Further evidence for the $\Sigma^{*}$ resonance with $J^P=1/2^-$ around 1380 MeV

TL;DR

This study provides evidence for a new $ ext{Σ}^*$ resonance with $J^P=1/2^-$ near 1380 MeV, supporting unquenched quark model predictions and analyzing $K^-$ reactions with experimental data.

Contribution

It offers the first strong evidence for the $ ext{Σ}^*$ with $J^P=1/2^-$ around 1380 MeV using effective Lagrangian analysis of $K^-$ reactions.

Findings

Evidence for $ ext{Σ}^*$ with $J^P=1/2^-$ around 1380 MeV

Comparison of theoretical predictions with experimental data

Necessity for higher statistics data

Abstract

The unquenched quark models predict the new particle $\Sigma^*$ with spin parity $J^P=1/2^-$ and its mass is around the well established $\Sigma^*(1385)$ with $J^P=3/2^+$. Here by using the effective Lagrangian approach we study \kp\ reaction at the range of $\Lambda^{*}(1520)$ peak, comparing the resulting total cross section, and $\pi^+\pi^-$, $\Lambda\pi^+$, $\Lambda\pi^-$ invariant squared mass distributions for various incident $K^-$ momenta, as well as the production angular distribution of the $\Lambda$ with the data from the Lawrence Berkeley Laboratory 25-inch hydrogen bubble chamber, we find that, apart from the existing resonance $\Sigma^{*}(1385)$ with $J^P=3/2^+$, there is a strong evidence for the existence of the new resonance $\Sigma^{*}$ with $J^P=1/2^-$ around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.