Radiative leptonicBdecays in the light front model

Within the light front framework, we calculate the form factors for $\overrightarrow{B}\gamma$ transitions directly in the entire physical range of momentum transfer. Using these form factors, we study the radiative decays of $\overrightarrow{B}l{\nu }_l\gamma$ and $B_{s\left(d\right)\mathrm{}}\to \nu \overline{\nu }\gamma$. We show that the decay rates of $\overrightarrow{B}l{\nu }_l\gamma$ $(l=e,\mu )$ and $\overrightarrow{B}\nu \overline{\nu }\gamma$ are larger than that of the corresponding purely leptonic modes. Explicitly, in the standard model, we find that the branching ratios of $\overrightarrow{B}\mu {\nu }_{\mu }\gamma$ and $B_s\to \nu \overline{\nu }\gamma$ are $1.3\times {10}^{-6}$ and $2.0\times {10}^{-8}$, in contrast with $2.3\times {10}^{-7}$ and $0$ for $\overrightarrow{B}\mu {\nu }_{\mu }$ and $\overrightarrow{B}\nu \overline{\nu }$, respectively.