Amplitude analysis and branching fraction measurement of $J/\psi \to \Lambda\bar{\Sigma}^0\eta +\mathrm{c.c}$

TL;DR

This paper presents the first partial-wave analysis of the decay $J/ o ext{Lambda Sigma Eta}$ using a large $J/ o$ sample, identifying dominant excited Lambda states and measuring their properties and the decay's branching fraction.

Contribution

First-time partial-wave analysis of $J/ o ext{Lambda Sigma Eta}$ decay, identifying key excited Lambda states and measuring their masses, widths, and branching fraction.

Findings

Dominant contributions from excited $ ext{Lambda}$ states with $J^P=1/2^-$ and $J^P=1/2^+$.

Measured masses and widths of $ ext{Lambda}(1670)$ and $ ext{Lambda}(1810)$.

Branching fraction of $J/ o ext{Lambda Sigma Eta}$ decay is $(3.44 imes 10^{-5})$.

Abstract

Based on a sample of $(10087\pm44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector, a partial-wave analysis of $ J/\psi \to \Lambda \bar{ \Sigma }^0\eta +\mathrm{c.c} $ is performed for the first time. The dominant contributions are found to be excited $\Lambda$ states with $J^P=1/2^-$ and $J^P=1/2^+$ in the $\eta\Lambda$ mass spectra. The measured masses and widths are $M=1668.8\pm3.1\pm21.2$ MeV/$c^2$ and $\Gamma=52.7\pm4.2\pm17.8$ MeV for the $\Lambda(1670)$, and $M=1881.5\pm16.5\pm20.3$ MeV/$c^2$ and $\Gamma=82.4\pm18.2\pm8.9$ MeV for the $\Lambda(1810)$, respectively. The branching fraction is determined to be $ \mathcal{B}(J/\psi \to \Lambda \bar{ \Sigma }^0\eta +\mathrm{c.c}) $ = $(3.44 \pm 0.11 \pm 0.13) \times 10^{-5}$. The first uncertainties are statistical and the second systematic.