Nuclear contacts of unstable nuclei

TL;DR

This paper theoretically investigates nuclear short-range correlations in unstable nuclei near $^{132}$Sn, revealing suppression patterns and universal behaviors of nuclear contacts, which are crucial for understanding nuclear structure and correlations.

Contribution

It provides the first theoretical analysis of nuclear contacts in unstable nuclei, highlighting suppression effects and universal relations in SRCs near doubly magic nuclei.

Findings

Proton-proton contact decreases with excess neutrons in Sn isotopes.

A linear relation exists between proton-proton contact and proton number in N=82 isotones.

Suppression of SRCs resembles suppression of $ ext{α}$-clustering in the same isotopic chain.

Abstract

Nuclear contact is a key quantity to describe the nucleon-nucleon short-range correlations (SRCs). While they have been determined by electron scattering experiments for selected stable nuclei, nuclear contacts are largely unknown for unstable nuclei. In this work, we study nuclear contacts for a number of nuclei in the vicinity of the doubly magic $^{132}$Sn from the theoretical perspective, with special emphasis on unstable nuclei. We find that the proton-proton contact generally gets suppressed by the excess neutrons for the Sn isotopes, resembling the suppression of $\alpha$-cluster formation reported recently for the same isotopic chain [J. Tanaka $\textit{et al}.$, Science $\textbf{371}$, 260 (2021)]. This indicates a hidden universal aspect of SRCs and $\alpha$ clustering, two different kinds of nuclear correlations. Meanwhile, a linear relation is found between the proton-proton contact and the proton number for the $N=82$ isotones. Our results can be helpful for future experimental studies of SRCs in unstable nuclei at advanced facilities worldwide.