Measurement of the ratio of branching fractions $\mathcal{B}(B_d\to K^{*0}\gamma)/\mathcal{B}(B_s\to \phi\gamma)$ with the LHCb experiment at $\sqrt{s}=7$~TeV

The ratio of branching ratios of the radiative $B$ decays $B_d\to K^{*0}\gamma$ and $B_s\to \phi\gamma$ has been measured using $340.1$~pb$^{-1}$ of \emph{pp} collisions at a centre of mass energy of $\sqrt{s}=7$~TeV taken with the LHCb detector. The obtained value for the ratio is $ 1.52 \pm 0.14 \mathrm{(stat)} \pm 0.10 \mathrm{(syst)} \pm 0.12 (f_s/f_d)$. Using the HFAG value for $\mathcal{B}(B_d\to K^{*0}\gamma)$, $\mathcal{B}(B_s\to \phi\gamma)$ has been found to be $(2.8 \pm 0.5 )\times 10^{-5}$.