Width of the $\Delta$ resonance in nuclei

Abstract

In this work we evaluate the imaginary part of the isobar $\Delta$ self-energy ${\Sigma }_{\Delta }$ from the two-body absorption process $\Delta +N\to 2N$. This contribution is calculated using a recently developed non-relativistic scheme, which allows for an evaluation of the self-energy with a basis of single-particle states appropriate for both bound hole states and for particle states in the continuum. In order to test the medium dependence of the self-energy, we calculate the two-body absorption term ${\Sigma }_{\Delta }^{A2}$ for several finite nuclei with $N=Z$, i.e.\ ${}^{16}$O, ${}^{40}$Ca and ${}^{100}$Sn. The resulting self-energy, which is energy dependent and non-local, is compared with a simple parameterization derived from nuclear matter.

Comments: 5 pages 3 figures can be obtained from the authors, TU-93-1609