Supersymmetric effects on isospin symmetry breaking and direct CP violation in B -> rho gamma - art. no. 014014

We argue that one can search for physics beyond the standard model through measurements of the isospin-violating quantity Delta (-0) = Gamma (B- --> r ho (-) gamma)/2 Gamma (B-0 --> rho (0) gamma) - 1, its charge conjugate Del ta (+0), and direct CP violation in the partial decay rates of B+/- --> rho (+/-) gamma. We illustrate this by working out theoretical profiles of bot h the charge-conjugate averaged ratio Delta = 1/2 (Delta (+0) + Delta (-0)) and the CP asymmetry A(CP)(B+/- --> rho (+/-) gamma) in the standard model and in some variants of the minimal supersymmetric standard model. We find that chargino contributions in the large tan beta region may modify the ma gnitudes and flip the signs of Delta and A(CP)(B+/- --> rho (+/-) gamma) co mpared to their standard-model values, thereby providing an unmistakable si gnature of supersymmetry.