# Spectroscopy of odd-odd nuclei within the interacting boson-fermion-fermion model based on the Gogny energy density functional

## TL;DR

This paper develops a microscopic method to calculate the spectroscopic properties of odd-odd nuclei using the interacting boson-fermion-fermion model with inputs from Gogny energy density functional calculations, successfully applied to gold isotopes.

## Contribution

It introduces a new approach combining self-consistent mean-field calculations with the IBFFM to reduce free parameters and accurately reproduce experimental spectra.

## Key findings

- Accurately describes low-energy spectra of $^{194,196,198}$Au.
- Reduces free parameters in IBFFM by using microscopic inputs.
- Successfully reproduces electromagnetic transition rates.

## Abstract

We present a method to calculate spectroscopic properties of odd-odd nuclei within the framework of the Interacting Boson-Fermion-Fermion Model based on the Gogny energy density functional. The $(\beta,\gamma)$-deformation energy surface of the even-even (boson-)core nucleus, spherical single-particle energies and occupation probabilities of the odd neutron and odd proton, are provided by the constrained self-consistent mean-field calculation within the Hartree-Fock-Bogoliubov method with the Gogny-D1M functional. These quantities are used as a microscopic input to fix most of the parameters of the IBFFM Hamiltonian. Only a few coupling constants for the boson-fermion Hamiltonian and the residual neutron-proton interaction are specifically adjusted to reproduce experimental low-energy spectra in odd-mass and odd-odd nuclei, respectively. In this way, the number of free parameters involved in the IBFFM framework is reduced significantly. The method is successfully applied to the description of the low-energy spectra and electromagnetic transition rates in the odd-odd $^{194,196,198}$Au nuclei.