In-Medium Similarity Renormalization Group for Open-Shell Nuclei

TL;DR

This paper develops a nonperturbative IM-SRG method to derive effective Hamiltonians for open-shell nuclei, successfully applying it to lithium-6 and oxygen-18, achieving accurate spectra and advancing shell model techniques.

Contribution

It introduces a nonperturbative IM-SRG approach for open-shell nuclei and demonstrates its effectiveness in calculating nuclear spectra beyond traditional methods.

Findings

Accurately reproduces lithium-6 spectrum in agreement with ab-initio results.

Provides a systematic shell model approach for oxygen-18 beyond diagrammatic methods.

Demonstrates the potential of IM-SRG for complex nuclear structure calculations.

Abstract

We present a nonperturbative derivation of effective valence-shell Hamiltonians in the framework of the recently developed in-medium similarity renormalization group (IM-SRG). As a first application, we calculate the spectra of $p$- and $sd$-shell nuclei, $^6$Li and $^{18}$O, based on evolved chiral nucleon-nucleon interactions. For $^6$Li, the spectrum is in very good agreement with ab-initio results. For $^{18}$O, the IM-SRG provides a new method for the shell model to systematically go beyond effective interaction techniques based on diagrammatic expansions.