Testing chiral unitary models for the Λ(1405) in K+ πΣ photoproduction

We adopt a novel formalism for the low-energy analysis of the gamma p -> K+ pi Sigma photoproduction reaction, outlined recently in [P. C. Bruns, arXiv:2012.11298.], to calculate the pi Sigma invariant mass distributions in the Lambda(1405) resonance region. The approach adheres to constraints arising from unitarity, gauge invariance, and chiral perturbation theory, and is used without adjusting any model parameters. It is found that the meson-baryon rescattering in the final state has a major impact on the magnitude and structure of the generated spectra that are compared with the experimental data from the CLAS Collaboration. We demonstrate a large sensitivity of the theoretical predictions to the choice of the coupled-channel pi Sigma - (K) over barN model amplitudes which should enable one to constrain the parameter space of these models.

Automated summary

This study adopts a novel formalism to analyze the low-energy gamma p -> K+ pi Sigma photoproduction reaction. The meson-baryon rescattering is found to have a significant impact on the generated spectra, and is compared with experimental data.