The strong CP problem and higher-dimensional gauge theories. (22nd April 2022)

• Record Type: Journal Article
• Authors: Adachi, Yuki; Lim, C S; Maru, Nobuhito
• Is Part Of: Progress of theoretical and experimental physics. Volume 2022:Number 5(2022)
• Publication Date: 2022-04-22
• Subjects: Physics -- Periodicals; Mathematical physics -- Periodicals; 530.05
• DOI: 10.1093/ptep/ptac070
• Languages: English
• ISSNs: 2050-3911

Abstract

Abstract: We discuss a natural scenario to solve the strong CP problem in the framework of the higher-dimensional gauge theory. An axion-like field Ay has been built in as the extra-space component of the higher-dimensional gauge field. The coupling of Ay with gluons is attributed to the radiatively induced "Chern–Simons" (CS) term. We adopt a toy model with some unknown gauge symmetry U(1)X . The CS term is obtained in two ways: first by a concrete 1-loop calculation and next by use of Fujikawa's method to deal with the chiral anomaly in 4D space-time. The obtained results are identical, which implies that the radiative correction to the CS term is "1-loop exact" and is also free from UV-divergence even though the theory itself is non-renormalizable. As a novel feature of this scenario, the thus-obtained CS term is no longer linear in the field Ay as in the usually discussed CS term in 5D space-time but is a periodic function of Ay, since Ay has a physical meaning as the Wilson-loop phase. We argue how such a novel feature in this scenario causes modification of the ordinary solutions of the strong CP problem based on the axion fields.