The charmless three-body decay modes $B^{\pm} \rightarrow K^{\pm} \pi^{+} \pi^{-}$, $B^{\pm} \rightarrow K^{\pm} K^{+} K^{-}$, $B^{\pm} \rightarrow \pi^{\pm} K^{+} K^{-}$ and $B^{\pm} \rightarrow ...\pi^{\pm} \pi^{+} \pi^{-}$ are reconstructed using data, corresponding to an integrated luminosity of 3.0\;$\mbox{\,fb}^{-1}$, collected by the LHCb detector. The inclusive $C\!P$ asymmetries of these modes are measured to be $$ A_{C\!P}(B^{\pm} \rightarrow K^{\pm} \pi^{+} \pi^{-})= +0.025 \pm 0.004 \pm 0.004 \pm 0.007 \\ A_{C\!P}(B^{\pm} \rightarrow K^{\pm} K^{+} K^{-}) = -0.036 \pm 0.004 \pm 0.002 \pm 0.007 \\ A_{C\!P}(B^{\pm} \rightarrow \pi^{\pm} \pi^{+} \pi^{-})= +0.058 \pm 0.008 \pm 0.009 \pm 0.007 \\ A_{C\!P}(B^{\pm} \rightarrow \pi^{\pm} K^{+} K^{-})= -0.123 \pm 0.017 \pm 0.012 \pm 0.007 $$ %% where the first uncertainty is statistical, the second systematic, and the third is due to the $C\!P$ asymmetry of the $B^{\pm} \rightarrow J/\psi K^{\pm}$ reference mode. The distributions of these asymmetries are also studied as functions of position in the Dalitz plot and suggest contributions from rescattering and resonance interference processes.
Measurements of the cross-section for producing \bquark quarks in the reaction \(pp\to b\bar{b} X\) are reported in 7 and 13 TeV collisions at the LHC as a function of the pseudorapidity \(\eta\) in ...the range \(2<\eta<5\) covered by the acceptance of the LHCb experiment. The measurements are done using semileptonic decays of \(b\)-flavored hadrons decaying into a ground-state charmed hadron in association with a muon. The cross-sections in the covered \(\eta\) range are \(72.0\pm 0.3\pm6.8~\mu\)b and \(144\pm 1\pm 21~\mu\)b for 7 and 13 TeV. The ratio is \(2.00\pm0.02\pm0.26\), where the quoted uncertainties are statistical and systematic, respectively. The agreement with theoretical expectation is good at 7 TeV, but differs somewhat at 13 TeV. The measured ratio of cross-sections is larger at lower \(\eta\) than the model prediction.
The resonant substructure of $B_s^0 \rightarrow \overline{D}^0 K^- \pi^+$ decays is studied with the Dalitz plot analysis technique. The study is based on a data sample corresponding to an integrated ...luminosity of $3.0\,{\rm fb}^{-1}$ of $pp$ collision data recorded by LHCb. A structure at $m(\overline{D}^0 K^-) \approx 2.86 {\rm GeV}/c^2$ is found to be an admixture of spin-1 and spin-3 resonances. The masses and widths of these states and of the $D^*_{s2}(2573)^-$ meson are measured, as are the complex amplitudes and fit fractions for all the $\overline{D}^0 K^-$ and $K^-\pi^+$ components included in the amplitude model. In addition, the $D^*_{s2}(2573)^-$ resonance is confirmed to be spin-2.
The first measurement that relates semileptonic and hadronic decay rates of the $B_c^+$ meson is performed using proton-proton collision data corresponding to 1.0 fb$^{-1}$ of integrated luminosity ...collected with the LHCb detector. The measured value of the ratio of branching fractions, ${\cal B}(B_c^+ \to J/\psi \pi^+)/{\cal B}(B_c^+\to J/\psi\mu^+\nu_\mu)=0.0469 \pm 0.0028 (stat.) \pm 0.0046 (syst.)$, is at the lower end of available theoretical predictions.
Measurements of charm mixing and \(C\!P\) violation parameters from the decay-time-dependent ratio of \( D^0 \to K^+ \pi^- \) to \( D^0 \to K^- \pi^+ \) decay rates and the charge-conjugate ratio are ...reported. The analysis uses \(\overline{B}\to D^{*+} \mu^- X\), and charge-conjugate decays, where \(D^{*+}\to D^0 \pi^+\), and \(D^0\to K^{\mp} \pi^{\pm}\). The \(pp\) collision data are recorded by the LHCb experiment at center-of-mass energies \(\sqrt{s}\) = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb\(^{-1}\). The data are analyzed under three hypotheses: (i) mixing assuming \(C\!P\) symmetry, (ii) mixing assuming no direct \(C\!P\) violation in the Cabibbo-favored or doubly Cabibbo-suppressed decay amplitudes, and (iii) mixing allowing either direct \(C\!P\) violation and/or \(C\!P\) violation in the superpositions of flavor eigenstates defining the mass eigenstates. The data are also combined with those from a previous LHCb study of \(D^0\to K \pi\) decays from a disjoint set of \( D^{*+} \) candidates produced directly in \(pp\) collisions. In all cases, the data are consistent with the hypothesis of \(C\!P\) symmetry.
Two new algorithms for use in the analysis of \(pp\) collision are developed to identify the flavour of \(B^0\) mesons at production using pions and protons from the hadronization process. The ...algorithms are optimized and calibrated on data, using \(B^0 \rightarrow D^- \pi^+\) decays from \(pp\) collision data collected by LHCb at centre-of-mass energies of 7 and 8 TeV. The tagging power of the new pion algorithm is 60 % greater than the previously available one; the algorithm using protons to identify the flavour of a \(B^0\) meson is the first of its kind.
The \(CP\) violation observables \(S\) and \(C\) in the decay channel \(B^0 \!\rightarrow D^+ D^-\) are determined from a sample of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, ...collected by the LHCb experiment and corresponding to an integrated luminosity of 3 fb\(^{-1}\). The observable \(S\) describes \(CP\) violation in the interference between mixing and the decay amplitude, and \(C\) parametrizes direct \(CP\) violation in the decay. The following values are obtained from a flavor-tagged, decay-time-dependent analysis: \begin{align*} S &= -0.54 \, ^{+0.17}_{-0.16} \, \text{(stat)} \pm 0.05 \, \text{(syst)}\,,\newline C &= \phantom{-}0.26 \, ^{+0.18}_{-0.17} \, \text{(stat)} \pm 0.02 \, \text{(syst)}\,. \end{align*} These values provide evidence for \(CP\) violation at a significance level of 4.0 standard deviations. The phase shift due to higher-order Standard Model corrections is constrained to a small value of \begin{align*} \Delta\phi = -0.16\,^{+0.19}_{-0.21}\,\text{rad}\,. \end{align*}
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