First Search for the Flavor Changing Neutral Current Decay D^0 -> gamma gamma

TL;DR

This paper reports a search for the rare decay D^0 -> gamma gamma using data from the CLEO detector, setting upper limits on its branching fraction due to no significant signal being observed.

Contribution

First experimental search for the D^0 -> gamma gamma decay, establishing upper limits on its branching fraction and constraining new physics models.

Findings

No significant signal detected for D^0 -> gamma gamma

Set upper limit on Br(D^0 -> gamma gamma) < 2.9 x 10^{-5}

Established constraints on flavor changing neutral currents in charm decays

Abstract

Using 13.8 fb^{-1} of data collected at or just below the \Upsilon(4S) with the CLEO detector, we report the result of a search for the flavor changing neutral current process D^{0} \to \gamma\gamma. We observe no significant signal for this decay mode and determine 90% confidence level upper limits on the branching fractions Br(D^{0}\to \gamma\gamma)/Br(D^{0}\to\pi^{0}\pi^{0}) < 0.033 and Br(D^{0}\to\gamma\gamma) < 2.9 \times 10^{-5}.''