. Koppenburg41,38, M. Korolev32, L. Kravchuk33,
K. Kreplin11, M. Kreps48, G. Krocker11, P. Krokovny34, F. Kruse9, W.
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F. Lionetto40, B. Liu15, S. Lohn38, I. Longstaff51, J.H. Lopes2, P. Lowdon40,
D. Lucchesi22,r, H. Luo50, A. Lupato22, E. Luppi16,f, O. Lupton55, F.
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Matev38, Z. Mathe38, C. Matteuzzi20, A. Mauri40, B. Maurin39, A. Mazurov45, M.
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Pilař48, D. Pinci25, A. Pistone19, S. Playfer50, M. Plo Casasus37, T.
Poikela38, F. Polci8, A. Poluektov48,34, I. Polyakov31, E. Polycarpo2, A.
Popov35, D. Popov10, B. Popovici29, C. Potterat2, E. Price46, J.D. Price52, J.
Prisciandaro39, A. Pritchard52, C. Prouve46, V. Pugatch44, A. Puig Navarro39,
G. Punzi23,s, W. Qian4, R. Quagliani7,46, B. Rachwal26, J.H. Rademacker46, B.
Rakotomiaramanana39, M. Rama23, M.S. Rangel2, I. Raniuk43, N. Rauschmayr38, G.
Raven42, F. Redi53, S. Reichert54, M.M. Reid48, A.C. dos Reis1, S.
Ricciardi49, S. Richards46, M. Rihl38, K. Rinnert52, V. Rives Molina36, P.
Robbe7,38, A.B. Rodrigues1, E. Rodrigues54, J.A. Rodriguez Lopez62, P.
Rodriguez Perez54, S. Roiser38, V. Romanovsky35, A. Romero Vidal37, M.
Rotondo22, J. Rouvinet39, T. Ruf38, H. Ruiz36, P. Ruiz Valls66, J.J. Saborido
Silva37, N. Sagidova30, P. Sail51, B. Saitta15,e, V. Salustino Guimaraes2, C.
Sanchez Mayordomo66, B. Sanmartin Sedes37, R. Santacesaria25, C. Santamarina
Rios37, E. Santovetti24,l, A. Sarti18,m, C. Satriano25,n, A. Satta24, D.M.
Saunders46, D. Savrina31,32, M. Schellenberg9, M. Schiller38, H. Schindler38,
M. Schlupp9, M. Schmelling10, B. Schmidt38, O. Schneider39, A. Schopper38,
M.-H. Schune7, R. Schwemmer38, B. Sciascia18, A. Sciubba25,m, A. Semennikov31,
I. Sepp53, N. Serra40, J. Serrano6, L. Sestini22, P. Seyfert11, M. Shapkin35,
I. Shapoval16,43,f, Y. Shcheglov30, T. Shears52, L. Shekhtman34, V.
Shevchenko64, A. Shires9, R. Silva Coutinho48, G. Simi22, M. Sirendi47, N.
Skidmore46, I. Skillicorn51, T. Skwarnicki59, N.A. Smith52, E. Smith55,49, E.
Smith53, J. Smith47, M. Smith54, H. Snoek41, M.D. Sokoloff57,38, F.J.P.
Soler51, F. Soomro39, D. Souza46, B. Souza De Paula2, B. Spaan9, P.
Spradlin51, S. Sridharan38, F. Stagni38, M. Stahl11, S. Stahl38, O.
Steinkamp40, O. Stenyakin35, F. Sterpka59, S. Stevenson55, S. Stoica29, S.
Stone59, B. Storaci40, S. Stracka23,t, M. Straticiuc29, U. Straumann40, R.
Stroili22, L. Sun57, W. Sutcliffe53, K. Swientek27, S. Swientek9, V.
Syropoulos42, M. Szczekowski28, P. Szczypka39,38, T. Szumlak27, S. T’Jampens4,
M. Teklishyn7, G. Tellarini16,f, F. Teubert38, C. Thomas55, E. Thomas38, J.
van Tilburg41, V. Tisserand4, M. Tobin39, J. Todd57, S. Tolk42, L.
Tomassetti16,f, D. Tonelli38, S. Topp-Joergensen55, N. Torr55, E. Tournefier4,
S. Tourneur39, K. Trabelsi39, M.T. Tran39, M. Tresch40, A. Trisovic38, A.
Tsaregorodtsev6, P. Tsopelas41, N. Tuning41,38, M. Ubeda Garcia38, A.
Ukleja28, A. Ustyuzhanin65, U. Uwer11, C. Vacca15,e, V. Vagnoni14, G.
Valenti14, A. Vallier7, R. Vazquez Gomez18, P. Vazquez Regueiro37, C. Vázquez
Sierra37, S. Vecchi16, J.J. Velthuis46, M. Veltri17,h, G. Veneziano39, M.
Vesterinen11, J.V. Viana Barbosa38, B. Viaud7, D. Vieira2, M. Vieites Diaz37,
X. Vilasis-Cardona36,p, A. Vollhardt40, D. Volyanskyy10, D. Voong46, A.
Vorobyev30, V. Vorobyev34, C. Voß63, J.A. de Vries41, R. Waldi63, C.
Wallace48, R. Wallace12, J. Walsh23, S. Wandernoth11, J. Wang59, D.R. Ward47,
N.K. Watson45, D. Websdale53, A. Weiden40, M. Whitehead48, D. Wiedner11, G.
Wilkinson55,38, M. Wilkinson59, M. Williams38, M.P. Williams45, M. Williams56,
F.F. Wilson49, J. Wimberley58, J. Wishahi9, W. Wislicki28, M. Witek26, G.
Wormser7, S.A. Wotton47, S. Wright47, K. Wyllie38, Y. Xie61, Z. Xu39, Z.
Yang3, X. Yuan34, O. Yushchenko35, M. Zangoli14, M. Zavertyaev10,b, L. Zhang3,
Y. Zhang3, A. Zhelezov11, A. Zhokhov31, L. Zhong3.

1Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
2Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
3Center for High Energy Physics, Tsinghua University, Beijing, China
4LAPP, Université Savoie Mont-Blanc, CNRS/IN2P3, Annecy-Le-Vieux, France
5Clermont Université, Université Blaise Pascal, CNRS/IN2P3, LPC, Clermont-
Ferrand, France
6CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France
7LAL, Université Paris-Sud, CNRS/IN2P3, Orsay, France
8LPNHE, Université Pierre et Marie Curie, Université Paris Diderot,
CNRS/IN2P3, Paris, France
9Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
10Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
11Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg,
Germany
12School of Physics, University College Dublin, Dublin, Ireland
13Sezione INFN di Bari, Bari, Italy
14Sezione INFN di Bologna, Bologna, Italy
15Sezione INFN di Cagliari, Cagliari, Italy
16Sezione INFN di Ferrara, Ferrara, Italy
17Sezione INFN di Firenze, Firenze, Italy
18Laboratori Nazionali dell’INFN di Frascati, Frascati, Italy
19Sezione INFN di Genova, Genova, Italy
20Sezione INFN di Milano Bicocca, Milano, Italy
21Sezione INFN di Milano, Milano, Italy
22Sezione INFN di Padova, Padova, Italy
23Sezione INFN di Pisa, Pisa, Italy
24Sezione INFN di Roma Tor Vergata, Roma, Italy
25Sezione INFN di Roma La Sapienza, Roma, Italy
26Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of
Sciences, Kraków, Poland
27AGH - University of Science and Technology, Faculty of Physics and Applied
Computer Science, Kraków, Poland
28National Center for Nuclear Research (NCBJ), Warsaw, Poland
29Horia Hulubei National Institute of Physics and Nuclear Engineering,
Bucharest-Magurele, Romania
30Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia
31Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia
32Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow,
Russia
33Institute for Nuclear Research of the Russian Academy of Sciences (INR RAN),
Moscow, Russia
34Budker Institute of Nuclear Physics (SB RAS) and Novosibirsk State
University, Novosibirsk, Russia
35Institute for High Energy Physics (IHEP), Protvino, Russia
36Universitat de Barcelona, Barcelona, Spain
37Universidad de Santiago de Compostela, Santiago de Compostela, Spain
38European Organization for Nuclear Research (CERN), Geneva, Switzerland
39Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
40Physik-Institut, Universität Zürich, Zürich, Switzerland
41Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands
42Nikhef National Institute for Subatomic Physics and VU University Amsterdam,
Amsterdam, The Netherlands
43NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
44Institute for Nuclear Research of the National Academy of Sciences (KINR),
Kyiv, Ukraine
45University of Birmingham, Birmingham, United Kingdom
46H.H. Wills Physics Laboratory, University of Bristol, Bristol, United
Kingdom
47Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
48Department of Physics, University of Warwick, Coventry, United Kingdom
49STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
50School of Physics and Astronomy, University of Edinburgh, Edinburgh, United
Kingdom
51School of Physics and Astronomy, University of Glasgow, Glasgow, United
Kingdom
52Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom
53Imperial College London, London, United Kingdom
54School of Physics and Astronomy, University of Manchester, Manchester,
United Kingdom
55Department of Physics, University of Oxford, Oxford, United Kingdom
56Massachusetts Institute of Technology, Cambridge, MA, United States
57University of Cincinnati, Cincinnati, OH, United States
58University of Maryland, College Park, MD, United States
59Syracuse University, Syracuse, NY, United States
60Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de
Janeiro, Brazil, associated to 2
61Institute of Particle Physics, Central China Normal University, Wuhan,
Hubei, China, associated to 3
62Departamento de Fisica , Universidad Nacional de Colombia, Bogota, Colombia,
associated to 8
63Institut für Physik, Universität Rostock, Rostock, Germany, associated to 11
64National Research Centre Kurchatov Institute, Moscow, Russia, associated to
31
65Yandex School of Data Analysis, Moscow, Russia, associated to 31
66Instituto de Fisica Corpuscular (IFIC), Universitat de Valencia-CSIC,
Valencia, Spain, associated to 36
67Van Swinderen Institute, University of Groningen, Groningen, The
Netherlands, associated to 41

aUniversidade Federal do Triângulo Mineiro (UFTM), Uberaba-MG, Brazil
bP.N. Lebedev Physical Institute, Russian Academy of Science (LPI RAS),
Moscow, Russia
cUniversità di Bari, Bari, Italy
dUniversità di Bologna, Bologna, Italy
eUniversità di Cagliari, Cagliari, Italy
fUniversità di Ferrara, Ferrara, Italy
gUniversità di Firenze, Firenze, Italy
hUniversità di Urbino, Urbino, Italy
iUniversità di Modena e Reggio Emilia, Modena, Italy
jUniversità di Genova, Genova, Italy
kUniversità di Milano Bicocca, Milano, Italy
lUniversità di Roma Tor Vergata, Roma, Italy
mUniversità di Roma La Sapienza, Roma, Italy
nUniversità della Basilicata, Potenza, Italy
oAGH - University of Science and Technology, Faculty of Computer Science,
Electronics and Telecommunications, Kraków, Poland
pLIFAELS, La Salle, Universitat Ramon Llull, Barcelona, Spain
qHanoi University of Science, Hanoi, Viet Nam
rUniversità di Padova, Padova, Italy
sUniversità di Pisa, Pisa, Italy
tScuola Normale Superiore, Pisa, Italy
uUniversità degli Studi di Milano, Milano, Italy
vPolitecnico di Milano, Milano, Italy