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

TL;DR

This paper reports a search for the rare decay D0 -> gamma gamma and measures the branching fraction of D0 -> pi0 pi0 using data from the BABAR detector, setting an upper limit on the rare decay and providing a precise measurement for the more common decay.

Contribution

The study provides the first upper limit on the branching fraction of D0 -> gamma gamma and a precise measurement of D0 -> pi0 pi0 branching fraction.

Findings

Upper limit on B(D0 -> gamma gamma) < 2.2 x 10^-6 at 90% CL

Measured B(D0 -> pi0 pi0) = (8.4 ± 0.1 ± 0.4 ± 0.3) x 10^-4

Data collected from 470.5 fb^-1 at BABAR detector

Abstract

We search for the rare decay of the $D^{0}$ meson to two photons, $D^0 \rightarrow \gamma \gamma$, and present a measurement of the branching fraction for a $D^0$ meson decaying to two neutral pions, ${B}(D^0 \rightarrow \pi^0 \pi^0)$. 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, ${B}(D^0 \rightarrow \gamma \gamma) < 2.2 \times 10^{-6}$, at 90% confidence level, and find ${B}(D^0 \rightarrow \pi^0 \pi^0) = (8.4 \pm 0.1 \pm 0.4 \pm 0.3) \times 10^{-4}$.