The Triton:Low-momentum Interactions and Off-shell effects

TL;DR

This paper investigates how off-shell effects in nucleon-nucleon interactions influence nuclear properties, demonstrating their significance in the Triton binding energy, scattering, and nuclear matter saturation through theoretical and computational analysis.

Contribution

It shows that off-shell effects are crucial in nuclear interactions and can be adjusted to match experimental data without altering on-shell scattering fits.

Findings

Off-shell effects cause Triton overbinding and can be tuned with short-range repulsion.

Off-shell induced correlations contribute to nuclear saturation and finite nucleus stability.

Theoretical models incorporating off-shell effects align with experimental observations.

Abstract

A microscopic theory of nuclei based on a 'free' scattering NN-potential is meaningful only if this potential fits on-shell scattering data.This is a necessary but not sufficient condition for the theory to be successful.It has been demonstrated repeatedly in the past that 2-body off-shell adjustments or many-body forces are necessary.It has been shown however, using Eff. Field Theory and formal scattering theory, that off-shell and many-body effects can not be separated.This 'equivalence theorem' allows us to concentrate on the off-shell effects.Examples of on-shell equivalent potentials Paris, Bonn etc but here separable potentials are calculated by inverse scattering from NN-scattering and Deuteron data, Earlier calculations showed these S-state potentials to agree with Bonn-B results in Brueckner nuclear matter calculations. They are here also used to compute the Triton binding energy and the n-D scattering length.The results are found to lie on the Phillips line defined in early calculations but like these miss the experimental point on this line and overbind the Triton but is reached by modifying the off-shell properties adding a short-range repulsion without affecting fits to the experimental low-energy phase-shifts.The off-shell induced correlations result in a repulsive component in the Triton effective interactions.In nuclear matter the same effect is referred to as the dispersion correction, which is a main contributor to nuclear saturation.In finite nucleus Brueckner-HF calculations these same correlations give an important contribution to the selfconsistent (reaarangement term), without which the finite nucleus would collapse.The main purpose of the present work is to illustrate that NN-correlations are as important in the Triton as they are in nuclear matter or other finite nuclei.