Repulsion and absorption of the $\Sigma$-nucleus potential for ${\Sigma }^{-}$-${}^5$He in the ${}^6$Li(${\pi }^{-}$, $K^{+}$) reaction

Abstract

We study phenomenologically inclusive spectra of the ${}^6$Li(${\pi }^{-}$, $K^{+}$) reaction at 1.2 GeV/$c$ within a distorted-wave impulse approximation with the optimal Fermi-averaging ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ $t$ matrix. We attempt to clarify the property of a $\Sigma$-nucleus potential for ${\Sigma }^{-}$-${}^5$He 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 ${\Sigma }^{-}$-${}^5$He potential provide the ability to explain the data of the continuum spectra in $\Sigma$ and $\Lambda$ regions; the strengths of $V_{\Sigma }\simeq$ +30 MeV and $W_{\Sigma }\simeq$ $-$26 MeV are favored within the Woods-Saxon potential, consistent with analyses for heavier nuclei. Effects of the size and potential range for ${\Sigma }^{-}$-${}^5$He in the neutron excess of $(N-Z)/(N+Z)=$ 0.2 are also discussed.

Comments: 35 pages, 11 figures