An ab initio theory of double odd-even mass differences in nuclei

TL;DR

This paper develops an ab initio theoretical framework to evaluate double odd-even mass differences in semi-magic nuclei, considering superfluid and non-superfluid components with a semi-microscopic pairing interaction model.

Contribution

It introduces a unified approach for calculating D_2 in nuclei by combining first-principles and phenomenological methods for different nuclear subsystems.

Findings

D_2 approximately equals 2Δ in superfluid nuclei

D_2 in non-superfluid nuclei derived from two-particle Green function

Semi-microscopic model with a universal phenomenological parameter

Abstract

Two aspects of the problem of evaluating double odd-even mass differences D_2 in semi-magic nuclei are studied related to existence of two components with different properties, a superfluid nuclear subsystem and a non-superfluid one. For the superfluid subsystem, the difference D_2 is approximately equal to 2\Delta, the gap \Delta being the solution of the gap equation. For the non-superfluid subsystem, D_2 is found by solving the equation for two-particle Green function for normal systems. Both equations under consideration contain the same effective pairing interaction. For the latter, the semi-microscopic model is used in which the main term calculated from the first principles is supplemented with a small phenomenological addendum containing one phenomenological parameter supposed to be universal for all medium and heavy atomic nuclei.