First search for the flavor changing neutral current decay D-0 -> gamma gamma

Abstract

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