Charm Decays and Spectroscopy at BABAR

TL;DR

This paper reports on searches for rare charm decays and flavor-changing neutral-current processes using large datasets from the BABAR experiment, setting new limits on their branching fractions to probe potential new physics.

Contribution

It presents the first search results and improved limits for rare charm decays and neutral-current processes using extensive BABAR data, enhancing constraints on new physics models.

Findings

No evidence for the rare decays was observed.

New upper limits on branching fractions were established.

Results provide tighter constraints on new physics contributions.

Abstract

We present searches for rare charm decays of the form $X_c^+ \to h^{\pm} \ell^{\mp} \ell^{(')^+}$, where $X_c^+$ is a charm hadron either $D^+$, $D_s^+$, or $\Lambda_c^+$, and $\ell^{(')^{\pm}}$ is an electron or muon. These modes are based on 384 $fb^{-1}$ of $e^+ e^-$ annihilation data collected at the $\Upsilon(4S)$ resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We also present the flavor-changing neutral-current decays $D^0 \to e^+e^-$, $D^0 \to \mu^+ \mu^-$, and $D^0 \to e^{\pm} \mu^{\mp}$ that corresponds to an integrated luminosity of 468 $fb^{-1}$ of data. The decay $D^0 \to e^+ \mu^-$ is further lepton-flavor violating, and thus occur only through very slow neutrino mixing. These decays constitute sensitive probes for possible new-physics contribution. We report new limits on the branching fractions of these decays.