A combination of measurements sensitive to the CKM angle γ from LHCb is performed. The inputs are from analyses of time-integrated B + → DK +, B 0 → DK ∗0, B 0 → DK +π− and B + → DK +π+π− tree-level ...decays. In addition, results from a time-dependent analysis of B s 0 → D s ∓ K ± decays are included. The combination yields γ = (72. 2 − 7.3 + 6.8 )°, where the uncertainty includes systematic effects. The 95.5% confidence level interval is determined to be γ ∈ 55.9, 85.2°. A second combination is investigated, also including measurements from B + → Dπ+ and B + → Dπ+π−π+ decays, which yields compatible results.
The calibration and performance of the LHCb Calorimeter system in Run 1 and 2 at the LHC are described. After a brief description of the sub-detectors and of their role in the trigger, the ...calibration methods used for each part of the system are reviewed. The changes which occurred with the increase of beam energy in Run 2 are explained. The performances of the calorimetry for \(\gamma\) and \(\pi^0\) are detailed. A few results from collisions recorded at \(\sqrt {s}\) = 7, 8 and 13 TeV are shown.
Phys. Rev. D92, 011102 (2015) Angular correlations in $B^+\to X(3872) K^+$ decays, with $X(3872)\to \rho^0
J/\psi$, $\rho^0\to\pi^+\pi^-$ and $J/\psi \to\mu^+\mu^-$, are used to measure
orbital ...angular momentum contributions and to determine the $J^{PC}$ value of
the $X(3872)$ meson. The data correspond to an integrated luminosity of 3.0
fb$^{-1}$ of proton-proton collisions collected with the LHCb detector. This
determination, for the first time performed without assuming a value for the
orbital angular momentum, confirms the quantum numbers to be $J^{PC}=1^{++}$.
The $X(3872)$ is found to decay predominantly through S wave and an upper limit
of $4\%$ at $95\%$ C.L. is set on the fraction of D wave.
Using three- and four-body decays of \(D\) mesons produced in semileptonic \(b\)-hadron decays, precision measurements of \(D\) meson mass differences are made together with a measurement of the ...\(D^{0}\) mass. The measurements are based on a dataset corresponding to an integrated luminosity of \(1.0 fb^{-1}\) collected in \(pp\) collisions at 7\,TeV. Using the decay \(D^0 \rightarrow K^{+} K^{-} K^{-} \pi^{+}\), the \(D^0\) mass is measured to be \(M(D^0) &=& 1864.75 \pm 0.15 \,({\rm stat}) \pm 0.11 \,({\rm syst}) \, \textrm{MeV/c^2}\). The mass differences \(M(D^{+}) - M(D^{0}) = 4.76 \pm 0.12 \,({\rm stat}) \pm 0.07 \,({\rm syst}) \, \textrm{MeV/c^2}\) and \(M(D^{+}_s) - M(D^{+}) = 98.68 \pm 0.03 \,({\rm stat}) \pm 0.04 \,({\rm syst}) \, \textrm{MeV/c^2}\) are measured using the \(D^0 \rightarrow K^{+} K^{-} \pi^{+} \pi^{-}\) and \(D^{+}_{(s)} \rightarrow K^{+}K^{-} \pi^{+}\) modes.
Journal of High Energy Physics Volume 2013, Number 5 (2013), 132 Limits on the cross-section times branching fraction for neutral Higgs
bosons, produced in $pp$ collisions at $\sqrt{s} = 7$ TeV, and ...decaying to two
tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The
result is based on a dataset, corresponding to an integrated luminosity of 1.0
$\mathrm{fb}^{-1}$, collected with the LHCb detector. Candidates are identified
by reconstructing final states with two muons, a muon and an electron, a muon
and a hadron, or an electron and a hadron. A model independent upper limit at
the 95% confidence level is set on a neutral Higgs boson cross-section times
branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to
0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model
expectation. An upper limit on $\tan\beta$ in the Minimal Supersymmetric Model
is set in the $m_{h^0}^\mathrm{max}$ scenario. It ranges from 34 for a CP-odd
Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140
GeV.
Eur.Phys.J. C73 (2013) 2462 The branching fractions of the decay $B^{+} \to p \bar p K^{+}$ for different
intermediate states are measured using data, corresponding to an integrated
luminosity of ...$1.0 fb^{-1}$, collected by the LHCb experiment. The total
branching fraction, its charmless component $(M_{p\bar p} <2.85 {GeV/}c^{2})$
and the branching fractions via the resonant $c\bar c$ states $\eta_{c}(1S)$
and $\psi(2S)$ relative to the decay via a $J/\psi$ intermediate state are
{align*} \frac{{\mathcal B}(B^{+} \to p \bar p K^{+})_{total}}{{\mathcal
B}(B^{+} \to J/\psi K^{+} \to p \bar p K^{+})}=& \, 4.91 \pm 0.19 \, {(\rm
stat)} \pm 0.14 \, {(\rm syst)}, \frac{{\mathcal B}(B^{+} \to p \bar p
K^{+})_{M_{p\bar p} <2.85 {GeV/}c^{2}}}{{\mathcal B}(B^{+} \to J/\psi K^{+} \to
p \bar p K^{+})}=& \, 2.02 \pm 0.10 \, {(\rm stat)}\pm 0.08 \, {(\rm syst)},
\frac{{\mathcal B} (B^{+} \to \eta_{c}(1S) K^{+} \to p \bar p K^{+})}{{\mathcal
B}(B^{+} \to J/\psi K^{+} \to p \bar p K^{+})} = & \, 0.578 \pm 0.035 \, {(\rm
stat)} \pm 0.027 \, {(\rm syst)}, \frac{{\mathcal B} (B^{+} \to \psi(2S) K^{+}
\to p \bar p K^{+})}{{\mathcal B}(B^{+} \to J/\psi K^{+} \to p \bar p K^{+})}=&
\, 0.080 \pm 0.012 \, {(\rm stat)} \pm 0.009 \, {(\rm syst)}. {align*} Upper
limits on the $B^{+}$ branching fractions into the $\eta_{c}(2S)$ meson and
into the charmonium-like states X(3872) and X(3915) are also obtained.
Phys. Rev. Lett. 110, 241802 (2013) A first flavour-tagged measurement of the time-dependent CP-violating
asymmetry in $B_s^0 \to \phi\phi$ decays is presented. In this decay channel,
the ...CP-violating weak phase arises due to CP violation in the interference
between $B_s^0$-$\bar{B}_s^0$ mixing and the $b \to s \bar{s} s $ gluonic
penguin decay amplitude. Using a sample of $pp$ collision data corresponding to
an integrated luminosity of $1.0\; fb^{-1}$ and collected at a centre-of-mass
energy of $7 \rm TeV$ with the LHCb detector, $880\ \B_s^0 \to \phi\phi$ signal
decays are obtained. The CP-violating phase is measured to be in the interval
-2.46, -0.76 \rm rad$ at 68% confidence level. The p-value of the Standard
Model prediction is 16%.
Phys Lett B 723 (2013) 44-53 An analysis of $B^{\pm}\to DK^{\pm}$ and $B^{\pm}\to D\pi^{\pm}$ decays is
presented where the $D$ meson is reconstructed in the four-body final state
$K^{\pm}\pi^{\mp} ...\pi^+ \pi^-$. Using LHCb data corresponding to an integrated
luminosity of $1.0{\rm \,fb}^{-1}$, first observations are made of the
suppressed ADS modes $B^{\pm}\to \pi^{\pm} K^{\mp}\pi^+\pi^-_D K^{\pm}$ and
$B^{\pm}\to \pi^{\pm} K^{\mp} \pi^+\pi^- _D\pi^{\pm}$ with a significance of
$5.1\sigma$ and greater than $10\sigma$, respectively. Measurements of CP
asymmetries and CP-conserving ratios of partial widths from this family of
decays are also performed. The magnitude of the ratio between the suppressed
and favoured $B^{\pm}\to DK^{\pm}$ amplitudes is determined to be $r^K_B =
0.097 \pm{0.011}$.
Phys. Rev. D 87, 071103(R) (2013) The decay $B_c^+ \to \psi(2S)\pi^+$ with $\psi(2S) \to \mu^+\mu^-$ is
observed with a significance of $5.2\,\sigma$ using $pp$ collision data
corresponding to an ...integrated luminosity of $1.0\,\invfb$ collected by the
LHCb experiment. The branching fraction of $B_c^+ \to \psi(2S)\pi^+$ decays
relative to that of the $B_c^+ \to J/\psi\pi^+$ mode is measured to be
\begin{equation*} \frac{\mathcal{B}(B_c^+ \to \psi(2S)\pi^+)}{\mathcal{B}(B_c^+
\to J/\psi\pi^+)} = 0.250 \pm 0.068 \,\text{stat} \pm 0.014 \,\text{\syst} \pm
0.006 \,(\mathcal{B}). \end{equation*} The last term is the uncertainty on the
ratio $\mathcal{B}(\psi(2S) \to \mu^+\mu^-)/\mathcal{B}(J/\psi \to
\mu^+\mu^-)$.
Phys. Rev. Lett. 110, 211801 (2013) \noindent A search for the decays $B^0_{s}\rightarrow \mu^+ \mu^- \mu^+
\mu^-$ and $B^0 \rightarrow \mu^+ \mu^- \mu^+ \mu^-$ is performed using data,
corresponding ...to an integrated luminosity of
1.0\ensuremath{\{\,fb}^{-1}}\xspace, collected with the LHCb detector in 2011.
The number of candidates observed is consistent with the expected background
and, assuming phase-space models of the decays, limits on the branching
fractions are set: \{${\ensuremath{\cal B}\xspace}(B^0_{s}\rightarrow \mu^+
\mu^- \mu^+ \mu^-) < 1.6 \ (1.2) \times 10^{-8}$} and \{${\ensuremath{\cal
B}\xspace}(B^0 \rightarrow \mu^+ \mu^- \mu^+ \mu^-)< 6.6 \ (5.3) \times
10^{-9}$} at 95\,% (90\,%) confidence level. In addition, limits are set in the
context of a supersymmetric model which allows for the $B^0_{(s)}$ meson to
decay into a scalar ($S$) and pseudoscalar particle ($P$), where $S$ and $P$
have masses of 2.5 GeV and 214.3 MeV, respectively, both resonances decay into
$\mu^+\mu^-$. The branching fraction limits for these decays are
\{${\ensuremath{\cal B}\xspace}(\ensuremath{B^0_{s}\rightarrow SP}\xspace) <
1.6 \ (1.2) \times 10^{-8}$} and \{${\ensuremath{\cal
B}\xspace}(\ensuremath{B^0\rightarrow SP}\xspace)< 6.3 \ (5.1) \times 10^{-9}$}
at 95% (90%) confidence level.
