Measurement of the ratio of branching fractions B(B0→K*0γ)/B(Bs0→φγ) and the direct CP asymmetry in B 0→K *0γ

Abstract

The ratio of branching fractions of the radiative B decays B 0→K *0γ and Bs0→φγ has been measured using an integrated luminosity of 1.0 fb -1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s=7 TeV. The value obtained isB(B0→K*0γ)B(Bs0→φγ)=1.23±0.06 (stat.)±0.04 (syst.)±0.10(fs/fd), where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions f s/f d. Using the world average value for B(B0→K*0γ), the branching fraction B(Bs0→φγ) is measured to be (3.5±0.4)×10 -5.The direct CP asymmetry in B 0→K *0γ decays has also been measured with the same data and found to beACP(B0→K*0γ)=(0.8±1.7 (stat.)±0.9 (syst.))%.Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations. © 2012 CERN.