Clustering structure of nuclei in deep inelastic processes

TL;DR

This paper investigates the clustering structure of the $^9$Be nucleus in deep inelastic scattering, analyzing nuclear modifications of the structure function $F_2$ and exploring how clustering influences these modifications.

Contribution

It provides a comparison between clustering effects in nuclear structure functions using AMD and shell models, suggesting clustering impacts are small in the conventional part.

Findings

Clustering effects are small in the conventional structure function.

Large nuclear modification slope may be linked to internal nucleon modifications.

Short-range correlations are influenced by high-density cluster formations.

Abstract

A clustering aspect is explained for the $^9$Be nucleus in charged-lepton deep inelastic scattering. Nuclear modifications of the structure function $F_2$ are studied by the ratio $R_{\rm EMC} = F_2^A /F_2^D$, where $A$ and $D$ are a nucleus and the deuteron, respectively. In a JLab experiment, an unexpectedly large nuclear modification slope $|dR_{\rm EMC}/dx|$ was found for $^9$Be, which could be related to its clustering structure. We investigated a mean conventional part of a nuclear structure function $F_2^A$ by a convolution description with nucleon momentum distributions calculated by antisymmetrized (or fermionic) molecular dynamics (AMD) and also by a simple shell model. We found that clustering effects are small in the conventional part, so that the JLab result could be associated with an internal nucleon modification or a short-range nuclear correlation which is caused by high densities due to cluster formation.