The Rare Decay D^0 -> gamma gamma

Abstract

We present a calculation of the rare decay mode D^0 -> gamma gamma, in which the long distance contributions are expected to be dominant. Using the Heavy Quark Chiral Perturbation Theory Lagrangian with a strong g coupling as recently determined by CLEO from the D^* -> D pi width, we consider both the anomaly contribution which relates to the annihilation part of the weak Lagrangian and the one-loop pi, K diagrams. The loop contributions which are proportional to g and contain the a_1 Wilson coefficient are found to dominate the decay amplitude, which turns out to be mainly parity violating. The branching ratio is then calculated to be (1.0+-0.5)x10^(-8). Observation of an order of magnitude larger branching ratio could be indicative of new physics.

16 pages, 5 figures, additional reference and several remarks added, results unchanged

References in corpus (4)

• $c\to u\gamma$ in the minimal supersymmetric standard model
• Search for CP Violation in $D^0\to K_S^0{\pi }^0$, $D^0\to {\pi }^0{\pi }^0$ and $D^0\to K_S^0{K}_S^0$
• Study of Radiative Leptonic D Meson Decays
• Nonfactorizable contributions to the decay mode D^0 -> K^0 \bar{K^0}

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• $CP$ violation in $D$ meson decays at Belle