Interaction of $η$ mesons with a three-nucleon system

Abstract

A study of the $η$-3N interaction in the energy region near the $η$-^3H elastic scattering threshold is presented. The calculational scheme is based on the four-body scattering formalism. A manageable form of the integral equations is achieved by using a separable ansatz for the driving two-body $ηN$- and NN-forces as well as for the subamplitudes appearing in the (1+3) and (2+2) partitions of the $η$-3N system. Results presented for the $η$-^3H scattering length point to the existence of a virtual (antibound) s-wave $η$-^3H state. As a consequence, a large enhancement of the cross section for $η$-production from three-body nuclei is predicted.