Nuclear Schiff moment and soft vibrational modes

TL;DR

This paper explores how soft vibrational modes in nuclei can enhance the nuclear Schiff moment, which is crucial for understanding atomic electric dipole moments and CP violation, beyond static deformation effects.

Contribution

It introduces a new mechanism for Schiff moment enhancement via soft vibrational modes, supported by analytical and numerical analysis.

Findings

Soft vibrational modes can enhance the Schiff moment.

Analytical and numerical methods confirm the enhancement.

Implications for nuclear structure studies beyond mean-field approximations.

Abstract

The atomic electric dipole moment (EDM) currently searched by a number of experimental groups requires that both parity and time-reversal invariance be violated. According to current theoretical understanding, the EDM is induced by the nuclear Schiff moment. The enhancement of the Schiff moment by the combination of static quadrupole and octupole deformation was predicted earlier. Here we study a further idea of the possible enhancement in the absence of static deformation but in a nuclear system with soft collective vibrations of two types. Both analytical approximation and numerical solution of the simplified problem confirm the presence of the enhancement. We discuss related aspects of nuclear structure which should be studied beyond mean-field and random phase approximations.