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

Abstract

Using the latest LHCb measurements of time-dependent CPviolation in the B0s→K+K−decay, aU-spinrelation between the decay amplitudes of B0s→K+K−and B0→π+π−decay processes allows constraints to be placed on the angle γof the unitarity triangle and on the B0smixing 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-spinbreaking is studied. At 68% probability, the value γ=(63.5+7.2−6.7)◦modulo180◦is determined. In an alternative analysis, the value −2βs=−0.12+0.14−0.16radis found. In both measurements, the uncertainties due to U-spinbreaking effects up to 50% are included