The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity ...of 3.3 pb^{-1} collected in proton-proton collisions at a centre-of-mass energy of sqrt{s}=2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the Upsilon transverse momentum and rapidity, over the ranges p_T<15 GeV/c and 2.0<y<4.5. The total cross-sections in this kinematic region, assuming unpolarised production, are measured to be sigma(pp -> Upsilon(1S) X) x B(Upsilon(1S) -> mu+mu-) = 1.111 +/- 0.043 +/- 0.044 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S) -> mu+mu-) = 0.264 +/- 0.023 +/- 0.011 nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu+mu-) = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic.
JHEP 08(2014)143 The kinematic dependences of the relative production rates,
$f_{\Lambda_b^0}/f_d$, of $\Lambda_b^0$ baryons and $\bar{B}^0$ mesons are
measured using $\Lambda_b^0 \rightarrow ...\Lambda_c^+ \pi^-$ and $\bar{B}^0
\rightarrow D^+ \pi^-$ decays. The measurements use proton-proton collision
data, corresponding to an integrated luminosity of 1 fb$^{-1}$ at a
centre-of-mass energy of 7 TeV, recorded in the forward region with the LHCb
experiment. The relative production rates are observed to depend on the
transverse momentum, $p_T$, and pseudorapidity, $\eta$, of the beauty hadron,
in the studied kinematic region $1.5 < p_T < 40$ GeV/$c$ and $2 < \eta < 5$.
Using a previous LHCb measurement of $f_{\Lambda_b^0}/f_d$ in semileptonic
decays, the branching fraction $\mathcal{B}(\Lambda_b^0 \rightarrow \Lambda_c^+
\pi^-) = \Big( 4.30 \pm 0.03 \,\, ^{+0.12}_{-0.11} \pm 0.26 \pm 0.21 \Big)
\times 10^{-3}$ is obtained, where the first uncertainty is statistical, the
second is systematic, the third is from the previous LHCb measurement of
$f_{\Lambda_b^0}/f_d$ and the fourth is due to the $\bar{B}^0 \rightarrow D^+
\pi^-$ branching fraction. This is the most precise measurement of a
$\Lambda_b^0$ branching fraction to date.
JHEP 07 (2014) 094 Production of $\Upsilon$ mesons in proton-lead collisions at a
nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}=5 \mathrm{TeV}$ is studied
with the LHCb detector. The analysis ...is based on a data sample corresponding to
an integrated luminosity of $1.6 \mathrm{nb}^{-1}$. The $\Upsilon$ mesons of
transverse momenta up to $15 \mathrm{GeV}/c$ are reconstructed in the dimuon
decay mode. The rapidity coverage in the centre-of-mass system is $1.5<y<4.0$
(forward region) and $-5.0<y<-2.5$ (backward region). The forward-backward
production ratio and the nuclear modification factor for $\Upsilon(1S)$ mesons
are determined. The data are compatible with the predictions for a suppression
of $\Upsilon(1S)$ production with respect to proton-proton collisions in the
forward region, and an enhancement in the backward region. The suppression is
found to be smaller than in the case of prompt $J/\psi$ mesons.
Physics Letters B, 736, (2014) 186 The mixing-induced CP-violating phase $\phi_s$ in ${B}^0_s$ and
$\overline{B}^0_s$ decays is measured using the $J/\psi \pi^+\pi^-$ final state
in data, taken from ...3\,fb$^{-1}$ of integrated luminosity, collected with the
LHCb detector in 7 and 8 TeV centre-of-mass $pp$ collisions at the LHC. A
time-dependent flavour-tagged amplitude analysis, allowing for direct \CP
violation, yields a value for the phase $\phi_s=70\pm 68\pm 8$\,mrad. This
result is consistent with the Standard Model expectation and previous
measurements.
JHEP07(2014)140 Decays of the form $B^{0}_{(s)}\rightarrow J/\psi K_{{\rm S}}^{0} h^+
h^{\left(\prime\right) -}$ ($h^{(\prime)} = K, \pi$) are searched for in
proton-proton collision data ...corresponding to an integrated luminosity of $1.0
\, {\rm fb}^{-1}$ recorded with the LHCb detector. The first observation of the
$B^{0}_{s}\rightarrow J/\psi K_{{\rm S}}^{0} K^{\pm} \pi^{\mp}$ decay is
reported, with significance in excess of 10 standard deviations. The
$B^{0}\rightarrow J/\psi K_{{\rm S}}^{0} K^{+} K^{-}$ decay is also observed
for the first time. The branching fraction of $B^{0}\rightarrow J/\psi K_{{\rm
S}}^{0} \pi^{+} \pi^{-}$ is determined, to significantly better precision than
previous measurements, using $B^0 \rightarrow J/\psi K_{{\rm S}}^{0}$ as a
normalisation channel. Branching fractions and upper limits of the other
$B^{0}_{(s)}\rightarrow J/\psi K_{{\rm S}}^{0} h^+ h^{\left(\prime\right) -}$
modes are determined relative to that of the $B^{0}\rightarrow J/\psi K_{{\rm
S}}^{0} \pi^{+} \pi^{-}$ decay.
The \(\Lambda_b^0\to\Lambda\phi\) decay is observed using data corresponding to an integrated luminosity of 3.0fb\(^{-1}\) recorded by the LHCb experiment. The decay proceeds at leading order via a ...\(b\to s\bar{s}s\) loop transition and is therefore sensitive to the possible presence of particles beyond the Standard Model. A first observation is reported with a significance of \(5.9\) standard deviations. The value of the branching fraction is measured to be \((5.18\pm1.04\pm0.35\,^{+0.67}_{-0.62})\times10^{-6}\), where the first uncertainty is statistical, the second is systematic, and the third is related to external inputs. Triple-product asymmetries are measured to be consistent with zero.
JHEP 07 (2014) 041 Time-integrated $CP$ asymmetries in $D^0$ decays to the final states $K^-
K^+$ and $\pi^- \pi^+$ are measured using proton-proton collisions
corresponding to $3\mathrm{\,fb}^{-1}$ ...of integrated luminosity collected at
centre-of-mass energies of $7\mathrm{\,Te\kern -0.1em V}$ and
$8\mathrm{\,Te\kern -0.1em V}$. The $D^0$ mesons are produced in semileptonic
$b$-hadron decays, where the charge of the accompanying muon is used to
determine the initial flavour of the charm meson. The difference in $CP$
asymmetries between the two final states is measured to be \begin{align}
\Delta A_{CP} = A_{CP}(K^-K^+)-A_{CP}(\pi^-\pi^+) = (+0.14 \pm
0.16\mathrm{\,(stat)} \pm 0.08\mathrm{\,(syst)})\% \ . \nonumber \end{align} A
measurement of $A_{CP}(K^-K^+)$ is obtained assuming negligible $CP$ violation
in charm mixing and in Cabibbo-favoured $D$ decays. It is found to be
\begin{align}
A_{CP}(K^-K^+) = (-0.06 \pm 0.15\mathrm{\,(stat)} \pm 0.10\mathrm{\,(syst)})
\% \ ,\nonumber \end{align} where the correlation coefficient between $\Delta
A_{CP}$ and $A_{CP}(K^-K^+)$ is $\rho=0.28$. By combining these results, the
$CP$ asymmetry in the $D^0\rightarrow\pi^-\pi^+$ channel is
$A_{CP}(\pi^-\pi^+)=(-0.20\pm0.19\mathrm{\,(stat)}\pm0.10\mathrm{\,(syst)})\%$.
A search for the rare decay \(\Sigma^+ \to p \mu^+ \mu^-\) is performed using \(pp\) collision data recorded by the LHCb experiment at centre-of-mass energies \(\sqrt{s} = 7\) and \(8\) TeV, ...corresponding to an integrated luminosity of \(3 fb^{-1}\). An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured \(\Sigma^+ \to p \mu^+ \mu^-\) branching fraction is \((2.2\,^{+\,1.8}_{-\,1.3})\times 10^{-8}\), where statistical and systematic uncertainties are included, which is consistent with the Standard Model prediction.
Phys. Lett. B 736, 154-162 (2014) Using a data sample of pp collisions corresponding to an integrated
luminosity of $3~ \rm fb^{-1}$, the $\Xi_b^-$ and $\Omega_b^-$ baryons are
reconstructed in the ...$\Xi_b^- \rightarrow J/\psi \Xi^-$ and $\Omega_b^-
\rightarrow J/\psi \Omega^-$ decay modes and their lifetimes measured to be
$\tau (\Xi_b^-) = 1.55\, ^{+0.10}_{-0.09}~{\rm(stat)} \pm 0.03\,{\rm(syst)}$
ps,
$\tau (\Omega_b^-) = 1.54\, ^{+0.26}_{-0.21}~{\rm(stat)} \pm
0.05\,{\rm(syst)}$ ps.
These are the most precise determinations to date. Both measurements are in
good agreement with previous experimental results and with theoretical
predictions.
Phys. Rev. D 90, 012003 (2014) The resonant structure of the reaction $\overline{B}^0\rightarrow J/\psi
\pi^+\pi^-$ is studied using data from 3 fb$^{-1}$ of integrated luminosity
collected by the ...LHCb experiment, one-third at 7 Tev center-of-mass energy and
the remainder at 8 Tev. The invariant mass of the $\pi^+\pi^-$ pair and three
decay angular distributions are used to determine the fractions of the resonant
and non-resonant components. Six interfering $\pi^+\pi^-$ states: $\rho(770)$,
$f_0(500)$, $f_2(1270)$, $\rho(1450)$, $\omega(782)$ and $\rho(1700)$ are
required to give a good description of invariant mass spectra and decay angular
distributions. The positive and negative CP fractions of each of the resonant
final states are determined. The $f_0(980)$ meson is not seen and the upper
limit on its presence, compared with the observed $f_0(500)$ rate, is
inconsistent with a model of tetraquark substructure for these scalar mesons at
the eight standard deviation level. In the $q\overline{q}$ model, the absolute
value of the mixing angle between the $f_0(980)$ and the $f_0(500)$ scalar
mesons is limited to be less than $17^{\circ}$ at 90% confidence level.
