Supersymmetric Effects on Isospin Symmetry Breaking and Direct CP Violation in B → ργ

We argue that one can search for physics beyond the standard model through measurements of the isospin-violating quantity � −0 ≡ ( B − → ρ − γ)/2( B 0 → ρ 0 γ)−1, its charge conjugate � +0 , and direct CP violation in the partial decay rates of B ± → ρ ± γ. We illustrate this by working out theoretical profiles of the charge-conjugate averaged ratio � ≡ 1 (� +0 + � −0 ) and the CP asymmetry ACP(B ± → ρ ± γ) in the standard model and in some variants of the minimal supersymmetric standard model. We find that chargino contributions in the large tan β region may modify ¯ (t)