No Arabic abstract
We report recent results obtained with the Belle detector using a 23.6 fb^{-1} data sample collected on the Y(5S) resonance at the KEKB asymmetric energy e^+ e^- collider. Inclusive semileptonic B_s^0 -> X^+ l^- u decays are studied for the first time and the branching fraction is measured. Combining the electron and muon channels, we obtain Bf(B_s^0 -> X^+ l^- u) = (10.2 pm 0.8 pm 0.9)%. Also, the radiative penguin decay B_s^0 -> phi gamma is observed for the first time, and an improved upper limit for the decay B_s^0 to gamma gamma is obtained.
Recent results obtained using the data sample of 23.6 fb^-1 collected on the Y(5S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider are discussed. Measurements of several B_s^0 decay branching fractions are reported. Studies of the Y(5S) decays to the channels with B^+ and B^0 mesons or bottomonium states are discussed.
We present an analysis of the semi-inclusive decays $B_s to D_s^- X ell^+ u$ and $B_s to D_s^{*-} X ell^+ u$, where $X$ denotes a final state that may consist of additional hadrons or photons and $ell$ is an electron or muon. The studied $B_s$ decays are contained in the $121.4~{rm fb}^{-1}$ $Upsilon(5S)$ data sample collected by the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching fractions of the decays are measured to be $mathcal{B}(B_s to D_s^- X ell^+ u) = [8.2 pm 0.2 (text{stat}) pm 0.6 (text{syst}) pm 1.4 (text{ext})]%$ and $mathcal{B}(B_s to D_s^{*-} X ell^+ u) = [5.4 pm 0.4 (text{stat}) pm 0.4 (text{syst}) pm 0.9 (text{ext})]%$, where the first two uncertainties are statistical and systematic and the last is due to external parameters. The measurement also provides an estimate of the $B_s^{(*)}bar{B}_s^{(*)}$ production cross-section, $sigma(e^+e^- to B_s^{(*)}bar{B}_s^{(*)}) = (53.8 pm 1.4 (text{stat}) pm 4.0 (text{syst}) pm 3.4 (text{ext})),{rm pb}$, at the center-of-mass energy $sqrt{s} = 10.86,{rm GeV}$.
Latest LHCb measurements of $CP$ violation in the interference between mixing and decay are presented based on $pp$ collision data collected during LHC Run I, corresponding to an integrated luminosity of $3.0, {rm fb}^{-1}$. Approximately $27, 000$ $B_s^0to J/psi pi^+pi^-$ signal events are used to make what is at the moment the most precise single measurement of the $CP$-violating phase in $bto cbar{c}s$ transitions, $phi_s^{cbar{c}s}=0.070pm0.068{rm (stat.)}pm0.008{rm (syst.)}$ rad. The most accurate measurement of the $CP$-violating phase in $bto sbar{s}s$ transitions, $phi_s^{sbar{s}s}$, is found from approximately $4, 000$ $B_s^0to phiphi$ signal events to be $phi_s^{sbar{s}s}=-0.17pm{rm (stat.)}0.15pm0.03{rm (syst.)}$ rad.
Rare and flavour-changing neutral current decays of the B meson are an important probe in the search for physics beyond the Standard Model. There have recently been several anomalies in rare B decays, and lepton-universality measurements, specifically involving the $bto sell^+ell^-$ quark transition. These results tend towards a non-Standard-Model interpretation. The Belle II experiment is a next-generation b physics experiment located at SuperKEKB, an upgraded B factory $e^+e^-$ collider, in Tsukuba, Japan. The first collisions are expected in early 2018 with full physics data expected in 2019. This document describes prospects for several rare B decays at Belle II including $bto sell^+ell^-$ processes and others, such as $bto(s,,d)gamma$ and $bto s ubar u$. Areas where the Belle II program is complementary to that of the currently running LHCb experiment are highlighted.
We report measurements of the branching fractions of the decays $Lambda^+_ctoSigma^+pi^-pi^+$, $Lambda^+_ctoSigma^0pi^+pi^0$ and $Lambda^+_ctoSigma^+pi^0pi^0$ relative to the reference channel $Lambda^+_cto pK^-pi^+$. The analysis is based on the full data sample collected at and close to $Upsilon(4S)$ resonance by the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider corresponding to the integrated luminosity of 711 fb$^{-1}$. We measure ${cal B}(Lambda^+_crightarrowSigma^+pi^-pi^+)/{cal B}(Lambda^+_cto pK^-pi^+) = 0.706~pm 0.003~pm 0.029$, ${cal B}(Lambda^+_crightarrowSigma^0pi^+pi^0)/{cal B}(Lambda^+_cto pK^-pi^+) = 0.491~pm 0.005~pm 0.028$ and ${cal B}(Lambda^+_crightarrowSigma^+pi^0pi^0)/{cal B}(Lambda^+_cto pK^-pi^+) = 0.198~pm 0.006~pm 0.016$. The listed uncertainties are statistical and systematic, respectively.