Isospin Mixing and the Cubic Isobaric Multiplet Mass Equation in the Lowest T = 2, A = 32 Quintet

TL;DR

This study investigates the breakdown of the isobaric multiplet mass equation in the T=2, A=32 quintet, attributing it to isospin mixing with nonanalog states, supported by experimental data and advanced shell-model calculations.

Contribution

It combines experimental data with shell-model calculations to identify isospin mixing as the cause of IMME breakdown in the A=32 quintet.

Findings

Isospin mixing with nonanalog T=1 states causes IMME violation.

Shell-model calculations validate isospin-mixing matrix elements.

An anomalous cubic term is necessary for the multiplet.

Abstract

The isobaric multiplet mass equation (IMME) is known to break down in the first T = 2, A = 32 isospin quintet. In this work we combine high-resolution experimental data with state-of-the-art shell-model calculations to investigate isospin mixing as a possible cause for this violation. The experimental data are used to validate isospin-mixing matrix elements calculated with newly developed shell-model Hamiltonians. Our analysis shows that isospin mixing with nonanalog T = 1 states contributes to the IMME breakdown, making the requirement of an anomalous cubic term inevitable for the multiplet.