Charm Radiative Decays with Neutral Mesons D^0 -> K^0(bar) pi^0 gamma, D^0 -> K^0(bar) eta (eta') gamma

Abstract

The radiative decays D^0 -> K^0(bar) P^0 gamma with nonresonant K^0(bar) P^0 (P^0 = pi^0, eta, eta') are considered within the framework which combines heavy quark effective theory and the chiral Lagrangian. Due to neutral mesons the amplitudes do not have bremsstrahlung contributions. We assume factorization for the weak matrix elements. Light (virtual) vector mesons are found to give the main contribution to the decay amplitudes. The decay D^0 -> K^0(bar) pi^0 gamma is predicted to have a branching ratio of 3 x 10^(-4), with comparable contributions from parity-conserving and parity-violating parts of the amplitude. The decays with eta (eta') in the final state are expected with branching ratios of 1.1 x 10^(-5) and 0.4x10^(-7) respectively and are mainly parity conserving.