Continuum discretized BCS approach for weakly bound nuclei

TL;DR

This paper extends the BCS formalism to include the single-particle continuum using a discretized approach, enabling analysis of pairing evolution in weakly bound nuclei near the drip line.

Contribution

It introduces a continuum discretized BCS method based on pseudostates generated from a Transformed Harmonic Oscillator basis, improving analysis of weakly bound nuclear systems.

Findings

Non-resonant continuum significantly influences pairing near the drip line.

The method accurately reproduces experimental data for neutron-rich isotopes.

The continuum occupation evolves notably as nuclei become weakly bound.

Abstract

The Bardeen-Cooper-Schrieffer (BCS) formalism is extended by including the single-particle continuum in order to analyse the evolution of pairing in an isotopic chain from stability up to the drip line. We propose a continuum discretized generalized BCS based on single-particle pseudostates (PS). These PS are generated from the diagonalization of the single-particle Hamiltonian within a Transformed Harmonic Oscillator (THO) basis. The consistency of the results versus the size of the basis is studied. The method is applied to neutron rich Oxygen and Carbon isotopes and compared with similar previous works and available experimental data. We make use of the flexibility of the proposed model in order to study the evolution of the occupation of the low-energy continuum when the system becomes weakly bound. We find a larger influence of the non-resonant continuum as long as the Fermi level approaches zero.