ABSTRACT
We present a measurement of R_{K^{*}}, the branching fraction ratio B(BâK^{*}µ^{+}µ^{-})/B(BâK^{*}e^{+}e^{-}), for both charged and neutral B mesons. The ratio for the charged case R_{K^{*+}} is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass q^{2}. The analysis is based on a data sample of 711 fb^{-1}, containing 772×10^{6} BB[over ¯] events, recorded at the Ï(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The obtained results are consistent with standard model expectations.
ABSTRACT
We report the first observation of the radiative decay of the Ï(1S) into a charmonium state. The significance of the observed signal of Ï(1S)âγχ_{c1} is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[Ï(1S)âγχ_{c1}]=[4.7_{-1.8}^{+2.4}(stat)_{-0.5}^{+0.4}(sys)×10^{-5}]. We also searched for Ï(1S) radiative decays into χ_{c0,2} and η_{c}(1S,2S), and set upper limits on their branching fractions. These results are obtained from a 24.9 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider at a center-of-mass energy equal to the Ï(2S) mass using Ï(1S) tagging by the Ï(2S)âÏ(1S)π^{+}π^{-} transitions.
