Measurement of the ratio of branching fractions B(B0→K ^*0γ)/B(Bs0→φγ)

The ratio of branching fractions of the radiative B decays B0→K ^*0γ and B0s→φγ has been measured using 0.37fb ^-1 of pp collisions at a center of mass energy of √s=7TeV, collected by the LHCb experiment. The value obtained is B(B0→K ^*0γ)B(B0s→φγ)=1.12±0.08- 0.04-0.08+0.06+0.09, where the first uncertainty is statistical, the second systematic, and the third is associated with the ratio of fragmentation fractions f _s/f _d. Using the world average for B(B0→K ^*0γ)=(4.33±0.15)×10 ^-5, the branching fraction B(B0s→φγ) is measured to be (3.9±0.5)×10 ^-5, which is the most precise measurement to date.