Nucleon and $Δ$ resonances in $γn \to K^+Σ^-$ photoproduction

The most recent data on beam asymmetries, $Σ$, and beam-target asymmetries, $E$, from the CLAS Collaboration, together with the previous data on differential cross sections and beam asymmetries from the CLAS and LEPS Collaborations, for the $γn \to K^+Σ^-$ reaction are studied based on an effective Lagrangian approach in the tree-level Born approximation. The $t$-channel $K$ and $K^\ast(892)$ exchanges, the $u$-channel $Σ$ exchange, the interaction current, and the exchanges of $N$, $Δ$, and their excited states in the $s$ channel are considered in constructing the reaction amplitudes to describe the available experimental data. The reaction mechanisms of $γn \to K^+Σ^-$ are analyzed, and the associated resonances' parameters are extracted. The numerical results show that the $Δ$ exchange and the $N(1710)1/2^+$, $N(1880)1/2^+$, $N(1900)3/2^+$, and $Δ(1920)3/2^+$ resonance exchanges in the $s$-channel dominate the $γn \to K^+Σ^-$ reaction in the lower energy region, and the $t$-channel $K^\ast(892)$ exchange plays a crucial role at forward angles in the higher energy region.

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