Phys. Rev. D 101, 072004 (2020) The element $|V_{cb}|$ of the Cabibbo-Kobayashi-Maskawa matrix is measured
using semileptonic $B_s^0$ decays produced in proton-proton collision data
collected with ...the LHCb detector at center-of-mass energies of 7 and 8 TeV,
corresponding to an integrated luminosity of 3 fb$^{-1}$. Rates of $B_s^0 \to
D_s^{-} \mu^+ \nu_{\mu}$ and $B_s^0 \to D_s^{*-} \mu^+ \nu_{\mu}$ decays are
analyzed using hadronic form-factor parametrizations derived either by Caprini,
Lellouch and Neubert (CLN) or by Boyd, Grinstein and Lebed (BGL). The measured
values of $|V_{cb}|$ are ${(41.4 \pm 0.6 \pm 0.9 \pm 1.2)\times 10^{-3}}$ and
${(42.3 \pm 0.8 \pm 0.9 \pm 1.2)\times 10^{-3}}$ in the CLN and BGL
parametrization, respectively. The first uncertainty is statistical, the second
systematic, and the third is due to the external inputs used in the
measurement. These results are in agreement with those obtained from decays of
$B^+$ and $B^0$ mesons. They are the first determinations of $|V_{cb}|$ at a
hadron-collider experiment and the first using $B_s^0$ meson decays.
Phys. Rev. Lett. 124, 082002 (2020) We report four narrow peaks in the $\Xi_b^0K^-$ mass spectrum obtained using
$pp$ collisions at center-of-mass energies of 7, 8 and 13 TeV, corresponding to
a ...total integrated luminosity of 9 fb$^{-1}$ recorded by the LHCb experiment.
Referring to these states by their mass, the mass values are \begin{align*}
m(\Omega_b(6316)^-) &= 6315.64\pm0.31\pm0.07\pm0.50 {\rm MeV}, \\
m(\Omega_b(6330)^-) &= 6330.30\pm0.28\pm0.07\pm0.50 {\rm MeV}, \\
m(\Omega_b(6340)^-) &= 6339.71\pm0.26\pm0.05\pm0.50 {\rm MeV}, \\
m(\Omega_b(6350)^-) &= 6349.88\pm0.35\pm0.05\pm0.50 {\rm MeV},
\end{align*}where the uncertainties are statistical, systematic and the last is
due to the knowledge of the $\Xi_b^0$ mass. The natural widths of the three
lower mass states are consistent with zero, and the 90% confidence-level upper
limits are determined to be ${\Gamma(\Omega_b(6316)^-)<2.8}$ MeV,
${\Gamma(\Omega_b(6330)^-)<3.1}$ MeV and ${\Gamma(\Omega_b(6340)^-)<1.5}$ MeV.
The natural width of the $\Omega_b(6350)^-$ peak is $1.4^{+1.0}_{-0.8}\pm0.1$
MeV, which is 2.5$\sigma$ from zero and corresponds to an upper limit of 2.8
MeV. The peaks have local significances ranging from 3.6$\sigma$ to
7.2$\sigma$. After accounting for the look-elsewhere effect, the significances
of the $\Omega_b(6316)^-$ and $\Omega_b(6330)^-$ peaks are reduced to
2.1$\sigma$ and 2.6$\sigma$ respectively, while the two higher mass peaks
exceed 5$\sigma$. The observed peaks are consistent with expectations for
excited $\Omega_b^-$ resonances.
Phys. Rev. D 102, 051101 (2020) A search for $C\!P$ violation in the $\Lambda_b^0 \to p \pi^- \pi^+ \pi^-$
decay is performed using LHCb data corresponding to an integrated luminosity of
...6.6$\,fb^{-1}$ collected in $pp$ collisions at centre-of-mass energies of 7, 8
and 13$\,Te\kern -0.1em V$. The analysis uses both triple product asymmetries
and the unbinned energy test method. The highest significances of $C\!P$
asymmetry are 2.9 standard deviations from triple product asymmetries and 3.0
standard deviations for the energy test method. Once the global $p$-value is
considered, all results are consistent with no $C\!P$ violation. Parity
violation is observed at a significance of $5.5$ standard deviations for the
triple product asymmetry method and $5.3$ standard deviations for the energy
test method.
J. High Energ. Phys. 2020, 40 (2020) The ratio of branching fractions of the decays $\Lambda^{0}_{b}\to
pK^{-}e^{+}e^{-}$ and $\Lambda^{0}_{b}\to pK^{-}\mu^{+}\mu^{-}$, $R^{-1}_{pK}$,
is measured for ...the first time using proton-proton collision data corresponding
to an integrated luminosity of 4.7 $fb^{-1}$ recorded with the LHCb experiment
at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared
range $0.1 < q^{2} < 6.0$ $GeV^{2}/c^{4}$ and the $pK^{-}$ mass range
$m(pK^{-}) < 2600$ $MeV/c^{2}$, the ratio of branching fractions is measured to
be $R^{-1}_{pK} = 1.17 ^{+0.18}_{-0.16} \pm 0.07$, where the first uncertainty
is statistical and the second systematic. This is the first test of lepton
universality with b baryons and the first observation of the decay
$\Lambda^{0}_{b}\to pK^{-}e^{+}e^{-}$.
Journal of High Energy Physics, 03 (2020) 147 The decay-time-dependent $CP$ asymmetry in $B^0 \to D^{*\pm}D^{\mp}$ decays
is measured using a data set corresponding to an integrated luminosity of
...$9$fb$^{-1}$ recorded by the LHCb detector in proton-proton collisions at
centre-of-mass energies of 7, 8 and 13 TeV. The $CP$ parameters are measured as
$ S_{D^*D} = -0.861 \pm 0.077\,\text{(stat)} \pm 0.019 \,\text{(syst)}\,, $
$ \Delta S_{D^*D} = 0.019 \pm 0.075 \,\text{(stat)} \pm 0.012 \,\text{(syst)}
\,, $
$ C_{D^*D} = -0.059 \pm 0.092 \,\text{(stat)} \pm 0.020 \,\text{(syst)} \,, $
$ \Delta C_{D^*D} = -0.031 \pm 0.092 \,\text{(stat)} \pm 0.016
\,\text{(syst)} \,, $
$ {\cal A}_{D^*D} = 0.008 \pm 0.014 \,\text{(stat)} \pm 0.006
\,\text{(syst)}\,. $
The analysis provides the most precise single measurement of $CP$ violation
in this decay channel to date. All parameters are consistent with their current
world average values.
Phys. Rev. Lett. 124, 111802 (2020) Ratios of isospin amplitudes in hadron decays are a useful probe of the
interplay between weak and strong interactions, and allow searches for physics
beyond the ...Standard Model. We present the first results on isospin amplitudes
in $b$-baryon decays, using data corresponding to an integrated luminosity of
8.5 fb$^{-1}$, collected with the LHCb detector in $pp$ collisions at center of
mass energies of 7, 8 and 13 TeV. The isospin amplitude ratio
$|A_1(\Lambda_b^0\to J/\psi \Sigma^0)/A_0(\Lambda_b^0\to J/\psi\Lambda)|$,
where the subscript on $A$ indicates the final-state isospin, is measured to be
less than 1/21.8 at 95\% confidence level. The Cabibbo suppressed $\Xi_b^0\to
J/\psi\Lambda$ decay is observed for the first time, allowing for the
measurement $|A_0(\Xi_b^0\to J/\psi\Lambda)/A_{1/2}(\Xi_b^0\to J/\psi\Xi^0)|
=0.37 \pm 0.06\pm 0.02$, where the uncertainties are statistical and
systematic, respectively.
JHEP 03 (2020) 146 The Cabibbo-suppressed semileptonic decay $B^{+}\to
p\overline{p}\mu^{+}\nu_{\mu}$ is observed for the first time using a sample of
$pp$ collisions corresponding to an integrated ...luminosity of 1.0, 2.0 and
1.7fb$^{-1}$ at centre-of-mass energies of 7, 8 and 13TeV, respectively. The
differential branching fraction is measured as a function of the
$p\overline{p}$ invariant mass using the decay mode $B^{+}\to J/\psi K^{+}$ for
normalisation. The total branching fraction is measured to be \begin{align*}
\mathcal{B}(B^{+}\to p\overline{p}\mu^{+}\nu_{\mu}) = (5.27 ^{+0.23}_{-0.24}
\pm 0.21 \pm 0.15)\times 10^{-6}, \end{align*} where the first uncertainty is
statistical, the second systematic and the third is from the uncertainty on the
branching fraction of the normalisation channel.
JHEP 02 (2020) 049 A measurement of the $\Xi_{cc}^{++}$ mass is performed using data collected
by the LHCb experiment between 2016 and 2018 in $pp$ collisions at a
centre-of-mass energy of 13 TeV, ...corresponding to an integrated luminosity of
5.6 $\mathrm{fb}^{-1}$. The $\Xi_{cc}^{++}$ candidates are reconstructed via
the decay modes $\Xi_{cc}^{++}\to\Lambda_c^+K^-\pi^+\pi^+$ and
$\Xi_{cc}^{++}\to\Xi_c^+\pi^+$. The result, $3621.55 \pm 0.23{\rm\,(stat)\,}
\pm 0.30 {\rm\,(syst)\,}{\rm MeV}/c^2$, is the most precise measurement of the
$\Xi_{cc}^{++}$ mass to date.
Phys. Rev. D 101, 032005 (2020) A four-body amplitude analysis of the $B^- \to D^{*+} \pi^- \pi^-$ decay is
performed, where fractions and relative phases of the various resonances
contributing to ...the decay are measured. Several quasi-model-independent
analyses are performed aimed at searching for the presence of new states and
establishing the quantum numbers of previously observed charmed meson
resonances. In particular the resonance parameters and quantum numbers are
determined for the $D_1(2420)$, $D_1(2430)$, $D_0(2550)$, $D^*_1(2600)$,
$D_2(2740)$ and $D^*_3(2750)$ states. The mixing between the $D_1(2420)$ and
$D_1(2430)$ resonances is studied and the mixing parameters are measured. The
dataset corresponds to an integrated luminosity of 4.7 $fb^{-1}$, collected in
proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV with the
LHCb detector.
Eur. Phys. J. C80 (2020) 191 Using a data sample corresponding to an integrated luminosity of
$2.0\,fb^{-1}$, collected by the LHCb experiment, the production of the
$\eta_c(1S)$ state in ...proton-proton collisions at a centre-of-mass energy of
$\sqrt{s}=13 \text{ TeV}$ is studied in the rapidity range ${2.0 < y < 4.5}$
and in the transverse momentum range ${6.5 < p_{T} < 14.0\text{ GeV}}$. The
cross-section for prompt production of $\eta_c(1S)$ mesons relative to that of
the $J/\psi$ meson is measured using the ${p\bar{p}}$ decay mode and is found
to be ${\sigma_{\eta_c(1S)}/\sigma_{J/\psi} = 1.69 \pm 0.15 \pm 0.10 \pm
0.18}$. The quoted uncertainties are, in order, statistical, systematic and due
to uncertainties on the branching fractions of the ${J/\psi\to p \bar{p}}$ and
${\eta_c\to p \bar{p}}$ decays. The prompt $\eta_c(1S)$ production
cross-section is determined to be ${\sigma_{\eta_c(1S)} = 1.26 \pm 0.11\pm 0.08
\pm 0.14 \,\mu b}$, where the last uncertainty includes that on the ${J/\psi}$
meson cross-section. The ratio of the branching fractions of $b$-hadron decays
to the $\eta_c(1S)$ and ${J/\psi}$ states is measured to be
${\mathcal{B}_{b\to\eta_c X}/\mathcal{B}_{b\to J/\psi X} = 0.48 \pm 0.03 \pm
0.03 \pm 0.05}$, where the last uncertainty is due to those on the branching
fractions of the ${J/\psi \to p \bar{p}}$ and ${\eta_c\to p \bar{p}}$ decays.
The difference between the ${J/\psi}$ and $\eta_c(1S)$ masses is also
determined to be ${113.0 \pm 0.7 \pm 0.1\text{ MeV}}$, which is the most
precise single measurement of this quantity to date.
