Measurements of Branching Fraction and Polarization in B^+ -> rho^+ K^{*0} Decay

Abstract

We present the results of a study of the charmless vector-vector decay $B^{+}\to {\rho }^{+}{K}^{\ast 0}$, based on 253 fb${}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We obtain the branching fraction $\mathcal{B}(B^{+}\to {\rho }^{+}{K}^{\ast 0})=(8.9\pm 1.7(\mathrm{stat})\pm 1.2(\mathrm{syst}))\times 10^{-6}$. We also perform a helicity analysis of the $\rho$ and $K^{\ast }$ vector mesons, and obtain the longitudinal polarization fraction $f_L(B^{+}\to {\rho }^{+}{K}^{\ast 0})=0.43\pm 0.11(\mathrm{stat}{)}_{-0.02}^{+0.05}(\mathrm{syst})$.

5 pages, 3 figures