Three-body Effect in Short-range Correlations

TL;DR

This paper presents an  initio method to calculate two-nucleon densities including three-body effects, providing insights into short-range correlations in nuclei and extending predictions to unstable isotopes.

Contribution

It introduces the explicit inclusion of three-body density operators in  initio calculations, improving the understanding of short-range correlations in nuclei.

Findings

Pronounced three-body effects in O two-nucleon densities.

Benchmarking shows good agreement with no-core shell model results.

Extension of calculations to oxygen isotopic chain with predictions for SRC measurements.

Abstract

Short-range correlations (SRCs) provide the link between low- and high-energy nuclear physics and can be quantified by two-nucleon densities. We present calculations of the two-nucleon densities using free-space similarity renormalization group (SRG)-evolved operators and in-medium SRG (IMSRG) ground states with softend chiral interaction. Our calculations benchmark well against no-core shell model (NCSM) results with unevolved oparetors and Hamiltonians in $^4\mathrm{He}$. We explicitly include the induced three-body (3b) density operators for the first time which, together with the 3b Hamiltonians, provide the full 3b effects. We show pronounced 3b effects in the $^{16}\mathrm{O}$ two-nucleon densities. Combined with valence-space IMSRG (VS-IMSRG) method, we extend the calculation to the oxygen isotopic chain. This approach enables a consistent \textit{ab initio} description of low-energy properties and SRCs within one framework and offers predictions for the upcoming SRC measurements in unstable nuclei.