Combined analysis of the $γn \to K^0Σ^0$ and $γn \to K^+Σ^-$ reactions

Abstract

The recently released data on differential cross sections for $γn \to K^0Σ^0$ from the A2 and BGOOD Collaborations are used to examine the theoretical model constructed in our previous work [Phys. Rev. D \textbf{105}, 094017 (2022)] for $γn \to K^+Σ^-$, and it is found that the model predictions are able to qualitatively reproduce the A2 data but fail to describe the BGOOD data. Then, a combined analysis of the $γn \to K^0Σ^0$ and $γn \to K^+Σ^-$ reactions is performed to revise the theoretical model. Due to the inconsistency problem, the A2 and BGOOD data are included in fits separately. In the case of including the A2 data, both the data for $γn \to K^0Σ^0$ and $γn \to K^+Σ^-$ can be fairly well described, and the contributions from the $N(1710)1/2^+$, $N(1880)1/2^+$, $N(1900)3/2^+$, and $Δ(1920)3/2^+$ resonances are found to dominate the reactions in the lower energy region. While in the case of including the BGOOD data, although most of the data for the $γn \to K^+ Σ^-$ reaction can be described with the exception of some noticeable discrepancies on beam asymmetries at lower energies, the BGOOD data for $γn \to K^0Σ^0$ can be only qualitatively described, and the contributions from the $N(1710)1/2^+$, $N(1900)3/2^+$, and $Δ(1910)1/2^+$ resonances are found to dominate the reactions in the lower energy region. In both cases, the $t$-channel $K^\ast(892)$ exchange is found to play a crucial role at forward angles in the higher energy region. Further precise measurements of data for $γn \to K^0Σ^0$ are called on to disentangle the discrepancies between the data sets from the A2 and BGOOD Collaborations.