A Search for the Decay B^0 -> gamma gamma

TL;DR

This paper reports a search for the rare decay B^0 -> gamma gamma using data from the BABAR detector, finding no significant signal and setting an upper limit on its branching fraction.

Contribution

The study provides the first experimental upper limit on the B^0 -> gamma gamma decay branching fraction using a large data sample.

Findings

Observed 21^{+13}_{-12} signal events with 1.9 sigma significance.

Measured branching fraction B(B^0 -> gamma gamma) = (1.7 +- 1.1(stat.) +- 0.2(syst.)) x 10^-7.

Set a 90% confidence level upper limit of B(B^0 -> gamma gamma) < 3.3 x 10^-7.

Abstract

We report the result of a search for the rare decay B^0 -> gamma gamma in 426 fb-1 of data, corresponding to 226 million B^0 \bar{B}^0 pairs, collected on the Upsilon(4S) resonance at the PEP-II asymmetric-energy e+e- collider using the BABAR detector. We use a maximum likelihood fit to extract the signal yield and observe 21^{+13}_{-12} signal events with statistical significance of 1.9 sigma. This corresponds to a branching fraction B(B^0 -> gamma gamma) = (1.7 +- 1.1(stat.) +- 0.2(syst.)) x 10^-7. Based on this result, we set a 90% confidence level upper limit of B(B^0 -> gamma gamma) < 3.3 x 10^-7.