Analysis of recent CLAS data on $\Sigma ^{\ast }(1385)$ photoproduction off a neutron target

TL;DR

This paper models $ ext{Sigma}(1385)$ photoproduction off a neutron using an effective Lagrangian approach with Regge trajectories, successfully describing experimental data and highlighting the importance of gauge invariance restoration.

Contribution

It introduces a gauge-invariant Regge-based model for $ ext{Sigma}(1385)$ photoproduction that does not explicitly include baryon resonances, providing a good fit to recent CLAS data.

Findings

The model accurately reproduces experimental cross sections.

Gauge-invariance restoration significantly affects the results.

Final-state interactions may be important as indicated by fitted parameters.

Abstract

Based on recent experimental data obtained by the CLAS Collaboration, the $\Sigma(1385)$ photoproduction off a neutron target at laboratory photon energies $E_\gamma$ up to 2.5\,GeV is investigated in an effective Lagrangian approach including $s$-, $u$-, and $t$-channel Born-term contributions. The present calculation does not take into account any explicit $s$-channel baryon-resonance contributions, however, in the spirit of duality, we include $t$-channel exchanges of mesonic Regge trajectories. The onset of the Regge regime is controlled by smoothly interpolating between Feynman-type single-meson exchanges and full-fledged Regge-trajectory exchanges. Gauge invariance broken by the Regge treatment is fully restored by introducing contact-type interaction currents that result from the implementation of \textit{local} gauge invariance in terms of generalized Ward-Takahashi identities. The cross sections for the $\gamma n\to K^+\Sigma^*(1385)^-$ reaction are calculated and compared with experimental results from the CLAS and LEPS collaborations. Despite its simplicity, the present theoretical approach provides a good description of the main features of the data. However, the parameters fitted to the data show that the gauge-invariance-restoring contact term plays a large role which may point to large contributions from final-state interactions.