Search for the Decay D0 -> gamma gamma and Measurement of the Branching Fraction for D0 -> pi0 pi0

Abstract

We search for the rare decay of the $D^0$ meson to two photons, $D^0\to {\hat{I}}^3{\hat{I}}^3$, and present a measurement of the branching fraction for a $D^0$ meson decaying to two neutral pions, $B(D^0\to \ddot{I}{€}^0\ddot{I}{€}^0)$. The data sample analyzed corresponds to an integrated luminosity of 470.5 {\sl B {-0.4em} {\small\sl A} {-0.37em} \sl B {-0.4em} {\small\sl A {-0.02em}R}} detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at SLAC. We place an upper limit on the branching fraction for the decay of a $D^0$ meson to two photons, $B(D^0\to {\hat{I}}^3{\hat{I}}^3)<2.2\times 10^{-6}$, at 90% confidence level, and find $B(D^0\to \ddot{I}{€}^0\ddot{I}{€}^0)=(8.4\pm 0.1\pm 0.4\pm 0.3)\times 10^{-4}$.

8 pages, 3 postscript figures, submitted to Physical Revew D - Rapid Communications