Momentum distribution of N$^*$ in nuclei

TL;DR

This paper investigates the momentum distribution of the N$^*$ resonance within nuclei, highlighting its potential role in eta-mesic nuclei experiments and suggesting narrower distributions for N$^*$-$^3$He quasibound states compared to neutron-$^3$He.

Contribution

It introduces the concept of N$^*$-$^3$He quasibound states and analyzes their momentum distributions, providing insights for experimental searches and data analysis.

Findings

N$^*$-$^3$He momentum distribution is narrower than neutron-$^3$He in $^4$He.

Results for N$^*$-$^{24}$Mg system are also presented.

The work motivates searches for exotic N$^*$-nucleus quasibound states.

Abstract

Due to its dominance in the low energy eta-nucleon interaction, the S11 N$^*$(1535) resonance enters as an important ingredient in the analyses of experiments aimed at finding evidence for the existence of eta-mesic nuclei. The static properties of the resonance get modified inside the nucleus and its momentum distribution is used in deciding these properties as well as the kinematics in the analyses. Here we show that given the possibility for the existence of an N$^*$-$^3$He quasibound state, the relative momentum distribution of an N$^*$ and $^3$He inside such a $^4$He is narrower than that of neutron-$^3$He in $^4$He. Results for the N$^*$-$^{24}$Mg system are also presented. The present exploratory work could be useful in motivating searches of exotic N$^*$-nucleus quasibound states as well as in performing analyses of eta meson production data.