Constraining the chirally motivated $\pi \Sigma$-$\bar{K}N$ models with the $\pi \Sigma$ photoproduction mass spectra

Abstract

The paper presents a first time attempt on a combined fit of the $K^{-}p$ low-energy data and the $\pi \Sigma$ photoproduction mass spectra, performed without fixing the meson-baryon rescattering amplitudes to a specific $\pi \Sigma -\bar{K}N$ coupled channels model obtained from fitting exclusively the $K^{-}p$ data. The formalism adopted to describe the photoproduction process is based on chiral perturbation theory and employs a limited number of free parameters. The achieved description of the photoproduction mass distributions is not quite satisfactory, leaving a room for improving the photo-kernel construction, but still provides additional constraints on the positions of the $\Lambda (1405)$ poles. In particular, the presented models tend to limit the mass of the lower pole and yield a larger width of the $\bar{K}N$ related pole at a higher mass.

Comments: 20 pages, 6 figures