Search for the rare decays of $D\to h(h^{(')})e^{+}e^{-}$

TL;DR

This study searches for 15 rare $D$ meson decays involving electron-positron pairs, setting new upper limits on their branching fractions with no significant signals observed, thus constraining new physics scenarios.

Contribution

First-time measurement of upper limits on branching fractions for multiple rare $D$ meson decays involving $e^+e^-$ pairs, improving sensitivity by at least a factor of four over previous results.

Findings

No significant signals observed in the decay channels.

Upper limits on branching fractions set at the level of $10^{-6}$ to $10^{-7}$.

First measurements of upper limits for several decay modes.

Abstract

We search for 15 rare decays of $D$ mesons to hadrons accompanied by an electron-positron pair $D\to h(h^{(')})e^{+}e^{-}$, based on 20.3 fb$^{-1}$ of $e^+ e^-$ collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector at BEPCII. No significant signals are observed, and the corresponding upper limits on the branching fractions at the 90\% confidence level are determined. The sensitivities of the results are at the level of $10^{-6}$ $\sim$ $10^{-7}$. The upper limits on the branching fractions for the $D^+\to \rho^{+} e^+ e^-$, $D^+\to K^{*+} e^+ e^-$, $D^0\to K_S^0 K_S^0 e^+ e^-$, $D^0\to \pi^0 \pi^0 e^+ e^-$ and $D^0\to \eta^{\prime} e^+ e^-$ decay channels are measured for the first time. For the $D^0\to \pi^0 e^+ e^-$, $D^0\to \eta e^+ e^-$, $D^0\to \omega e^+ e^-$, $D^0\to K_S^0 e^+ e^-$, $D^+\to \pi^+ \pi^0 e^+ e^-$, $D^+\to K^+ \pi^0 e^+ e^-$, $D^+\to \pi^+ K_S^0 e^+ e^-$ and $D^+\to K^+ K_S^0 e^+ e^-$ decay channels, the upper limits on the branching fractions are determined, with an improvement of at least a factor of four compared to previous searches. The upper limits on the branching fractions for the $D^0\to \rho^{0} e^+ e^-$ and $D^0\to \phi e^+ e^-$ decay channels are set at $0.7 \times 10^{-6}$ and $4.6 \times 10^{-6}$, respectively.