Spontaneous CPT Violation and Quantum Anomalies in a Model for Matter-Antimatter Asymmetry in the Cosmos

TL;DR

This paper reviews a string-inspired model for matter-antimatter asymmetry involving spontaneous CPT violation via a Kalb-Ramond axion background, exploring its implications for leptogenesis and quantum anomalies in the early universe.

Contribution

It introduces a novel scenario where a temperature-dependent Kalb-Ramond axion background causes spontaneous CPT violation, affecting leptogenesis and quantum anomaly effects in the Standard Model extension.

Findings

KR axion background does not contribute to the chiral magnetic effect.

Quantum fluctuations of the KR axion may generate Majorana masses for right-handed neutrinos.

The model links string-inspired CPT violation to matter-antimatter asymmetry.

Abstract

We review scenarios of baryogenesis through leptogenesis at early epochs of the universe, in string-inspired minimal extensions of the Standard Model (SM), involving heavy right-handed Majorana neutrinos. Spontaneous violation of CPT symmetry is induced by appropriate (in general, temperature-dependent) backgrounds of the Kalb-Ramond (KR) axion field, which has its origins in the (bosonic) massless string multiplet. As interesting features of the model, we also discuss two issues associated with quantum (chiral) anomalies: (i) the non-contribution of the KR axion background to the (anomalous) chiral magnetic effect, which arises in the presence of external electromagnetic fields and non-zero chiral chemical potentials of charged fermions and (ii) the potential r\^ole of quantum fluctuations of the KR axion on the (anomalous) radiative generation of a Majorana mass for the right-handed neutrinos themselves.