Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)

TL;DR

This paper reports a precise measurement of the ratio of branching fractions for two radiative B meson decays using LHCb data, providing improved understanding of these rare processes.

Contribution

The paper presents the first measurement of the ratio of branching fractions for B0 -> K*0 gamma and Bs0 -> phi gamma decays with unprecedented precision.

Findings

Measured ratio BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- uncertainties

Derived BR(Bs0 -> phi gamma) = (3.9 +/- 0.5) x 10^{-5}

Most precise measurement of BR(Bs0 -> phi gamma) to date

Abstract

The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08 ^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical, the second systematic and the third is associated to the ratio of fragmentation fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/- 0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be (3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.