Quantum Monte Carlo Calculations with Chiral Effective Field Theory Interactions

Abstract

We present the first quantum Monte Carlo (QMC) calculations with chiral effective field theory (EFT) interactions. To achieve this, we remove all sources of nonlocality, which hamper the inclusion in QMC calculations, in nuclear forces to next-to-next-to-leading order. We perform auxiliary-field diffusion Monte Carlo (AFDMC) calculations for the neutron matter energy up to saturation density based on local leading-order, next-to-leading order, and next-to-next-to-leading order nucleon-nucleon interactions. Our results exhibit a systematic order-by-order convergence in chiral EFT and provide nonperturbative benchmarks with theoretical uncertainties. For the softer interactions, perturbative calculations are in excellent agreement with the AFDMC results. This work paves the way for QMC calculations with systematic chiral EFT interactions for nuclei and nuclear matter, for testing the perturbativeness of different orders, and allows for matching to lattice QCD results by varying the pion mass.

Functional renormalization group studies of nuclear and neutron matter

“…Different approaches, such as chiral effective field theory (ChEFT [12,90,91]), chiral Fermi liquid theory [98], as well as Quantum Monte Carlo (QMC) methods using either phenomenological interactions [99,100] or ChEFT potentials [101,102,103], show satisfactory agreement in their common overlap regions of applicability at lower densities.…”

Minimally nonlocal nucleon-nucleon potentials with chiral two-pion exchange includingΔresonances

“…(2.6) generate contributions at NLO and N3LO-such a choice nevertheless leads to smooth functions for the potential components v l S (r) and the resulting deuteron waves. Sharper cutoffs, like those ∝ exp [−(r/R) n ] with n = 4, as suggested in Ref [53], or n = 6, as in one of the earlier versions of the present model, generate wiggles in the deuteron waves at r ∼ R (as well as mixing of power-counting orders).…”

Spin-polarized neutron-rich matter at different orders of chiral effective field theory

“…Estimates of theoretical uncertainties [32] for calculations of the equation of state of nuclear and neutron matter have largely focused on varying the low-energy constants and resolution scale at which nuclear dynamics are probed [33][34][35][36][37][38]. In a recent work [40], we layed the foundations for order-by-order calculations of nuclear many-body systems by presenting consistent NLO and N 2 LO chiral nuclear forces whose relevant short-range three-nucleon forces (3NF) are fit to A = 3 binding energies and the lifetime of the triton [39].…”