On Gamov states of Sigma^+ hyperons

Both the FINUDA and AMADEUS experiments evidenced a low $\Sigma^+$ momentum component when investigating $\Sigma^+ \pi^-$ pairs produced in K$^-$ nuclear capture. This component is interpreted as a consequence of Gamov state formation, with the hyperon trapped in the Coulomb field of the residual nucleus. Description of such states and their participation in the capture reaction is presented. Some consequences are indicated.