Search for the Radiative DecaysB→ργandB0→ωγ

A search of the exclusive radiative decays $B\to \rho (770)\gamma$ and $B^0\to \omega (782)\gamma$ is performed on a sample of about $84\times {10}^6$ $B\overline{B}$ events collected by the BABAR detector at the SLAC PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage ring. No significant signal is seen in any of the channels. We set upper limits on the branching fractions $\mathcal{B}$ of $\mathcal{B}(B^0\to {\rho }^0\gamma )<1.2\times {10}^{-6}$, $\mathcal{B}(B^{+}\to {\rho }^{+}\gamma )<2.1\times {10}^{-6}$, and $\mathcal{B}(B^0\to \omega \gamma )<1.0\times {10}^{-6}$ at 90% confidence level (C.L.). Using the assumption that $\Gamma (B\to \rho \gamma )=\Gamma (B^{+}\to {\rho }^{+}\gamma )=2\times \Gamma (B^0\to {\rho }^0\gamma )$, we find the combined limit $\mathcal{B}(B\to \rho \gamma )<1.9\times {10}^{-6}$, corresponding to $\mathcal{B}(B\to \rho \gamma )/\mathcal{B}(B\to K^{*}\gamma )<0.047$ at 90% C.L.