Work

High reheating temperature without axion domain walls

Year: 2026

Type: article

Abstract: We investigate a cosmological scenario in which the Peccei-Quinn (PQ) symmetry remains broken in the entire history of the Universe, thereby avoiding the formation of axion strings and domain walls. Contrary to the conventional expectation, it is demonstrated that appropriately chosen scalar interactions are able to keep the PQ symmetry broken at arbitrarily high temperatures. We carefully examine the finite-temperature effective potential in a model with two PQ breaking scalar fields. The existence of flat directions plays a vital role in suppressing axion isocurvature perturbations during inflation by stabilizing a PQ field at a large field value. The viable parameter space consistent with theoretical and observational constraints is identified. Our scenario provides a minimal path for PQ symmetry breaking that addresses both the axion domain wall and isocurvature problems while permitting arbitrarily high reheating temperatures accommodating high-scale baryogenesis scenarios such as thermal leptogenesis.

Source: Physics Letters B

DOI: 10.1016/j.physletb.2026.140177

Authors: Shota Nakagawa, Yuichiro Nakai, Yu-Cheng Qiu, Lingyun Wang, Yaoduo Wang

Institutions: Shanghai Jiao Tong University, City University of Hong Kong, Wuhan University

Language: English

Topic: Particle physics theoretical and experimental studies

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond

Funders: Glaucoma Research Foundation, Natural Science Foundation of Shanghai, City University of Hong Kong

Awards: G3734235842, G5299299992