Universality of nonperturbative QCD effects in radiative B-decays
  We demonstrate, by an explicit one-loop calculation, that at leading twist the nonperturbative effects in B -> gamma l nu, B -> gamma gamma and B -> gamma l+ l- radiative decays are contained in a common multiplicative factor (\Lambda_B(E_\gamma), where E_\gamma is the energy of the photon). We argue that this result holds also at higher orders. Ratios of the amplitudes for these processes do not depend on scales below the mass of the B-meson (M_B), and can be calculated as perturbative series in \alpha_s(M_B) 
S. Descotes-Genon (LPT-Orsay and Southampton U.) and C.T. Sachrajda   (Southampton U.)