Role of the tensor interaction in He isotopes with a tensor-optimized shell model

TL;DR

This paper investigates the influence of tensor interactions on helium isotopes using the tensor-optimized shell model combined with UCOM, revealing how tensor forces affect energy splittings and state configurations.

Contribution

It introduces a systematic study of tensor effects in He isotopes with TOSM+UCOM, utilizing a realistic nucleon-nucleon interaction to clarify tensor contributions to nuclear spectra.

Findings

Tensor interaction enhances LS splitting in 5He.

Tensor contribution increases in low-lying states of 6-8He with neutrons in p3/2.

Pauli-blocking reduces tensor effects in excited states with neutrons in p1/2.

Abstract

We studied the role of the tensor interaction in He isotopes systematically on the basis of the tensor-optimized shell model (TOSM). We use a bare nucleon-nucleon interaction AV8 obtained from nucleon-nucleon scattering data. The short-range correlation is treated in the unitary correlation operator method (UCOM). Using the TOSM+UCOM approach, we investigate the role of tensor interaction on each spectrum in He isotopes. It is found that the tensor interaction enhances the LS splitting energy observed in 5He, in which the p1/2 and p3/2 orbits play different roles on the tensor correlation. In {6,7,8}He, the low-lying states containing extra neutrons in the p3/2 orbit gain the tensor contribution. On the other hand, the excited states containing extra neutrons in the p1/2 orbit lose the tensor contribution due to the Pauli-blocking effect with the 2p2h states in the 4He core configuration.