Photo-excitation of hyperons and exotic baryon in gamma N --> K Anti-K N

Abstract

We investigate the reaction of $\gamma N\to K\bar{K}N$ focusing on the photoproduction of $\Lambda (1520)$ and putative exotic $\Theta (1540)$. We consider various background production mechanisms including the production of vector mesons, tensor mesons, and other $\Lambda$ and $\Sigma$ hyperons. We discuss the angular distribution of $\Lambda (1520)$ photoproduction cross section and the radiative decays of $\Lambda (1520)$. We also discuss what we expect for the invariant mass distributions if the $\Theta (1540)$ is formed in the reaction, with the parameters studied so far. We find that the peak in the $KN$ invariant mass distribution, if confirmed, can hardly come from the kinematic reflections, especially, due to the tensor meson backgrounds.

Comments: 4 pages, 2 figures, presented at Workshop on the Physics of Excited Nucleons (NSTAR 2005), Tallahassee, Florida, 12-15 Oct 2005