Determination of gamma from charmless B^+/- -> M^0 M^+/- decays using U-spin

Abstract

U-spin multiplet approach is applied to the full set of charmless hadronic B+/- --> M0 M+/- decays for the purpose of precise extraction of the unitarity angle gamma. 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 yield a precise value of gamma. The crucial advantage of this method over the common SU(3) symmetry based quark-diagrammatic approach 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 related to the neglect of some topological diagrams (e.g., exchange and annihilation graphs) in the SU(3) approach. Application of the U-spin approach to the current data yields: gamma=54^{+12}_{-11} degrees. We find that improved measurements of phi pi+/- and K*0bar K+/- branching ratios would lead to appreciably better extraction of gamma. 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).

Comments: 5 pages; minor changes, further clarification on key differences with the SU(3) approach; added references