Nuclear sigma term in the Skyrme model: Pion-nucleus interaction

Abstract

The nuclear sigma term is calculated including the nuclear matrix element of the derivative of the $\mathrm{NN}$ interaction with respect to the quark mass, ${m}_{q}\ensuremath{\partial}{V}_{\mathrm{NN}}/\ensuremath{\partial}{m}_{q}.$ The $\mathrm{NN}$ potential is evaluated in the Skyrmion-Skyrmion picture within the quantized product ansatz. The contribution of the $\mathrm{NN}$ potential to the nuclear sigma term provides repulsion to the pion-nucleus interaction. The strength of the $s$-wave pion-nucleus optical potential is estimated including such a contribution. The results are consistent with the analysis of the experimental data.