Parity Solution to the Strong CP Problem and a Unified Framework for Inflation, Baryogenesis, and Dark Matter

TL;DR

This paper proposes a parity-based solution to the strong CP problem within left-right symmetric theories, unifying explanations for inflation, baryogenesis, and dark matter through a minimal Higgs sector and novel mechanisms involving fermions and scalar fields.

Contribution

It introduces a unified framework connecting parity symmetry, neutrino mass generation, matter-antimatter asymmetry, and dark matter using Affleck-Dine leptogenesis and inflaton decay in left-right symmetric models.

Findings

Lepton asymmetry generated without wash-out effects.

Identification of a fermion as a warm dark matter candidate.

Unified explanation for multiple cosmological puzzles.

Abstract

It has been known for some time that asymptotic parity invariance of weak interactions can provide a solution to the strong CP problem without the need for the axion. Left-right symmetric theories which employ a minimal Higgs sector consisting of a left-handed and a right-handed doublet is an example of such a theory wherein all fermion masses arise through a generalized seesaw mechanism. In this paper we present a way to understand the origin of matter-antimatter asymmetry as well as the dark matter content of the universe in these theories using the Affleck-Dine (AD) leptogenesis mechanism and inflaton decay, respectively. Three gauge singlet fermions are needed for this purpose, two of which help to implement the Dirac seesaw for neutrino masses while the third one becomes the non-thermal warm dark matter candidate. A soft lepton number breaking term involving the AD scalar field is used to generate lepton asymmetry which suffers no wash-out effects and maintains the Dirac nature of neutrinos. This framework thus provides a unified description of many of the unresolved puzzles of the standard model that require new physics.