Microscopic Analysis of Order Parameters in Nuclear Quantum Phase Transitions

TL;DR

This paper investigates nuclear shape phase transitions in Nd isotopes by analyzing excitation spectra and wave functions, revealing sharp discontinuities at N=90 indicative of a first-order quantum phase transition.

Contribution

It introduces a microscopic approach using a five-dimensional Hamiltonian with parameters from relativistic mean-field calculations to study shape transitions.

Findings

Energy gaps show sharp discontinuities at N=90.

Isomer shifts exhibit abrupt changes at the transition.

Monopole transition strengths peak at the critical point.

Abstract

Microscopic signatures of nuclear ground-state shape phase transitions in Nd isotopes are studied using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. As a function of the physical control parameter -- the number of nucleons, energy gaps between the ground state and the excited vibrational states with zero angular momentum, isomer shifts, and monopole transition strengths, exhibit sharp discontinuities at neutron number N=90, characteristic of a first-order quantum phase transition.