JHEP 1502 (2015) 129 The cross-section for inelastic proton-proton collisions, with at least one
prompt long-lived charged particle of transverse momentum $p_{\rm T}>0.2$
GeV/$c$ in the ...pseudorapidity range $2.0<\eta<4.5$, is measured by the LHCb
experiment at a centre-of-mass energy of $\sqrt{s}=7$ TeV. The cross-section in
this kinematic range is determined to be $\sigma_{\rm inel}^{\rm acc} = 55.0
\pm 2.4$ mb within the spectrometer acceptance with an experimental uncertainty
that is dominated by systematic contributions. Extrapolation to the full phase
space, using PYTHIA 6, yields $\sigma_{\rm inel} = 66.9 \pm 2.9 \pm 4.4$ mb,
where the first uncertainty is experimental and the second is due to the
extrapolation.
Physics Letters B 742 (2015) 29-37 The difference in total widths between the $B_c^+$ and $B^+$ mesons is
measured using 3.0fb$^{-1}$ of data collected by the LHCb experiment in 7 and 8
TeV ...centre-of-mass energy proton-proton collisions at the LHC. Through the
study of the time evolution of $B_c^+ \rightarrow J/\psi \pi^+$ and
$B^+\rightarrow J/\psi K^+$ decays, the width difference is measured to be
$$ \Delta\Gamma \equiv \Gamma_{B_c^+} - \Gamma_{B^+} = 4.46 \pm 0.14 \pm
0.07mm^{-1}c,$$ where the first uncertainty is statistical and the second
systematic. The known lifetime of the $B^+$ meson is used to convert this to a
precise measurement of the $B_c^+$ lifetime,
$$\tau_{B_c^+} = 513.4 \pm 11.0 \pm 5.7fs,$$ where the first uncertainty is
statistical and the second systematic.
Phys. Rev. Lett. 114, 062004 (2015) Two structures are observed close to the kinematic threshold in the $\Xi_b^0
\pi^-$ mass spectrum in a sample of proton-proton collision data, corresponding
to an ...integrated luminosity of 3.0 fb$^{-1}$ recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content $bds$ are
expected in this mass region: the spin-parity $J^P = \frac{1}{2}^+$ and
$J^P=\frac{3}{2}^+$ states, denoted $\Xi_b^{\prime -}$ and $\Xi_b^{*-}$.
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
$m(\Xi_b^{\prime -}) - m(\Xi_b^0) - m(\pi^{-}) = 3.653 \pm 0.018 \pm 0.006$
MeV$/c^2$,
$m(\Xi_b^{*-}) - m(\Xi_b^0) - m(\pi^{-}) = 23.96 \pm 0.12 \pm 0.06$
MeV$/c^2$,
$\Gamma(\Xi_b^{*-}) = 1.65 \pm 0.31 \pm 0.10$ MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
$\Gamma(\Xi_b^{\prime -}) < 0.08$ MeV at 95% confidence level. Relative
production rates of these states are also reported.
Phys. Rev. Lett. 114, 041801 (2015) The time-dependent $CP$ asymmetry in $B_s^0 \to J/\psi K^+K^-$ decays is
measured using $pp$ collision data, corresponding to an integrated luminosity
of ...$3.0$fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies
of $7$ and $8$TeV. In a sample of 96 000 $B_s^0 \to J/\psi K^+K^-$ decays, the
$CP$-violating phase $\phi_s$ is measured, as well as the decay widths
$\Gamma_{L}$ and $\Gamma_{H}$ of the light and heavy mass eigenstates of the
$B_s^0-\bar{B}_s^0$ system. The values obtained are $\phi_s = -0.058 \pm 0.049
\pm 0.006$ rad, $\Gamma_s \equiv (\Gamma_{L}+\Gamma_{H})/2 = 0.6603 \pm 0.0027
\pm 0.0015$ps$^{-1}$, and$\Delta\Gamma_s \equiv \Gamma_{L} - \Gamma_{H} =
0.0805 \pm 0.0091 \pm 0.0032$ps$^{-1}$, where the first uncertainty is
statistical and the second systematic. These are the most precise single
measurements of those quantities to date. A combined analysis with $B_s^{0} \to
J/\psi \pi^+\pi^-$ decays gives $\phi_s = -0.010 \pm 0.039 $rad. All
measurements are in agreement with the Standard Model predictions. For the
first time the phase $\phi_s$ is measured independently for each polarisation
state of the $K^+K^- $ system and shows no evidence for polarisation
dependence.
Phys. Rev. Lett. 114, 132001 (2015) Production of $B_c^+$ mesons in proton-proton collisions at a center-of-mass
energy of 8 TeV is studied with data corresponding to an integrated luminosity
of ...$2.0~{\rm fb}^{-1}$ recorded by the LHCb experiment. The ratio of production
cross-sections times branching fractions between the $B_c^+\to J/\psi \pi^+$
and $B^+\to J/\psi K^+$ decays is measured as a function of transverse momentum
and rapidity in the regions $0 < p_{\rm T} < 20~{\rm GeV}/c$ and $2.0 < y <
4.5$. The ratio in this kinematic range is measured to be
$(0.683\pm0.018\pm0.009)\%$, where the first uncertainty is statistical and the
second systematic.
Phys. Lett. B742 (2015) 38-49 Time-dependent CP violation is measured in the $B^0\rightarrow
J/\psi\pi^+\pi^-$ channel for each $\pi^+\pi^-$ resonant final state using data
collected with an ...integrated luminosity of 3.0 fb$^{-1}$ in $pp$ collisions
using the LHCb detector. The final state with the largest rate,
$J/\psi\rho^0(770)$, is used to measure the CP-violating angle $2\beta^{\rm
eff}$ to be $(41.7\pm 9.6_{-6.3}^{+2.8})^{\circ}$. This result can be used to
limit the size of penguin amplitude contributions to CP violation measurements
in, for example, $B_s^0\rightarrow J/\psi\phi$ decays. Assuming approximate
SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the
CP-violating phase $\phi_s$ is limited to be within the interval
$-1.05^\circ$, +$1.18^\circ$ at 95% confidence level. Changes to the limit
due to SU(3) symmetry breaking effects are also discussed.
JHEP 01 (2015) 064 The associated production of a Z boson or an off-shell photon $\gamma^*$ with
a bottom quark in the forward region is studied using proton-proton collisions
at a centre-of-mass ...energy of $7{\mathrm{\,Te\kern -0.1em V}}$. The Z bosons
are reconstructed in the ${\text{Z}/\gamma^*}\!\rightarrow{\mu^{+}\mu^{-}}$
final state from muons with a transverse momentum larger than
$20{\mathrm{\,Ge\kern -0.1em V}}$, while two transverse momentum thresholds are
considered for jets ($10{\mathrm{\,Ge\kern -0.1em V}}$ and
$20{\mathrm{\,Ge\kern -0.1em V}}$). Both muons and jets are reconstructed in
the pseudorapidity range $2.0 < \eta < 4.5$. The results are based on data
corresponding to $1.0{\,\mbox{fb}^{-1}}$ recorded in 2011 with the LHCb
detector. The measurement of the Z+b-jet cross-section is normalized to the
Z+jet cross-section. The measured cross-sections are \begin{equation*}
\sigma(\text{$\text{Z}/\gamma^*(\mu^{+}\mu^{-})$+b-jet}) = 295 \pm
60~(\text{stat}) \pm 51~(\text{syst}) \pm 10~(\text{lumi}) {\,\mbox{fb}}
\end{equation*} for ${p_{\rm T}}$(jet)$>10{\mathrm{\,Ge\kern -0.1em V}}$, and
\begin{equation*} \sigma(\text{$\text{Z}/\gamma^*(\mu^{+}\mu^{-})$+b-jet}) =
128 \pm 36~(\text{stat}) \pm 22~(\text{syst}) \pm 5~(\text{lumi}) {\,\mbox{fb}}
\end{equation*} for ${p_{\rm T}}$(jet)$>20{\mathrm{\,Ge\kern -0.1em V}}$.
JHEP 1501 (2015) 024 A study of $B^0$~and $B^0_s$ meson decays into $J/\psi\eta$~and
$J/\psi\eta^{\prime}$ final states is performed using a data set of
proton-proton collisions at centre-of-mass ...energies of 7 and 8TeV, collected by
the LHCb experiment and corresponding to 3.0fb$^{-1}$ of integrated luminosity.
The decay $B^0 \rightarrow J/\psi \eta^{\prime}$ is observed for thefirst time.
The following ratios of branching fractions are measured: $$
\frac{\mathcal{B}(B^0 \rightarrow J/\psi \eta^{\prime})}{\mathcal{B}(B^0_s
\rightarrow J/\psi \eta^{\prime})} =
(2.28\pm0.65\,(stat)\,\pm0.10\,(syst)\,\pm0.13\,(f_{s}/f_{d}))\times10^{-2},$$
$$ \frac{\mathcal{B}(B^0 \rightarrow J/\psi \eta)}{\mathcal{B}(B^0_s
\rightarrow J/\psi \eta)} =
(1.85\pm0.61\,(stat)\,\pm0.09\,(syst)\,\pm0.11\,(f_{s}/f_{d}))\times10^{-2},$$
where the third uncertainty is related to the present knowledge of
$f_{s}/f_{d}$, the ratio between the probabilities for a $b$ quark to form a
$B^0_s$ or $B^0$ meson. The branching fraction ratios are used to determine the
parameters of $\eta-\eta^{\prime}$ meson mixing. In addition, the first
evidence for the decay $B^0_s \rightarrow \psi(2S) \eta^{\prime}$ is reported,
and the relative branching fraction is measured,
$$\frac{\mathcal{B}(B^0_s \rightarrow \psi(2S)
\eta^{\prime})}{\mathcal{B}(B^0_s \rightarrow J/\psi \eta^{\prime})} =
(38.7\pm9.0\,(stat)\,\pm1.3\,(syst)\,\pm0.9(\mathcal{B}))\times10^{-2},$$
where the third uncertainty is due to the limited knowledge of the branching
fractions of $J/\psi$ and $\psi(2S)$~mesons.
Phys. Lett. B 740 (2015) 158 A search for time-integrated CP violation in the Cabibbo-suppressed decay
$D^0\to\pi^-\pi^+\pi^0$ is performed using for the first time an unbinned
model-independent ...technique known as the energy test. Using proton-proton
collision data, corresponding to an integrated luminosity of 2.0 fb$^{-1}$
collected by the LHCb detector at a centre-of-mass energy of $\sqrt{s}$ = 8
TeV, the world's best sensitivity to CP violation in this decay is obtained.
The data are found to be consistent with the hypothesis of CP symmetry with a
p-value of (2.6 +/- 0.5)%.
JHEP 02 (2015) 121 A search for the lepton flavour violating decay $\tau^-\to \mu^-\mu^+\mu^-$
is performed with the LHCb experiment. The data sample corresponds to an
integrated luminosity of ...$1.0\mathrm{\,fb}^{-1}$ of proton-proton collisions at
a centre-of-mass energy of $7\mathrm{\,Te\kern -0.1em V}$ and
$2.0\mathrm{\,fb}^{-1}$ at $8\mathrm{\,Te\kern -0.1em V}$. No evidence is found
for a signal, and a limit is set at $90\%$ confidence level on the branching
fraction, $\mathcal{B}(\tau^-\to \mu^-\mu^+\mu^-) < 4.6 \times 10^{-8}$.
