Repulsion and absorption of the Σ -nucleus potential for Σ - He 5 in the Li 6 (π-,K+) reaction

We study phenomenologically inclusive spectra of the Li6(π-,K+) reaction at 1.2 GeV/c within a distorted-wave impulse approximation with the optimal Fermi-averaging π-p→K+Σ-t matrix. We attempt to clarify the property of a Σ-nucleus potential for Σ - He5 by comparing the calculated spectra with the data of the J-PARC E10 experiment. The result shows that the repulsive and absorptive components of the Σ - He5 potential provide the ability to explain the data of the continuum spectra in Σ and Λ regions; the strengths of VΣ=+30±10 MeV and WΣ=-26±2 MeV are favored within the Woods-Saxon potential, consistent with analyses for heavier nuclei. Effects of the size and potential range for Σ - He5 in the neutron excess of (N-Z)/(N+Z)= 0.2 are also discussed.