Journal of High Energy Physics, 2016(1), 1-17 A search for $B_{(s)}^{0} \to K_{S}^{0} K^{*}(892)^{0}$ decays is performed
using $pp$ collision data, corresponding to an integrated luminosity of
...$1.0~\text{fb}^{-1}$, collected with the LHCb detector at a centre-of-mass
energy of $7~\text{TeV}$. The $B_{s}^{0} \to K_{S}^{0} K^{*}(892)^{0}$ decay is
observed for the first time, with a significance of 7.1 standard deviations.
The branching fraction is measured to be \begin{equation*}
\mathcal{B}(B_{s}^{0} \to \bar{K}^{0} K^{*}(892)^{0}) + \mathcal{B}(B_{s}^{0}
\to K^{0} \bar{K}^{*}(892)^{0}) = (16.4 \pm 3.4 \pm 2.3) \times 10^{-6},\\
\end{equation*} where the first uncertainty is statistical and the second is
systematic. No evidence is found for the decay $B^{0} \to K_{S}^{0}
K^{*}(892)^{0}$ and an upper limit is set on the branching fraction,
$\mathcal{B}(B^{0} \to \bar{K}^{0} K^{*}(892)^{0}) + \mathcal{B}(B^{0} \to
K^{0} \bar{K}^{*}(892)^{0}) < 0.96 \ \times 10^{-6}, $ at $90\,\% $ confidence
level. All results are consistent with Standard Model predictions.
JHEP09(2015)179 An angular analysis and a measurement of the differential branching fraction
of the decay $B^0_s\to\phi\mu^+\mu^-$ are presented, using data corresponding
to an integrated luminosity ...of $3.0\, {\rm fb^{-1}}$ of $pp$ collisions
recorded by the LHCb experiment at $\sqrt{s} = 7$ and $8\, {\rm TeV}$.
Measurements are reported as a function of $q^{2}$, the square of the dimuon
invariant mass and results of the angular analysis are found to be consistent
with the Standard Model. In the range $1<q^2<6\, {\rm GeV}^{2}/c^{4}$, where
precise theoretical calculations are available, the differential branching
fraction is found to be more than $3\,\sigma$ below the Standard Model
predictions.
Phys. Rev. Lett. 115, 111803 (2015) The branching fraction ratio $\mathcal{R}(D^{*}) \equiv
\mathcal{B}(\overline{B}^0 \to
D^{*+}\tau^{-}\overline{\nu}_{\tau})/\mathcal{B}(\overline{B}^0 \to
...D^{*+}\mu^{-}\overline{\nu}_{\mu})$ is measured using a sample of proton-proton
collision data corresponding to 3.0\invfb of integrated luminosity recorded by
the LHCb experiment during 2011 and 2012. The tau lepton is identified in the
decay mode $\tau^{-} \to \mu^{-}\overline{\nu}_{\mu}\nu_{\tau}$. The
semitauonic decay is sensitive to contributions from non-Standard-Model
particles that preferentially couple to the third generation of fermions, in
particular Higgs-like charged scalars. A multidimensional fit to kinematic
distributions of the candidate $\overline{B}^0$ decays gives
$\mathcal{R}(D^{*}) = 0.336 \pm 0.027(stat) \pm 0.030 (syst)$. This result,
which is the first measurement of this quantity at a hadron collider, is 2.1
standard deviations larger than the value expected from lepton universality in
the Standard Model.
A search is presented for long-lived particles with a mass between 25 and 50 GeV\(/c^2\) and a lifetime between 1 and 200 ps in a sample of proton-proton collisions at a centre-of-mass energy of ...\(\sqrt{s}=7\) TeV, corresponding to an integrated luminosity of 0.62 fb\(^{-1}\), collected by the LHCb detector. The particles are assumed to be pair-produced by the decay of a Standard Model-like Higgs boson. The experimental signature of the long-lived particle is a displaced vertex with two associated jets. No excess above the background is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime.
JHEP 1509 (2015) 084 A study is presented of central exclusive production of $\Upsilon(nS)$
states, where the $\Upsilon(nS)$ resonances decay to the $\mu^+\mu^-$ final
state, using $pp$ collision ...data recorded by the LHCb experiment. The
cross-section is measured in the rapidity range $2<y(\Upsilon)<4.5$ where the
muons are reconstructed in the pseudorapidity range $2<\eta(\mu^\pm)<4.5$. The
data sample corresponds to an integrated luminosity of 2.9 fb$^{-1}$ and was
collected at centre-of-mass energies of $7$ TeV and $8$ TeV. The measured
$\Upsilon(1S)$ and $\Upsilon(2S)$ production cross-sections are
\begin{eqnarray} \sigma(pp \to p\Upsilon(1S)p) &=& 9.0 \pm 2.1 \pm 1.7\textrm{
pb and}\nonumber\\ \sigma(pp \to p\Upsilon(2S)p) &=& 1.3 \pm 0.8 \pm
0.3\textrm{ pb},\nonumber \end{eqnarray} where the first uncertainties are
statistical and the second are systematic. The $\Upsilon(1S)$ cross-section is
also measured as a function of rapidity and is found to be in good agreement
with Standard Model predictions. An upper limit is set at 3.4 pb at the 95\%
confidence level for the exclusive $\Upsilon(3S)$ production cross-section,
including possible contamination from $\chi_b(3P)\to\Upsilon(3S)\gamma$ decays.
Phys. Rev. D 92, 112005 (2015) We report a study of the suppressed $B^-\to DK^-\pi^+\pi^-$ and favored
$B^-\to D\pi^-\pi^+\pi^-$ decays, where the neutral $D$ meson is detected
through its decays to ...the $K^{\mp}\pi^{\pm}$ and CP-even $K^+K^-$ and
$\pi^+\pi^-$ final states. The measurement is carried out using a proton-proton
collision data sample collected by the LHCb experiment, corresponding to an
integrated luminosity of 3.0~fb$^{-1}$. We observe the first significant
signals in the CP-even final states of the $D$ meson for both the suppressed
$B^-\to DK^-\pi^+\pi^-$ and favored $B^-\to D\pi^-\pi^+\pi^-$ modes, as well as
in the doubly Cabibbo-suppressed $D\to K^+\pi^-$ final state of the $B^-\to
D\pi^-\pi^+\pi^-$ decay. Evidence for the ADS suppressed decay $B^{-}\to
DK^-\pi^+\pi^-$, with $D\to K^+\pi^-$, is also presented. From the observed
yields in the $B^-\to DK^-\pi^+\pi^-$, $B^-\to D\pi^-\pi^+\pi^-$ and their
charge conjugate decay modes, we measure the value of the weak phase to be
$\gamma=(74^{+20}_{-19})^{\rm o}$. This is one of the most precise
single-measurement determinations of $\gamma$ to date.
JHEP08(2015)039 A measurement of the production cross-section for $Z$ bosons that decay to
muons is presented. The data were recorded by the LHCb detector during $pp$
collisions at a centre-of-mass ...energy of 7 TeV, and correspond to an integrated
luminosity of 1.0 fb$^{-1}$. The cross-section is measured for muons in the
pseudorapidity range $2.0 < \eta < 4.5$ with transverse momenta $p_{T} > 20$
GeV/c. The dimuon mass is restricted to $60 < M_{\mu^{+}\mu^{-}} < 120$
GeV/c$^{2}$. The measured cross-section is
$$\sigma_{Z\rightarrow\mu^{+}\mu^{-}} = (76.0 \pm 0.3 \pm 0.5 \pm 1.0 \pm 1.3)
\, \text{pb}$$ where the uncertainties are due to the sample size, systematic
effects, the beam energy and the luminosity. This result is in good agreement
with theoretical predictions at next-to-next-to-leading order in perturbative
quantum chromodynamics. The cross-section is also measured differentially as a
function of kinematic variables of the $Z$ boson. Ratios of the production
cross-sections of electroweak bosons are presented using updated LHCb
measurements of $W$ boson production. A precise test of the Standard Model is
provided by the measurement of the ratio
$$\frac{\sigma_{W^{+}\rightarrow\mu^{+}\nu_{\mu}} +
\sigma_{W^{-}\rightarrow\mu^{-}\bar{\nu}_{\mu}}}{\sigma_{Z\rightarrow\mu^{+}\mu^{-}}}
= 20.63\pm0.09\pm0.12\pm0.05,$$ where the uncertainty due to luminosity
cancels.
Invariant mass distributions of B+pi- and B0pi+ combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fb-1 of pp collision ...data, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the B_1(5721)^(0,+) and B_2*(5747)^(0,+) states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 5850--6000 MeV in both B+pi- and B0pi+ combinations. The structures are consistent with the presence of four excited B mesons, labelled B_J(5840)^(0,+) and B_J(5960)^(0,+), whose masses and widths are obtained under different hypotheses for their quantum numbers.
Phys. Rev. D 92, 052001 (2015) The associated production of a $W$ boson with a jet originating from either a
light parton or heavy-flavor quark is studied in the forward region using
proton-proton ...collisions. The analysis uses data corresponding to integrated
luminosities of 1.0 and $2.0\,{\rm fb}^{-1}$ collected with the LHCb detector
at center-of-mass energies of 7 and 8 TeV, respectively. The $W$ bosons are
reconstructed using the $W\to\mu\nu$ decay and muons with a transverse
momentum, $p_{\rm T}$, larger than 20 GeV in the pseudorapidity range
$2.0<\eta<4.5$. The partons are reconstructed as jets with $p_{\rm T} > 20$ GeV
and $2.2 < \eta < 4.2$. The sum of the muon and jet momenta must satisfy
$p_{\rm T} > 20$ GeV. The fraction of $W+$jet events that originate from beauty
and charm quarks is measured, along with the charge asymmetries of the
$W\!+\!b$ and $W\!+\!c$ production cross-sections. The ratio of the $W+$jet to
$Z+$jet production cross-sections is also measured using the $Z\to\mu\mu$
decay. All results are in agreement with Standard Model predictions.
JHEP 09 (2015) 006 A search is performed for the as yet unobserved baryonic $\Lambda_b
\rightarrow \Lambda \eta^\prime$ and $\Lambda_b \rightarrow \Lambda \eta$
decays with 3$fb^{-1}$ of ...proton-proton collision data recorded by the LHCb
experiment. The $B^0 \rightarrow K_S^0 \eta^\prime$ decay is used as a
normalisation channel. No significant signal is observed for the $\Lambda_b
\rightarrow \Lambda \eta^\prime$ decay. An upper limit is found on the
branching fraction of $\mathcal{B}(\Lambda_b \rightarrow \Lambda
\eta^\prime)<3.1\times10^{-6}$} at 90\% confidence level. Evidence is seen for
the presence of the $\Lambda_b \rightarrow \Lambda \eta$ decay at the level of
$3\sigma$ significance, with a branching fraction $\mathcal{B}(\Lambda_b
\rightarrow \Lambda \eta)=(9.3^{+7.3}_{-5.3})\times10^{-6}$}.
