Is the Σ–nucleus potential for image atoms consistent with the image data? Original Research Article

In order to examine whether the Σ–nucleus potential for Σ− atoms can explain the experimental (π−,K+) data or not, we evaluate Σ− hypernuclear production by the (π−,K+) reaction on a 28Si target, in the framework of a distorted-wave impulse approximation with an optimal Fermi-averaging for the elementary π−+p→K++Σ− t-matrix. Inclusive K+ spectra of the View the MathML source reaction are calculated with several Σ–nucleus (optical) potentials for View the MathML source which are determined by fits to the Σ− atomic X-ray data, and the properties of these potentials are tested in detail by comparing the calculated spectra with the (π−,K+) experimental data at KEK. The results show that the potentials having a repulsion inside the nuclear surface and an attraction outside the nucleus with a sizable absorption, can reproduce the View the MathML source data very well; the optimal Fermi-averaging for the π−+p→K++Σ− reaction also gives a good description of the energy-dependence in the Σ− quasi-free spectrum. This is the first successful attempt to explain simultaneously the Σ− atomic X-ray data and the (π−,K+) reaction.