Effective field theory in the harmonic oscillator basis

TL;DR

This paper introduces a new approach to chiral effective field theory interactions tailored for the harmonic oscillator basis, improving convergence in nuclear structure calculations.

Contribution

It develops a method to construct EFT interactions directly in the harmonic oscillator basis, enhancing convergence and computational efficiency in nuclear many-body problems.

Findings

Ultraviolet convergence is built-in by construction.

Infrared convergence achieved by enlarging the model space.

Fast convergence of ground-state energies and radii in nuclei up to 132Sn.

Abstract

We develop interactions from chiral effective field theory (EFT) that are tailored to the harmonic oscillator basis. As a consequence, ultraviolet convergence with respect to the model space is implemented by construction and infrared convergence can be achieved by enlarging the model space for the kinetic energy. In oscillator EFT, matrix elements of EFTs formulated for continuous momenta are evaluated at the discrete momenta that stem from the diagonalization of the kinetic energy in the finite oscillator space. By fitting to realistic phase shifts and deuteron data we construct an effective interaction from chiral EFT at next-to-leading order. Many-body coupled-cluster calculations of nuclei up to 132Sn exhibit a fast convergence of ground-state energies and radii in feasible model spaces.