Study of the decays $\chi_{cJ} \rightarrow \Lambda \bar{\Lambda}\phi$

TL;DR

This paper reports the first evidence and observation of specific decay modes of $ ext{chi}_{cJ}$ particles into $ ext{Lambda}ar{ ext{Lambda}} ext{phi}$, measuring their branching fractions with high significance using a large data sample.

Contribution

First evidence and observation of $ ext{chi}_{cJ} o ext{Lambda}ar{ ext{Lambda}} ext{phi}$ decays with measured branching fractions, expanding understanding of charmonium decay channels.

Findings

First evidence of $ ext{chi}_{c0} o ext{Lambda}ar{ ext{Lambda}} ext{phi}$ decay.

First observation of $ ext{chi}_{c1,2} o ext{Lambda}ar{ ext{Lambda}} ext{phi}$ decays.

Measured branching fractions for these decays with statistical and systematic uncertainties.

Abstract

Based on $(2712.4 \pm 14.3) \times 10^{6}$ $ e^{+}e^{-}\to\psi(3686)$ events collected with the BESIII detector operating at the BEPCII collider, we report the first evidence of $\chi_{c0}\to \Lambda\bar \Lambda \phi$ decays and the first observation of $\chi_{c1,2}\to \Lambda\bar \Lambda \phi$ decays, with significances of $4.5\sigma$, $11.3\sigma$ and $13.0\sigma$, respectively. The decay branching fractions of $\chi_{c0,1,2}\to \Lambda\bar \Lambda\phi$ are measured to be $( 2.99\pm1.24\pm0.19) \times 10^{-5}$, $(6.01\pm0.90\pm0.40 )\times 10^{-5}$, and $(7.13\pm0.81\pm0.36) \times 10^{-5}$, where the first uncertainties are statistical and the second systematic. No obvious enhancement near the $\Lambda \bar{\Lambda}$ production threshold or excited $\Lambda$ state is found in the $\Lambda \phi$ (or $\bar{\Lambda}\phi$) system.