Neutron matter from local chiral effective field theory interactions at large cutoffs

Neutron matter is an important many-body system that provides valuable constraints for the equation of state (EOS) of neutron stars. Neutron-matter calculations employing chiral effective field theory (EFT) interactions have been extensively used for this purpose. Among the various many-body methods, quantum Monte Carlo (QMC) methods stand out due to their nonperturbative nature and the achievable precision. However, QMC methods require local interactions as input, which leads to the appearance of stronger regulator artifacts compared to nonlocal interactions. To circumvent this, we employ large-cutoff interactions derived within chiral EFT (400 MeV ≤ Λ_𝑐 ≤ 700MeV) for studies of pure neutron matter. These interactions have been adjusted to nucleon-nucleon scattering phase shifts, the triton binding energy, as well as the triton 𝛽-decay half-life. We find that regulator artifacts significantly decrease with increasing cutoff, leading to a significant reduction of uncertainties in the neutron-matter EOS. We discuss implications for the symmetry energy and demonstrate how our new calculations lead to a reduction in the theoretical uncertainty of predicted neutron-star radii by up to 30% for low-mass stars.. Authors: Tews, Ingo [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000326566355); Somasundaram, Rahul [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Syracuse University, NY (United States)] (ORCID:0000000304273893); Lonardoni, Diego [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000169568989); Göttling, Hannah [Technische Universität Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany)] (ORCID:0009000574545956); Seutin, Rodric [Technische Universität Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Max-Planck-Institut für Kernphysik, Heidelberg (Germany)]. DOE Contract: AC02-05CH11231; AC52-06NA25396. Subjects: 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Ab initio calculations; Diffusion quantum Monte Carlo; Equations of state of nuclear matter; Monte Carlo methods; Nuclear astrophysics; Nuclear forces; Nuclear many-body theory; Nuclear matter; Nuclear matter in neutron stars; Quantum Monte Carlo