We adopt a novel formalism for the low-energy analysis of the $\gamma p\to K^{+}\pi \mathrm{\Sigma }$ photoproduction reaction, outlined recently in [P. C. Bruns, arXiv:2012.11298.], to calculate the $\pi \mathrm{\Sigma }$ invariant mass distributions in the $\mathrm{\Lambda }(1405)$ 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 $\pi \mathrm{\Sigma }-\overline{K}N$ model amplitudes which should enable one to constrain the parameter space of these models.

• Received 23 June 2022
• Accepted 27 September 2022

DOI:https://doi.org/10.1103/PhysRevD.106.074017