Measurement ofB→K*γBranching Fractions and Charge Asymmetries

The branching fractions of the exclusive decays ${B}^{0}\ensuremath{\rightarrow}{K}^{*0}\ensuremath{\gamma}$ and ${B}^{+}\ensuremath{\rightarrow}{K}^{*+}\ensuremath{\gamma}$ are measured from a sample of $(22.74\ifmmode\pm\else\textpm\fi{}0.36)\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ decays collected with the BABAR detector at the PEP-II asymmetric ${e}^{+}{e}^{\ensuremath{-}}$ collider. We find $B({B}^{0}\ensuremath{\rightarrow}{K}^{*0}\ensuremath{\gamma})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}[4.23\ifmmode\pm\else\textpm\fi{}0.40(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.22(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $B({B}^{+}\ensuremath{\rightarrow}{K}^{*+}\ensuremath{\gamma})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}[3.83\ifmmode\pm\else\textpm\fi{}0.62(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.22(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and constrain the $\mathrm{CP}$-violating charge asymmetry to be $\ensuremath{-}0.170l{A}_{\mathrm{CP}}(B\ensuremath{\rightarrow}{K}^{*}\ensuremath{\gamma})l0.082$ at $90%$ C.L.