Σ- production spectrum in the inclusive (π-, K+) reaction on 209Bi and the Σ-nucleus potential

We investigate theoretically the Sigma(-) hypernuclear production by the inclusive (pi(-), K+) reaction on a neutron-excess Bi-209 target in the framework of a distorted wave impulse approximation with an optimal Fermi-averaging for the elementary pi(-) + p -> K+ + Sigma(-) t-matrix. In order to study the Sigma-nucleus potentials constructed with isoscalar and isovector components, we compare the calculated spectra of the Bi-209(pi(-), K+) reaction with the experimental data at KEK, using several Sigma-nucleus (optical) potentials for Sigma(-)-Pb-208 which are determined by fits to the Sigma(-) atomic X-ray data. Our analysis confirms that the potentials having a repulsion inside the nuclear surface and an attraction outside the nucleus with a sizable absorption, can well reproduce the data. But it is still difficult to discriminate among the radial distributions of these potentials inside the heavy nucleus. The contribution of the isovector component in the potential is not determined uniquely by the Bi-209(pi(-), K+) spectrum. (c) 2006 Elsevier B.V. All rights reserved.