Determination of gamma from Charmless B --> M1 M2 Decays Using U-Spin

Abstract

In our previous paper we applied U-spin symmetry to charmless hadronic B+- --> M0 M+- decays for the purpose of precise extraction of the unitarity angle gamma. In this paper we extend our approach to neutral B0 and Bs --> M1 M2 decays. A very important feature of this method is that no assumptions regarding relative sizes of topological decay amplitudes need to be made. As a result, this method avoids an uncontrollable theoretical uncertainty that is often related to the neglect of some topological diagrams (e.g., exchange and annihilation graphs) in quark-diagrammatic approaches. In charged B+- decays, each of the four data sets, P0 P+-, P0 V+-, V0 P+- and V0 V+-, with P=pseudoscalar and V=vector, can be used to obtain a value of gamma. Among neutral decays, only experimental data in the B0, Bs --> P- P+ subsector is sufficient for a U-spin fit. Application of the U-spin approach to the current charged and neutral B decay data yields: gamma=(80^{+6}_{-8}) degrees. In this method, which is completely data driven, in a few years we should be able to obtain a model independent determination of gamma with an accuracy of O(few degrees).