Possible $\Sigma({1\over2}^-)$ under the $\Sigma^*(1385)$ peak in $K\Sigma^*$ photoproduction

TL;DR

This paper investigates the $ ightarrow$ reaction in photoproduction, proposing a new $rac{1}{2}^-$ $ ightarrow$ state near 1380 MeV to explain experimental beam asymmetry data, using an effective Lagrangian approach.

Contribution

The study introduces a new $rac{1}{2}^-$ $ ightarrow$ state around 1380 MeV into the theoretical model, improving agreement with experimental data.

Findings

Including the $rac{1}{2}^-$ state reproduces experimental results.

The $rac{1}{2}^-$ state and contact terms are significant in the reaction.

The model suggests further investigation into these contributions.

Abstract

The LEPS collaboration has recently reported a measurement of the reaction $\gamma n\to K^+\Sigma^{*-}(1385)$ with linearly polarized photon beam at resonance region. The observed beam asymmetry is sizably negative at $E_\gamma=1.8-2.4 \mathrm{GeV}$, in contrast to the presented theoretical prediction. In this paper, we calculate this process in the framework of the effective Lagrangian approach. By including a newly proposed $\Sigma(J^P={1\over2}^-)$ state with mass around 1380~MeV, the experimental data for both $\gamma n$ and $\gamma p$ experiments can be well reproduced. It is found that the $\Sigma({1\over2}^-)$ and/or the contact term may play important role and deserve further investigation.