Enhanced electroweak penguin amplitude in B-->VV decays

Abstract

We discuss a novel electromagnetic penguin contribution to the transverse helicity amplitudes in B decays to two vector mesons, which is enhanced by two powers of mB/Lambda relative to the standard penguin amplitudes. This leads to unique polarization signatures in penguin-dominated decay modes such as B-->rho K* similar to polarization effects in the radiative decay B-->K*gamma, and offers new opportunities to probe the magnitude and chirality of flavour-changing neutral current couplings to photons.