Determination of γ and -2βsfrom charmless two-body decays of beauty mesons

Abstract

Using the latest LHCb measurements of time-dependent CP violation in the Bs0→K+K- decay, a U-spin relation between the decay amplitudes of Bs0→K+K- and B0→π+π-decay processes allows constraints to be placed on the angle γ of the unitarity triangle and on the Bs0 mixing phase -2βs. Results from an extended approach, which uses additional inputs on B0→π0π0and B+→π+π0decays from other experiments and exploits isospin symmetry, are also presented. The dependence of the results on the maximum allowed amount of U-spin breaking is studied. At 68% probability, the value γ=(63.5-6.7+7.2)° modulo 180° is determined. In an alternative analysis, the value -2βs=-0.12-0.16+0.14 rad is found. In both measurements, the uncertainties due to U-spin breaking effects up to 50% are included.