Phys. Rev. Lett. 114, 041601 (2015) The semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$ mixing, $a_{\rm
sl}^d$, is measured in proton-proton collision data, corresponding to an
integrated ...luminosity of 3.0 fb$^{-1}$, recorded by the LHCb experiment.
Semileptonic $B^0$ decays are reconstructed in the inclusive final states
$D^-\mu^+$ and $D^{*-}\mu^+$, where the $D^-$ meson decays into the
$K^+\pi^-\pi^-$ final state, and the $D^{*-}$ meson into the
$\overline{D}{}^0(\rightarrow K^+\pi^-)\pi^-$ final state. The asymmetry
between the numbers of $D^{(*)-}\mu^+$ and $D^{(*)+}\mu^-$ decays is measured
as a function of the decay time of the $B^0$ mesons. The $CP$ asymmetry is
measured to be $a_{\rm sl}^d = (-0.02 \pm 0.19 \pm 0.30)\%$, where the first
uncertainty is statistical and the second systematic. This is the most precise
measurement of $a_{\rm sl}^d$ to date and is consistent with the prediction
from the Standard Model.
Phys. Rev. Lett. 113, 211801 (2014) We present a measurement of the $CP$-violating weak mixing phase $\phi_s$
using the decay $\bar{B}^{0}_{s}\to D_{s}^{+}D_{s}^{-}$ in a data sample
corresponding to ...$3.0$ fb$^{-1}$ of integrated luminosity collected with the
LHCb detector in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. An
analysis of the time evolution of the system, which does not constrain
$|\lambda|=1$ to allow for the presence of $CP$ violation in decay, yields
$\phi_s = 0.02 \pm 0.17$ (stat) $\pm 0.02$ (syst) rad, $|\lambda| =
0.91^{+0.18}_{-0.15}$ (stat) $\pm0.02$ (syst). This result is consistent with
the Standard Model expectation.
Eur.Phys.J. C75 (2015) 7, 311 The production of the $\eta_c (1S)$ state in proton-proton collisions is
probed via its decay to the $p \bar{p}$ final state with the LHCb detector, in
the rapidity ...range $2.0 < y < 4.5$ and in the meson transverse-momentum range
$p_T > 6.5$ GeV/c. The cross-section for prompt production of $\eta_c (1S)$
mesons relative to the prompt $J/\psi$ cross-section is measured, for the first
time, to be $\sigma_{\eta_c (1S)}/\sigma_{J/\psi} = 1.74 \pm 0.29 \pm 0.28 \pm
0.18 _{B}$ at a centre-of-mass energy $\sqrt{s} = 7$ TeV using data
corresponding to an integrated luminosity of 0.7 fb$^{-1}$, and $\sigma_{\eta_c
(1S)}/\sigma_{J/\psi} = 1.60 \pm 0.29 \pm 0.25 \pm 0.17 _{B}$ at $\sqrt{s} = 8$
TeV using 2.0 fb$^{-1}$. The uncertainties quoted are, in order, statistical,
systematic, and that on the ratio of branching fractions of the $\eta_c (1S)$
and $J/\psi$ decays to the $p \bar{p}$ final state. In addition, the inclusive
branching fraction of $b$-hadron decays into $\eta_c (1S)$ mesons is measured,
for the first time, to be $B ( b \rightarrow \eta_c X ) = (4.88 \pm 0.64 \pm
0.29 \pm 0.67 _{B}) \times 10^{-3}$, where the third uncertainty includes also
the uncertainty on the $J/\psi$ inclusive branching fraction from $b$-hadron
decays. The difference between the $J/\psi$ and $\eta_c (1S)$ meson masses is
determined to be $114.7 \pm 1.5 \pm 0.1$ MeV/c$^2$.
JHEP 10(2014)088 The production of $\chi_b$ mesons in proton-proton collisions is studied
using a data sample collected by the LHCb detector, at centre-of-mass energies
of $\sqrt{s}=7$ and $8$ TeV ...and corresponding to an integrated luminosity of
3.0 fb$^{-1}$. The $\chi_b$ mesons are identified through their decays to
$\Upsilon(1S)\gamma$ and $\Upsilon(2S)\gamma$ using photons that converted to
$e^+e^-$ pairs in the detector. The relative prompt production rate of
$\chi_{b1}(1P)$ and $\chi_{b2}(1P)$ mesons is measured as a function of the
$\Upsilon(1S)$ transverse momentum in the $\chi_b$ rapidity range $2.0<y<4.5$.
A precise measurement of the $\chi_b(3P)$ mass is also performed. Assuming a
mass splitting between the $\chi_{b1}(3P)$ and the $\chi_{b2}(3P)$ states of
10.5 MeV/$c^2$, the measured mass of the $\chi_{b1}(3P)$ meson is $
m(\chi_{b1}(3P))= 10515.7^{+2.2}_{-3.9}(stat) ^{+1.5}_{-2.1}(syst) MeV/c^2.$
Prompt production of charmonium \(\chi_{c0}\), \(\chi_{c1}\) and \(\chi_{c2}\) mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of \(\sqrt{s}=7\)TeV. The ...\(\chi_{c}\) mesons are identified through their decay to \(J/\psi\gamma\), with \(J/\psi\to\mu^+\mu^-\) using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of \(1.0\mathrm{fb}^{-1}\) collected by the LHCb detector, is used to measure the relative prompt production rate of \(\chi_{c1}\) and \(\chi_{c2}\) in the rapidity range \(2.0<y<4.5\) as a function of the \(J/\psi\) transverse momentum from 3 to 20 GeV\(/c\). First evidence for \(\chi_{c0}\) meson production at a high-energy hadron collider is also presented.
Phys. Rev. D 90, 112004 (2014) The charmless three-body decay modes $B^{\pm} \rightarrow K^{\pm} \pi^{+}
\pi^{-}$, $B^{\pm} \rightarrow K^{\pm} K^{+} K^{-}$, $B^{\pm} \rightarrow
\pi^{\pm} K^{+} ...K^{-}$ and $B^{\pm} \rightarrow \pi^{\pm} \pi^{+} \pi^{-}$ are
reconstructed using data, corresponding to an integrated luminosity of
3.0\;$\mbox{\,fb}^{-1}$, collected by the LHCb detector. The inclusive $C\!P$
asymmetries of these modes are measured to be $$ A_{C\!P}(B^{\pm} \rightarrow
K^{\pm} \pi^{+} \pi^{-})= +0.025 \pm 0.004 \pm 0.004 \pm 0.007 \\
A_{C\!P}(B^{\pm} \rightarrow K^{\pm} K^{+} K^{-}) = -0.036 \pm 0.004 \pm 0.002
\pm 0.007 \\ A_{C\!P}(B^{\pm} \rightarrow \pi^{\pm} \pi^{+} \pi^{-})= +0.058
\pm 0.008 \pm 0.009 \pm 0.007 \\ A_{C\!P}(B^{\pm} \rightarrow \pi^{\pm} K^{+}
K^{-})= -0.123 \pm 0.017 \pm 0.012 \pm 0.007 $$ %% where the first uncertainty
is statistical, the second systematic, and the third is due to the $C\!P$
asymmetry of the $B^{\pm} \rightarrow J/\psi K^{\pm}$ reference mode. The
distributions of these asymmetries are also studied as functions of position in
the Dalitz plot and suggest contributions from rescattering and resonance
interference processes.
JHEP 12 (2014) 079 A measurement of the inclusive $W \to \mu\nu$ production cross-section using
data from $pp$ collisions at a centre-of-mass energy of $\sqrt{s} = 7 {\rm \,
TeV}$ is presented. The ...analysis is based on an integrated luminosity of about
$1.0 {\rm \, fb}^{-1}$ recorded with the LHCb detector. Results are reported
for muons with a transverse momentum greater than $20 {\rm \, Ge\kern -0.1em
V\!/}c$ and pseudorapidity between 2.0 and 4.5. The $W^{+}$ and $W^{-}$
production cross-sections are measured to be $$\sigma_{W^{+} \to \mu^{+}\nu} =
861.0 \pm 2.0 \pm 11.2 \pm 14.7 {\rm \, pb},$$ $$\sigma_{W^{-} \to
\mu^{-}\overline{\nu}} = 675.8 \pm 1.9 \pm 8.8 \pm 11.6 {\rm \, pb},$$ where
the first uncertainty is statistical, the second is systematic and the third is
due to the luminosity determination. Cross-section ratios and differential
distributions as functions of the muon pseudorapidity are also presented. The
ratio of $W^{+}$ to $W^{-}$ cross-sections in the same fiducial kinematic
region is determined to be $$\frac{\sigma_{W^{+} \to \mu^{+}\nu}}{\sigma_{W^{-}
\to \mu^{-}\overline{\nu}}} = 1.274 \pm 0.005 \pm 0.009,$$ where the
uncertainties are statistical and systematic, respectively. Results are in good
agreement with theoretical predictions at next-to-next-to-leading order in
perturbative quantum chromodynamics.
JHEP 10 (2014) 005 A search for $CP$ violation using $T$-odd correlations is performed using the
four-body $D^0 \to K^+K^-\pi^+\pi^-$ decay, selected from semileptonic $B$
decays. The data sample ...corresponds to integrated luminosities of
$1.0\,\text{fb}^{-1}$ and $2.0\,\text{fb}^{-1}$ recorded at the centre-of-mass
energies of 7 TeV and 8 TeV, respectively. The $CP$-violating asymmetry
$a_{CP}^{T\text{-odd}}$ is measured to be $(0.18\pm 0.29\text{(stat)}\pm
0.04\text{(syst)})\%$. Searches for $CP$ violation in different regions of
phase space of the four-body decay, and as a function of the $D^0$ decay time,
are also presented. No significant deviation from the $CP$ conservation
hypothesis is found.
Phys. Rev. Lett. 113, 152003 (2014) A baryonic decay of the $B_c^+$ meson, $B_c^+\to J/\psi p\overline{p}\pi^+$,
is observed for the first time, with a significance of $7.3$ standard
deviations, in ...$pp$ collision data collected with the LHCb detector and
corresponding to an integrated luminosity of $3.0$ fb$^{-1}$ taken at
center-of-mass energies of $7$ and $8$ $\mathrm{TeV}$. With the $B_c^+\to
J/\psi \pi^+$ decay as normalization channel, the ratio of branching fractions
is measured to be \begin{equation*} \frac{\mathcal{B}(B_c^+\to J/\psi
p\overline{p}\pi^+)}{\mathcal{B}(B_c^+\to J/\psi \pi^+)} =
0.143^{\,+\,0.039}_{\,-\,0.034}\,(\mathrm{stat})\pm0.013\,(\mathrm{syst}).
\end{equation*} The mass of the $B_c^+$ meson is determined as
$M(B_c^+)=6274.0\pm1.8\,(\mathrm{stat})\pm0.4\,(\mathrm{syst})\,\mathrm{MeV}/c^2$,
using the $B_c^+\to J/\psi p\overline{p}\pi^+$ channel.
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