2025/03/31 by Wang, Teng, Feng, Xu, Lu, Bing-Nan
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2503.23840
We present an ab initio calculation of nuclear β-decay within the framework of nuclear lattice effective field theory (NLEFT), employing auxiliary-field quantum Monte Carlo methods to solve the nuclear many-body problem. Our approach combines next-to-next-to-leading order (NNLO) two- and three-body chiral interactions with one- and two-body axial current operators, all consistently derived in chiral effective field theory. Low-energy constants are determined exclusively from nucleon-nucleon scattering phase shifts and few-body observables for systems with A ≤ 3. Using these interactions and transition operators, we perform two-channel Monte Carlo simulations to compute the β-decay matrix element for 6He, obtaining results in reasonable agreement with experimental measurements. To address the Monte Carlo sign problem, we implement a perturbative expansion around a leading-order Hamiltonian with approximate Wigner-SU(4) symmetry. This systematic approach provides a foundation for extending NLEFT simulations to precision studies of weak processes in medium-mass nuclei.