Determination of γ and −2βs−2βs from charmless two-body decays of beauty mesons

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−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−2βs. Results from an extended approach, which uses additional inputs on B0→π0π0B0→π0π0 and B+→π+π0B+→π+π0 decays 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.