Analysis of the $\gamma n \to K^+ \Sigma^-(1385)$ photoproduction

TL;DR

This study extends a previously developed effective Lagrangian model to analyze the photoproduction of $ ext{K}^+ ext{Σ}^-(1385)$ on neutrons, identifying the dominant resonance and clarifying reaction mechanisms through comparison with experimental data.

Contribution

It demonstrates that the $ ext{Δ}(1930){5/2}^-$ resonance is essential for describing $ ext{K}^+ ext{Σ}^-(1385)$ photoproduction data, advancing understanding of reaction mechanisms.

Findings

The $ ext{Δ}(1930){5/2}^-$ resonance is crucial for reproducing data.

Background contributions are dominated by generalized contact term and $t$-channel $K$ exchange.

The resonance explains the bump in total cross sections.

Abstract

In our previous work [Phys. Rev. D $\bf{101}$, 074025 (2020)], the photoproduction $\gamma p \to K^+ \Sigma^0(1385)$ has been investigated within an effective Lagrangian approach. There, the reaction amplitudes were constructed by considering the $t$-channel $K$ and $K^\ast(892)$ exchanges, $s$-channel $N$ contribution, $u$-channel $\Lambda$ exchange, generalized contact term, and a minimum number of $s$-channel $N$ and $\Delta$ resonance diagrams. It was found that the inclusion of one of the $N(1895){1/2}^-$, $\Delta(1900){1/2}^-$, and $\Delta(1930){5/2}^-$ resonances is essential to reproduce the available differential and total cross-section data for $\gamma p \to K^+ \Sigma^0(1385)$. In the present work, we employ the same model to study the photoproduction $\gamma n \to K^+ \Sigma^-(1385)$, with the purpose being to understand the reaction mechanism and, in particular, to figure out which one of the $N(1895){1/2}^-$, $\Delta(1900){1/2}^-$, and $\Delta(1930){5/2}^-$ resonances is really capable for a simultaneous description of the data for both $K^+ \Sigma^0(1385)$ and $K^+ \Sigma^-(1385)$ photoproduction reactions. The results show that the available data on differential and total cross sections and photo-beam asymmetries for $\gamma n \to K^+ \Sigma^-(1385)$ can be reproduced only with the inclusion of the $\Delta(1930){5/2}^-$ resonance rather than the other two. The generalized contact term and the $t$-channel $K$ exchange are found to dominate the background contributions. The resonance $\Delta(1930){5/2}^-$ provides the most important contributions in the whole energy region considered, and it is responsible for the bump structure exhibited in the total cross sections.