Bubble Nucleation with Chern-Simons Interaction

13 Mar 2025
Seminars and colloquia
Time
-
Venue
Simpkins Lee Seminar Room
Beecroft Building, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU
Speaker(s)

Dr Saquib Hassan, Oxford U., Theor. Phys.

Seminar series
Dalitz seminar
For more information contact

Abstract

We study axion electrodynamics, including the Chern-Simons interaction term, in the presence of parallel background electric and magnetic fields. In this setup, we find a new back-reacted instanton solution which corresponds to the nucleation of an axion domain wall that screens the electromagnetic fields in a process analogous to Schwinger pair production, despite the absence of light charged particles. The full solution includes the effect of the Chern-Simons induced charges and currents on the axion domain wall arising from the Witten and Sikivie (anomalous Hall) effects, respectively. The Euclidean solution has a reduced O(2)×O(2) symmetry which describes the nucleation of a prolate bubble in its rest-frame. A unique feature of this solution is that the region of lower energy density is outside the bubble rather than inside.