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Register a new userMeasurement of branching fractions of charmless four-body $Lambda_b^0$ and $Xi_b^0$ decays
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A search for charmless four-body decays of $Lambda_{b}^{0}$ and $Xi_{b}^{0}$ baryons with a proton and three charged mesons (either kaons or pions) in the final state is performed. The data sample used was recorded in 2011 and 2012 with the LHCb experiment and corresponds to an integrated luminosity of 3 fb$^{-1}$. Six decay modes are observed, among which $Lambda_{b}^{0} to pK^{-}pi^{+}pi^{-}$, $Lambda_{b}^{0} to pK^{-}K^{+}K^{-}$, $Xi_{b}^{0} to pK^{-}pi^{+}pi^{-}$ and $Xi_{b}^{0} to pK^{-} pi^{+}K^{-}$ are established for the first time. Their branching fractions (including the ratio of hadronisation fractions in the case of the $Xi_{b}^{0}$ baryon) are determined relative to the $Lambda_{b}^{0} to Lambda_{c}^{+}pi^{-}$ decay.
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A search for $CP$ violation in charmless four-body decays of $Lambda_b$ and $Xi_b^0$ baryons with a proton and three charged mesons in the final state is performed. To cancel out production and detection charge-asymmetry effects, the search is carried out by measuring the difference between the $CP$ asymmetries in a charmless decay and in a decay with an intermediate charmed baryon with the same particles in the final state. The data sample used was recorded in 2011 and 2012 with the LHCb detector and corresponds to an integrated luminosity of $3 {rm fb}^{-1}$. A total of 18 $CP$ asymmetries are considered, either accounting for the full phase space of the decays or exploring specific regions of the decay kinematics. No significant $CP$-violation effect is observed in any of the measurements.
Bottom baryons decaying to a J/psi meson and a hyperon are reconstructed using 1.0 fb^{-1} of data collected in 2011 with the LHCb detector. Significant Lambda_b^0 rightarrow J/psi Lambda, Xi_b^-rightarrow J/psi Xi^- and Omega_b^- rightarrow J/psi Omega^- signals are observed and the corresponding masses are measured to be M(Lambda_b^0) = 5619.53 pm 0.13 (stat) pm 0.45 (syst) MeV/c^2, M(Xi_b^-) = 5795.8 pm 0.9 (stat) pm 0.4 (syst) MeV/c^2, M(Omega_b^-) = 6046.0 pm 2.2 (stat) pm 0.5 (syst) MeV/c^2, while the differences with respect to the Lambda_b^0 mass are M(Xi_b^-)-M(Lambda_b^0) = 176.2 pm 0.9 (stat) pm 0.1 (syst) MeV/c^2, M(Omega_b^-)-M(Lambda_b^0) = 426.4 pm 2.2 (stat) pm 0.4 (syst) MeV/c^2. These are the most precise mass measurements of the Lambda_b^0, Xi_b^- and Omega_b^- baryons to date. Averaging the above Lambda_b^0 mass measurement with that published by LHCb using 35 pb^{-1} of data collected in 2010 yields M(Lambda_b^0) = 5619.44 pm 0.13 (stat) pm 0.38 (syst) MeV/c^2.
Based on data corresponding to an integrated luminosity of 0.37 fb^-1 collected by the LHCb experiment in 2011, the following ratios of branching fractions are measured: B(B0 -> pi+ pi-) / B(B0 -> K+pi-) = 0.262 +/- 0.009 +/- 0.017, (fs/fd) * B(Bs -> K+K-) / B(B^0 -> K+pi-) = 0.316 +/- 0.009 +/- 0.019, (fs/fd) * B(Bs ->pi+ K-) / B(B0 -> K+pi-) = 0.074 +/- 0.006 +/- 0.006, (fd/fs) * B(B0 -> K+K-) / B(Bs -> K+K-) = 0.018 {+ 0.008 - 0.007} +/- 0.009, (fs/fd) * B(Bs -> pi+pi-) / B(B0 -> pi+pi-) = 0.050 {+ 0.011 - 0.009} +/- 0.004, B(Lambda_b -> p pi-) / B(Lambda_b -> p K-) = 0.86 +/- 0.08 +/- 0.05, where the first uncertainties are statistical and the second systematic. Using the current world average of B(B0 -> K+pi-) and the ratio of the strange to light neutral B meson production fs/fd measured by LHCb, we obtain: B(B0 -> pi+pi-) = (5.08 +/- 0.17 +/- 0.37) x 10^-6, B(Bs -> K+K-) = (23.0 +/- 0.7 +/- 2.3) x 10^-6, B(Bs -> pi+K-) = (5.4 +/- 0.4 +/- 0.6) x 10^-6, B(B0 -> K+K-) = (0.11 {+ 0.05 - 0.04} +/- 0.06) x 10^-6, B(Bs -> pi+pi-) = (0.95 {+ 0.21 - 0.17} +/- 0.13) x 10^-6. The measurements of B(Bs -> K+K-), B(Bs -> pi+ K-) and B(B0 -> K+K-) are the most precise to date. The decay mode Bs -> pi+pi- is observed for the first time with a significance of more than 5 sigma.
Using a data sample of 980 ${rm fb}^{-1}$ of $e^+e^-$ annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we report the results of a study of the decays of the $Omega_c^0$ charmed baryon into hadronic final states. We report the most precise measurements to date of the relative branching fractions of the $Omega_c^0$ into $Omega^-pi^+pi^0$, $Omega^-pi^+pi^-pi^+$, $Xi^-K^-pi^+pi^+$, and $Xi^0K^-pi^+$, as well as the first measurements of the branching fractions of the $Omega_c^0$ into $Xi^-bar{K}^0pi^+$, $Xi^0bar{K}^0$, and $Lambda bar{K}^0bar{K}^0$, all with respect to the $Omega^-pi^+$ decay. In addition, we investigate the resonant substructure of these modes. Finally, we present a limit on the branching fraction for the decay $Omega_c^0toSigma^+K^-K^-pi^+$.
Using 482 pb$^{-1}$ of data taken at $sqrt{s}=4.009$ GeV, we measure the branching fractions of the decays of $D^{*0}$ into $D^0pi^0$ and $D^0gamma$ to be $BR(D^{*0} to D^0pi^0)=(65.5pm 0.8pm 0.5)%$ and $BR(D^{*0} to D^0gamma)=(34.5pm 0.8pm 0.5)%$ respectively, by assuming that the $D^{*0}$ decays only into these two modes. The ratio of the two branching fractions is $BR(D^{*0} to D^0pi^0)/BR(D^{*0} to D^0gamma) =1.90pm 0.07pm 0.05$, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of three compared to the present world average values.
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