On Quasibound N* Nuclei

TL;DR

This paper explores the theoretical possibility of unstable bound states involving the N*(1535) resonance and nuclei, suggesting potential quasibound states with specific energies and broad widths, influenced by meson exchange interactions.

Contribution

It introduces a simple meson-exchange model to evaluate N*–nucleus potentials, predicting the existence of quasibound states with specific energies and sensitivities to interaction parameters.

Findings

Supports 2-3 bound states in N*–nucleus systems.

Identifies a very weakly bound state in N*–$^3$He at a few keV.

Predicts broad widths (~80-110 MeV) for these quasibound states.

Abstract

The possibility for the existence of unstable bound states of the S11 nucleon resonance N$^*$(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N$^*$ interaction involving a pion and eta meson exchange, N$^*$-nucleus potentials for N*-$^3$He and N*-$^{24}$Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-$^3$He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N$^*$ $\pi$ and N N$^*$ $\eta$ vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with $\Gamma \sim$ 80 and 110 MeV for N*-$^3$He and N*-$^{24}$Mg respectively.