Regulator Artifacts in Uniform Matter for Chiral Interactions

TL;DR

This paper investigates how different regulator functions in chiral nuclear interactions influence artifacts and physical predictions in uniform matter calculations, highlighting the importance of regulator choice.

Contribution

It characterizes the effects of various cutoff regulators on nuclear matter properties and tests the normal-ordering approximation for three-nucleon forces.

Findings

Regulator choice significantly affects artifacts in nuclear matter calculations.

Different regulators influence the size of residual three-nucleon contributions.

Uniform matter provides a clear testbed for analyzing regulator effects.

Abstract

Regulator functions applied to two- and three-nucleon forces are a necessary ingredient in many-body calculations based on chiral effective field theory interactions. These interactions have been developed recently with a variety of different cutoff forms, including regulating both the momentum transfer (local) and the relative momentum (nonlocal). While in principle any regulator that suppresses high momentum modes can be employed, in practice artifacts are inevitable in current power counting schemes. Artifacts from particular regulators may cause significant distortions of the physics or may affect many-body convergence rates, so understanding their nature is important. Here we characterize the differences between cutoff effects using uniform matter at Hartree-Fock and second-order in the interaction as a testbed. This provides a clean laboratory to isolate phase-space effects of various regulators on both two- and three-nucleon interactions. We test the normal-ordering approximation for three-nucleon forces in nuclear matter and find that the relative size of the residual 3N contributions is sensitive to the employed regularization scheme.