Measurement of the $\overrightarrow{B}{K}^{*}\gamma$ branching fractions and asymmetries

We report measurements of the radiative decay $\overrightarrow{B}{K}^{*}\gamma .$ The analysis is based on a data sample containing $85.0\times {10}^6$ B meson pairs collected by the Belle detector at the KEKB storage ring. We measure branching fractions of $\mathcal{B}{(B}^0\to K^{*0}\gamma )=(4.01\mathrm{}\pm 0.21\pm 0.17)\times {10}^{-5}$ and $\mathcal{B}{(B}^{+}\to K^{*+}\gamma )=(4.25\mathrm{}\pm 0.31\pm 0.24)\times {10}^{-5},$ where the first and second errors are statistical and systematic, respectively. The isospin asymmetry between $B^0$ and $B^{+}$ decay widths is measured to be ${\Delta }_{0+}=+0.012\mathrm{}\pm 0.044\pm 0.026,$ assuming an equal production rate for $B^0{B}^0$ and $B^{+}{B}^{-}$ pairs from the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance. We search for a partial rate asymmetry between $\mathrm{CP}$ conjugate modes, and find $A_{\mathrm{CP}}\left(\overrightarrow{B}{K}^{*}\gamma \right)=-0.015\pm 0.044\pm \mathrm{0.012.}$