Effective Masses and Sizes of N(939), $\Delta \text{mbox}\text{boldmath}(1232)$ and N(1440) in Nuclear Medium

Abstract

The effective masses and sizes of N(939), $\Delta (1232)$ and N(1440) in nuclear medium are calculated for a model in which quarks are subjected to a confinement force quenched by the scalar part of nuclear interactions. At the nuclear matter density, the nucleon swells by 50\% relative to the free nucleon. The masses of $\Delta (1232)$ and N(1440) decrease in nuclear medium more than the nucleon, so that the pion requires less energy to excite them in nuclear medium than it does for a free nucleon.

Comments: 9 pages (2 figures not included, hard copy available upon request), SUT-AS-930801