Search for a bound state of $\Lambda_{c}\bar{\Sigma}_{c}$ near threshold

TL;DR

This study searches for a hypothesized $ ext{Lambda}_c ar{ ext{Sigma}}_c$ bound state near threshold using electron-positron collision data, but finds no significant evidence and sets upper limits on production cross sections.

Contribution

First experimental search for a $ ext{Lambda}_c ar{ ext{Sigma}}_c$ bound state in $e^{+}e^{-}$ collisions, establishing upper limits on its production cross section.

Findings

No significant signal observed.

Upper limits on cross section range from 1.1 pb to 6.4 pb.

Constraints on possible bound state properties.

Abstract

We search for a possible $\Lambda_{c} \bar{{\Sigma}}_{c}$ bound state, denoted as $H_{c}^{\pm}$, via the $ e^{+}e^{-} \to \pi^{+} \pi^{-} \Lambda_{c}^{+}\bar{\Lambda}_{c}^{-}$ process for the first time. This analysis utilizes 207.8 and 159.3 pb$^{-1}$ of $e^{+}e^{-}$ annihilation data at the center-of-mass energies of 4918.02 and 4950.93 MeV, respectively, collected with the BESIII detector at the BEPCII collider. No statistically significant signal is observed. The upper limits of the product of Born cross section and branching fraction $\sigma(e^{+}e^{-} \to \pi^{+} H_c^{-} + c.c.) \times \mathcal{B}(H_c^{-} \rightarrow \pi^{-}\Lambda_{c}^{+}\bar{\Lambda}_{c}^{-})$ at a 90\% confidence level are reported at each energy point and for various $H_{c}$ mass hypotheses (4715, 4720, 4725, 4730, and 4735 MeV/$c^{2}$) and widths (5, 10, or 20 MeV), with the upper limits ranging from 1.1 pb to 6.4 pb.