Evolving Nuclear Many-Body Forces with the Similarity Renormalization Group

TL;DR

This paper discusses advances in the Similarity Renormalization Group method for nuclear physics, enabling consistent evolution of many-body forces and improving calculations for p-shell nuclei with preserved force hierarchies.

Contribution

It extends the SRG approach to p-shell nuclei, demonstrating the hierarchy of many-body forces and improved convergence in nuclear calculations.

Findings

Consistent evolution of Hamiltonians in three-particle space.

Moderate contributions from induced four-body forces.

Improved convergence properties in p-shell nuclei.

Abstract

In recent years, the Similarity Renormalization Group has provided a powerful and versatile means to soften interactions for ab initio nuclear calculations. The substantial contribution of both induced and initial three-body forces to the nuclear interaction has required the consistent evolution of free-space Hamiltonians in the three-particle space. We present the most recent progress on this work, extending the calculational capability to the p-shell nuclei and showing that the hierarchy of induced many-body forces is consistent with previous estimates. Calculations over a range of the flow parameter for 6Li, including fully evolved NN+3N interactions, show moderate contributions due to induced four-body forces and display the same improved convergence properties as in lighter nuclei. A systematic analysis provides further evidence that the hierarchy of many-body forces is preserved.