A solution to the strong CP problem from mirror QCD and chiral U(1)

by Prof. Keisuke Harigaya (the University of Chicago)

Thursday 25 Jun 2026, 11:00 → 12:00 Asia/Shanghai

Tsung-Dao Lee Institute/N6F-N600 - Lecture Room (Tsung-Dao Lee Institute)

Abstract:

We present a solution to the strong CP problem in which a simple chiral U(1) gauge symmetry gives rise to an accidental Peccei-Quinn symmetry. The Peccei-Quinn symmetry is both explicitly and spontaneously broken by mirror QCD dynamics, yielding a framework without an axion quality problem. The model contains no stable domain walls or colored relics, and it accommodates a sufficiently high reheating temperature to account for the baryon asymmetry of the Universe via leptogenesis. Metastable domain walls generate a stochastic background of primordial gravitational waves. Additionally, one of the pseudo-Nambu-Goldstone bosons serves as a viable WIMP dark matter candidate, while colored pseudo-Nambu-Goldstone bosons can be probed at the LHC through searches for jets plus missing energy, multi jets plus leptons, and displaced vertices. 

Biography:

Keisuke Harigaya received his PhD in physics from the University of Tokyo, held postdoctoral positions at the UC Berkeley, the Institute for Advanced Study, and CERN, and joined the University of Chicago as a faculty member in 2022. He studies theoretical particle physics and cosmology. 

Alternative online link: https://meeting.tencent.com/dm/NhkVPyarSSeo

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