A search for decays of \(B_c^+\) mesons to two charm mesons is performed for the first time using data corresponding to an integrated luminosity of 3.0 fb\(^{-1}\), collected by the LHCb experiment ...in \(pp\) collisions at centre-of-mass energies of 7 and 8 TeV. The decays considered are \(B_c^+\to D^{(*)+}_{(s)} \overline{D}^{(*)0}\) and \(B_c^+\to D^{(*)+}_{(s)} D^{(*)0}\), which are normalised to high-yield \(B^+\to D^+_{(s)} \overline{D}^0\) decays. No evidence for a signal is found and limits are set on twelve \(B_c^+\) decay modes.
A search for \CP violation in Cabibbo-suppressed $D^{\pm}\rightarrow
K^0_{\mathrm{S}} K^{\pm}$ and $D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}}
\pi^{\pm}$ decays is performed using $pp$ collision data, ...corresponding to an
integrated luminosity of 3~fb$^{-1}$, recorded by the LHCb experiment. The
individual $CP$-violating asymmetries are measured to be \begin{eqnarray*}
\mathcal{A}_{CP}^{D^{\pm}\rightarrow K^0_{\mathrm{S}} K^{\pm}} & = & (+0.03
\pm 0.17 \pm 0.14) \%
\mathcal{A}_{CP}^{D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}} & = &
(+0.38 \pm 0.46 \pm 0.17) \%, \end{eqnarray*} assuming that $CP$ violation in
the Cabibbo-favoured decays is negligible. A combination of the measured
asymmetries for the four decay modes $D^{\pm}_{(s)}\rightarrow K^0_{\mathrm{S}}
K^{\pm}$ and $D^{\pm}_{(s)}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}$ gives the
sum \
\mathcal{A}_{CP}^{D^{\pm}\rightarrow K^0_{\mathrm{S}} K^{\pm}} +
\mathcal{A}_{CP}^{D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}} = (+0.41
\pm 0.49 \pm 0.26) \%. \ In all cases, the first uncertainties are statistical
and the second systematic. The results represent the most precise measurements
of these asymmetries to date and show no evidence for CP violation.
Phys. Rev. Lett. 113, 032001 (2014) Using a proton-proton collision data sample corresponding to an integrated
luminosity of 3 fb$^{-1}$ collected by LHCb at center-of-mass energies of 7 and
8 TeV, ...about 3800 $\Xi_b^0\to\Xi_c^+\pi^-$, $\Xi_c^+\to pK^-\pi^+$ signal
decays are reconstructed. From this sample, the first measurement of the
$\Xi_b^0$ baryon lifetime is made, relative to that of the $\Lambda_b^0$
baryon. The mass differences $M(\Xi_b^0)-M(\Lambda_b^0)$ and
$M(\Xi_c^+)-M(\Lambda_c^+)$ are also measured with precision more than four
times better than the current world averages. The resulting values are
$\frac{\tau_{\Xi_b^0}}{\tau_{\Lambda_b^0}} = 1.006\pm0.018\pm0.010$,
$M(\Xi_b^0) - M(\Lambda_b^0) = 172.44\pm0.39\pm0.17 MeV/c^2$, $M(\Xi_c^+) -
M(\Lambda_c^+) = 181.51\pm0.14\pm0.10 MeV/c^2$, where the first uncertainty is
statistical and the second is systematic. The relative rate of $\Xi_b^0$ to
$\Lambda_b^0$ baryon production is measured to be
$\frac{f_{\Xi_b^0}}{f_{\Lambda_b^0}}\frac{{\cal{B}}(\Xi_b^0\to\Xi_c^+\pi^-)}{{\cal{B}}(\Lambda_b^0\to\Lambda_c^+\pi^-)}\frac{{\cal{B}}(\Xi_c^+\to
pK^-\pi^+)}{{\cal{B}}(\Lambda_c^+\to pK^-\pi^+)} =
(1.88\pm0.04\pm0.03)\times10^{-2}$, where the first factor is the ratio of
fragmentation fractions, $b\to\Xi_b^0$ relative to $b\to\Lambda_b^0$. Relative
production rates as functions of transverse momentum and pseudorapidity are
also presented.
Amplitude models are constructed to describe the resonance structure of \({D^{0}\to K^{-}\pi^{+}\pi^{+}\pi^{-}}\) and \({D^{0} \to K^{+}\pi^{-}\pi^{-}\pi^{+}}\) decays using \(pp\) collision data ...collected at centre-of-mass energies of 7 and 8 TeV with the LHCb experiment, corresponding to an integrated luminosity of \(3.0\mathrm{fb}^{-1}\). The largest contributions to both decay amplitudes are found to come from axial resonances, with decay modes \(D^{0} \to a_1(1260)^{+} K^{-}\) and \(D^{0} \to K_1(1270/1400)^{+} \pi^{-}\) being prominent in \({D^{0}\to K^{-}\pi^{+}\pi^{+}\pi^{-}}\) and \(D^{0}\to K^{+}\pi^{-}\pi^{-}\pi^{+}\), respectively. Precise measurements of the lineshape parameters and couplings of the \(a_1(1260)^{+}\), \(K_1(1270)^{-}\) and \(K(1460)^{-}\) resonances are made, and a quasi model-independent study of the \(K(1460)^{-}\) resonance is performed. The coherence factor of the decays is calculated from the amplitude models to be \(R_{K3\pi} = 0.459\pm 0.010\,(\mathrm{stat}) \pm 0.012\,(\mathrm{syst}) \pm 0.020\,(\mathrm{model})\), which is consistent with direct measurements. These models will be useful in future measurements of the unitary-triangle angle \(\gamma\) and studies of charm mixing and \(C\!P\) violation.
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.
