Isospin symmetry breaking and direct CP violation in B -> \rho \gamma within and beyond the standard model

Abstract

We discuss the isospin symmetry breaking quantity \Delta^{\pm 0} = \Gamma(B^\pm -> \rho^\pm \gamma)/[2 \Gamma(B^0 -> \rho^0 \gamma)] - 1, and the direct CP violation in B^\pm -> \rho^\pm \gamma within and beyond the standard model. After showing that the leading-order calculation would be a good approximation in such models, we argue that measurements of these quantities would be able to disentagle physics beyond the standard model.