A search for CP violation in $Λ_{b}^0 → pK^−$ and $Λ_b ^0 → p π^−$ decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity ...of 3.0 fb$^{−1}$ . The $CP$-violating asymmetries are measured to be $A_{CP}^{pK^−} = −0.020±0.013±0.019$ and $A_{CP}^{pπ^−}=−0.035±0.017±0.020$, and their difference $A_{CP}^{pK^−}−A_{CP}^{pπ^−}=0.014±0.022±0.010$, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date.
Investigations of the existence of pentaquark states containing a single $b$ (anti)quark decaying weakly into four specific final states $J/ψK^+ π^- p, J/ψK^- π^- p, J/ψK^- π^+ p$, and J/ψϕ(1020)p ...are reported. The data sample corresponds to an integrated luminosity of 3.0 fb$^{-1}$ in 7 and 8 TeV pp collisions acquired with the LHCb detector. Signals are not observed and upper limits are set on the product of the production cross section times branching fraction with respect to that of the $Λ_b^0$.
The Cabibbo-suppressed decay Λ$_{b}^{0}$ → ψ(2S)pπ$^{−}$ is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and ...1.9 fb$^{−1}$ of integrated luminosity at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The ψ(2S) mesons are reconstructed in the μ$^{+}$μ$^{−}$ final state. The branching fraction with respect to that of the Λ$_{b}^{0}$ → ψ(2S)pK$^{−}$ decay mode is measured to be
The first observation of the $B_s^0 \to \overline{D}^0 K^+ K^-$ decay is reported, together with the most precise branching fraction measurement of the mode $B^0 \to \overline{D}^0 K^+ K^-$. The ...results are obtained from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3.0~\textrm{fb}^{-1}$. The data were collected with the LHCb detector at centre-of-mass energies of $7$ and $8$ TeV. The branching fraction of the $B^0 \to \overline{D}^0 K^+ K^-$ decay is measured relative to that of the decay $B^0 \to \overline{D}^0 \pi^+ \pi^-$ to be $$\frac{\mathcal{B}(B^0 \to \overline{D}^0 K^+ K^-)}{\mathcal{B}(B^0 \to \overline{D}^0 \pi^+ \pi^-)} = (6.9 \pm 0.4 \pm 0.3)\%,$$ where the first uncertainty is statistical and the second is systematic. The measured branching fraction of the $B_s^0 \to \overline{D}^0 K^+ K^-$ decay mode relative to that of the corresponding $B^0$ decay is $$\frac{\mathcal{B}(B_s^0 \to \overline{D}^0 K^+ K^-)}{\mathcal{B}(B^0 \to \overline{D}^0 K^+ K^-)} = (93.0 \pm 8.9 \pm 6.9)\%.$$ Using the known branching fraction of ${B^0 \to \overline{D}^0 \pi^+ \pi^-}$, the values of ${{\mathcal B}(B^0 \to \overline{D}^0 K^+ K^- )=(6.1 \pm 0.4 \pm 0.3 \pm 0.3) \times 10^{-5}}$, and ${{\cal B}(B_s^0 \to \overline{D}^0 K^+ K^-)=}$ $(5.7 \pm 0.5 \pm 0.4 \pm 0.5) \times 10^{-5}$ are obtained, where the third uncertainties arise from the branching fraction of the decay modes ${B^0 \to \overline{D}^0 \pi^+ \pi^-}$ and $B^0 \to \overline{D}^0 K^+ K^-$, respectively.
The cross-section for inelastic proton-proton collisions at a centre-of-mass energy of 13 TeV is measured with the LHCb detector. The fiducial cross-section for inelastic interactions producing at ...least one prompt long-lived charged particle with momentum p > 2 GeV/c in the pseudorapidity range 2 < η < 5 is determined to be σ$_{acc}$ = 62.2 ± 0.2 ± 2.5 mb. The first uncertainty is the intrinsic systematic uncertainty of the measurement, the second is due to the uncertainty on the integrated luminosity. The statistical uncertainty is negligible. Extrapolation to full phase space yields the total inelastic proton-proton cross-section σ$_{inel}$ = 75.4 ± 3.0 ± 4.5 mb, where the first uncertainty is experimental and the second due to the extrapolation. An updated value of the inelastic cross-section at a centre-of-mass energy of 7 TeV is also reported.
The first measurement of the lifetime of the doubly charmed baryon $\Xi_{cc}^{++}$ is presented, with the signal reconstructed in the final state $Λ_c ^+ K^- π^+ π^+$. The data sample used ...corresponds to an integrated luminosity of 1.7 fb$^{-1}$, collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV. The $\Xi_{cc}^{++}$ lifetime is measured to be $0.256_{-0.022}^{+0.024}(stat)±0.014(syst) ps$.
A search for B$^{+}$ → D$_{s}^{+}$ K$^{+}$K$^{−}$ decays is performed using pp collision data corresponding to an integrated luminosity of 4.8 fb$^{−1}$, collected at centre-of-mass energies of 7, 8 ...and 13 TeV with the LHCb experiment. A significant signal is observed for the first time and the branching fraction is determined to be $\mathcal{B}(B^+ \to D_{s}^+ K^+ K^-) = (7.1\pm 0.5\pm 0.6\pm 0.7) \times 10^{-6}$ where the first uncertainty is statistical, the second systematic and the third due to the uncertainty on the branching fraction of the normalisation mode $B^+ \to D^{+}_s \bar{D}^0$. A search is also performed for the pure annihilation decay $B^+ \to D_{s}^+ \phi$. No significant signal is observed and a limit of $\mathcal{B}(B^+ \to D_{s}^+ \phi) < 4.9 \times 10^{-7} (4.2 \times 10^{-7})$ is set on the branching fraction at 95% (90%) confidence level.
The ratios of the branching fractions of the decays $\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+}$, $\Lambda_{c}^{+} \rightarrow p K^{-} K^{+}$, and $\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+}$ ...with respect to the Cabibbo-favoured $\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+}$ decay are measured using proton-proton collision data collected with the LHCb experiment at a 7 TeV centre-of-mass energy and corresponding to an integrated luminosity of 1.0 fb$^{-1}$: \begin{align*} \frac{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+})}{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})} & = (7.44 \pm 0.08 \pm 0.18)\,\%, \frac{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} K^{+})}{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})} &= (1.70 \pm 0.03 \pm 0.03)\,\%, \frac{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+})}{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})} & = (0.165 \pm 0.015 \pm 0.005 )\,\%, \end{align*} where the uncertainties are statistical and systematic, respectively. These results are the most precise measurements of these quantities to date. When multiplied by the world-average value for $\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})$, the corresponding branching fractions are \begin{align*} \mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+}) &= (4.72 \pm 0.05 \pm 0.11 \pm 0.25) \times 10^{-3}, \mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} K^{+}) &= (1.08 \pm 0.02 \pm 0.02 \pm 0.06) \times 10^{-3}, \mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+}) &= (1.04 \pm 0.09 \pm 0.03 \pm 0.05) \times 10^{-4}, \end{align*} where the final uncertainty is due to $\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})$.
A search for the flavor-changing neutral-current decay $Λ_c^+ → pμ^+ μ^-$ is reported using a data set corresponding to an integrated luminosity of 3.0 fb$^{-1}$ collected by the LHCb Collaboration. ...No significant signal is observed outside of the dimuon mass regions around the $ϕ$ and $ω$ resonances, and an upper limit is placed on the branching fraction of $\mathcal{B}(Λ_c^+ → pμ^+ μ^- ) < 7.7(9.6) × 10^{-8}$ at 90%(95%) confidence level. A significant signal is observed in the $ω$ dimuon mass region for the first time.
The ϒ(1S)μ$^{+}$μ$^{−}$ invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two $ \overline{b} $ quarks, $ {X}_{b\overline{b}b\overline{b}} $ . ...The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies $ \sqrt{s}=7 $ , 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb$^{−1}$. No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the $ {X}_{b\overline{b}b\overline{b}} $ state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range 2.0, 5.0, and the $ {X}_{b\overline{b}b\overline{b}} $ state has rapidity in the range 2.0, 4.5 and transverse momentum less than 15 GeV/c.
