# Variational calculation of nuclear matter in finite particle number approach using unitary correlation operator and high-momentum pair methods

## TL;DR

This paper introduces a novel variational approach combining unitary correlation operators and high-momentum pairs to accurately model nuclear matter with finite particles, matching results from established methods.

## Contribution

It develops a new 'UCOM+HM' variational framework for nuclear matter that effectively incorporates short-range correlations and high-momentum excitations, improving upon previous models.

## Key findings

- Results are consistent with Brueckner-Hartree-Fock calculations.
- Method accurately describes symmetric nuclear and neutron matter.
- Converges with increasing 2p2h configurations.

## Abstract

We propose a new variational method for describing nuclear matter from nucleon-nucleon interaction. We use the unitary correlation operator method (UCOM) for central correlation to treat the short-range repulsion and further include the two-particle two-hole (2p2h) excitations of nucleon pair involving a large relative momentum, which is called 'high-momentum pair'(HM). We describe nuclear matter in finite size with finite particle number on periodic boundary condition and increase the 2p2h configurations until we get the convergence of the total energy per particle. We demonstrate the validity of this 'UCOM+HM' framework by applying it to the symmetric nuclear and neutron matters with the Argonne V4$^\prime$ potential having short-range repulsion. The nuclear equations of state obtained in UCOM+HM are fairly consistent to those of other calculations such as Brueckner-Hartree-Fock and auxiliary field diffusion Monte Carlo in the overall density region.