Search for $D^0 \to \ell^+\ell^-$ and $D^0 \to \gamma\gamma$ at BaBar and BESIII

TL;DR

This paper reports on searches for rare $D^0$ meson decays into lepton pairs and photon pairs conducted by BaBar and BESIII, finding no evidence of such decays, consistent with Standard Model expectations.

Contribution

It presents the first combined search results for $D^0 o ext{lepton pairs}$ and $D^0 o ext{photon pairs}$, including new preliminary results from BESIII.

Findings

No significant signals observed for the decays.

Results are consistent with Standard Model predictions.

Upper limits set on branching fractions.

Abstract

Three searches for rare decays of the charmed $D^0$ meson are presented: a search for $D^0 \to \ell^+\ell^-$ published by the BaBar collaboration using about 468 fb$^{-1}$ of data and two searches for $D^0 \to \gamma\gamma$, one published by the BaBar collaboration using about 470 fb$^{-1}$ of data, and a second one presented as a preliminary result by the BESIII collaboration using approximately 2.9 fb$^{-1}$. No statistically significant signal has been found, in agreement with the Standard Model predictions.