This Letter reports a measurement of the CP violation observables S_J/{\psi}KS0 and C_J/{\psi}KS0 in the decay channel B0 -> J/{\psi} KS0 performed with 1.0/fb of pp collisions at sqrt(s) = 7 TeV ...collected by the LHCb experiment. The fit to the data yields S_J/{\psi}KS0 = 0.73 +- 0.07 (stat) +- 0.04 (syst) and C_J/{\psi}KS0 = 0.03 +- 0.09 (stat) +- 0.01 (syst). Both values are consistent with the current world averages and within expectations from the Standard Model.
Production cross-sections of prompt charm mesons are measured with the first data from \(pp\) collisions at the LHC at a centre-of-mass energy of \(13\,\mathrm{TeV}\). The data sample corresponds to ...an integrated luminosity of \(4.98 \pm 0.19\,\mathrm{pb}^{-1}\) collected by the LHCb experiment. The production cross-sections of \(D^{0}\), \(D^{+}\), \(D_{s}^{+}\), and \(D^{*+}\) mesons are measured in bins of charm meson transverse momentum, \(p_{\mathrm{T}}\), and rapidity, \(y\), and cover the range \(0 < p_{\mathrm{T}} < 15\,\mathrm{GeV}/c\) and \(2.0 < y < 4.5\). The inclusive cross-sections for the four mesons, including charge conjugation, within the range of \(1 < p_{\mathrm{T}} < 8\,\mathrm{GeV}/c\) are found to be \begin{equation} \sigma(pp \to D^{0} X) = 2072 \pm 2 \pm 124\,\mu\mathrm{b}\\ \sigma(pp \to D^{+} X) = 834 \pm 2 \pm \phantom{1}78\,\mu\mathrm{b}\\ \sigma(pp \to D_{s}^{+} X) = 353 \pm 9 \pm \phantom{1}76\,\mu\mathrm{b}\\ \sigma(pp \to D^{*+} X) = 784 \pm 4 \pm \phantom{1}87\,\mu\mathrm{b} \end{equation} where the uncertainties are due to statistical and systematic uncertainties, respectively.
The ratio of branching fractions \(R_{K/\pi} \equiv \mathcal{B}(B_{c}^{+} \to J/\psi K^{+})/\mathcal{B}(B_{c}^{+} \to J/\psi\pi^{+})\) is measured with \(pp\) collision data collected by the LHCb ...experiment at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of 3\({\mbox{fb}^{-1}}\). It is found to be \( R_{K/\pi} = 0.079\pm0.007\pm0.003\), where the first uncertainty is statistical and the second is systematic. This measurement is consistent with the previous LHCb result, while the uncertainties are significantly reduced.
Using proton-proton collision data collected by the LHCb experiment at sqrt(s) = 7 TeV, corresponding to an integrated luminosity of 1.0 fb^{-1}, the ratio of branching fractions of the B0 -> D*- pi+ ...pi- pi+ decay relative to the B0 -> D*- pi+ decay is measured to be B(B0 -> D*- pi+ pi- pi+) / B(B0 -> D*- pi+) = 2.64 \pm 0.04 (stat.) \pm 0.13 (syst.). The Cabibbo-suppressed decay B0 -> D*- K+ pi- pi+ is observed for the first time and the measured ratio of branching fractions is B(B0 -> D*- K+ pi- pi+) / B(B0 -> D*- pi+ pi- pi+) = (6.47 \pm 0.37 (stat.) \pm 0.35 (syst.)) x 10^{-2}. A search for orbital excitations of charm mesons contributing to the B0 -> D*- pi+ pi- pi+ final state is also performed, and the first observation of the B0 -> Dbar_{1}(2420)^0 pi+ pi- decay is reported with the ratio of branching fractions B(B0 -> (Dbar_{1}(2420)^0 -> D*- pi+) pi- pi+) / B(B0 -> D*- pi+ pi- pi+) = (2.04 \pm 0.42 (stat.) \pm 0.22 (syst.)) x 10^{-2}, where the numerator represents a product of the branching fractions B(B0 -> Dbar_{1}(2420)^0 pi- pi+) and B(Dbar_{1}(2420)^0 -> D*- pi+).
The production of \(J/\psi\) mesons in proton-proton collisions at a centre-of-mass energy of \(\sqrt{s}=13\) TeV is studied with the \lhcb detector. Cross-section measurements are performed as a ...function of the transverse momentum \(p_\mathrm{T}\) and the rapidity \(y\) of the \(J/\psi\) meson in the region \(p_\mathrm{T}<14\mathrm{GeV}/c\) and \(2.0<y<4.5\), for both prompt \(J/\psi\) mesons and \(J/\psi\) mesons from \(b\)-hadron decays. The production cross-sections integrated over the kinematic coverage are \(15.03\pm 0.03\pm 0.94\) \(\mu\)b for prompt \(J/\psi\) and \(2.25\pm 0.01\pm 0.14\) \(\mu\)b for \(J/\psi\) from \(b\)-hadron decays, assuming zero polarization of the \(J/\psi\) meson. The first uncertainties are statistical and the second systematic. The cross-section reported for \(J/\psi\) mesons from \(b\)-hadron decays is used to extrapolate to a total \(b\bar{b}\) cross-section. The ratios of the cross-sections with respect to \(\sqrt{s}=8\) TeV are also determined.
The decay B0 -> D K*0 and the charge conjugate mode are studied using 1.0fb-1 of pp collision data collected by the LHCb experiment at sqrt(s) = 7TeV in 2011. The CP asymmetry between the B0 -> D K*0 ...and the B0bar -> D K*0bar decay rates, with the neutral D meson in the CP-even final state K+K-, is found to be A_d_KK = -0.45 +- 0.23 +- 0.02, where the first uncertainty is statistical and the second is systematic. In addition, favoured B0 -> D K*0 decays are reconstructed with the D meson in the non-CP eigenstate K+ pi-. The ratio of the B-flavour averaged decay rates in D decays to CP and non-CP eigenstates is measured to be R_d_KK = 1.36 (+0.37) (-0.32) +- 0.07, where the ratio of the branching fractions of D0 -> K- pi+ to D0 -> K+ K- decays is included as multiplicative factor. The CP asymmetries measured with two control channels, the favoured B0 -> DK*0 decay with D -> K+ pi- and the Bs0bar -> D K*0 decay with D K+ K-, are also reported.
We report a measurement of the time-dependent ratio of D0->K+pi- to D0->K-pi+ decay rates in D*+-tagged events using 1.0 fb^{-1} of integrated luminosity recorded by the LHCb experiment. We measure ...the mixing parameters x'2=(-0.9+-1.3)x10^{-4}, y'=(7.2+-2.4)x10^{-3} and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates R_D=(3.52+-0.15)x10^{-3}, where the uncertainties include statistical and systematic sources. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of D0-D0bar oscillations from a single measurement.
The quantum numbers of the X(3872) meson are determined to be JPC = 1++ based on angular correlations in B+ to X(3872) K+ decays, where X(3872) to pi+pi- J/psi and J/psi to \mu+\mu-. The data ...correspond to 1.0 fb-1 of pp collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements, JPC=2-+, is rejected with a confidence level equivalent to more than eight Gaussian standard deviations using the likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X(3872) state.
A measurement of the differential branching fraction of the decay \({B^{0}\rightarrow K^{\ast}(892)^{0}\mu^{+}\mu^{-}}\) is presented together with a determination of the S-wave fraction of the ...\(K^+\pi^-\) system in the decay \(B^{0}\rightarrow K^{+}\pi^{-}\mu^{+}\mu^{-}\). The analysis is based on \(pp\)-collision data corresponding to an integrated luminosity of 3\,fb\(^{-1}\) collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, \(q^2\). Precise theoretical predictions for the differential branching fraction of \(B^{0}\rightarrow K^{\ast}(892)^{0}\mu^{+}\mu^{-}\) decays are available for the \(q^2\) region \(1.1<q^2<6.0\,{\rm GeV}^2/c^4\). In this \(q^2\) region, for the \(K^+\pi^-\) invariant mass range \(796 < m_{K\pi} < 996\,{\rm MeV}/c^2\), the S-wave fraction of the \(K^+\pi^-\) system in \(B^{0}\rightarrow K^{+}\pi^{-}\mu^{+}\mu^{-}\) decays is found to be \begin{equation*} F_{\rm S} = 0.101\pm0.017({\rm stat})\pm0.009 ({\rm syst}), \end{equation*} and the differential branching fraction of \(B^{0}\rightarrow K^{\ast}(892)^{0}\mu^{+}\mu^{-}\) decays is determined to be \begin{equation*} {\rm d}\mathcal{B}/{\rm d} q^2 = (0.342_{\,-0.017}^{\,+0.017}({\rm stat})\pm{0.009}({\rm syst})\pm0.023({\rm norm}))\times 10^{-7}c^{4}/{\rm GeV}^{2}. \end{equation*} The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions.