Nelson-Barr relaxion

Davidi, Oz; Gupta, Rick S.; Perez, Gilad; Redigolo, Diego; Shalit, Aviv

Abstract

Cosmological relaxation models in which the relaxion is identified with the QCD axion, generically fail to account for the smallness of the strong C P phase. We present a simple alternative solution to this “relaxion C P problem” based on the Nelson-Barr mechanism. We take C P to be a symmetry of the UV theory, and the relaxion to have no anomalous coupling with QCD. The nonzero vacuum expectation value of the relaxion breaks C P spontaneously, and the resulting phase is mapped to the Cabibbo-Kobayashi-Maskawa phase of the Standard Model. The extended Nelson-Barr quark sector generates the relaxion “rolling” potential radiatively, relating the new physics scale with the relaxion decay constant. With no new states within the reach of the LHC, our relaxion can still be probed in a variety of astrophysical and cosmological processes, as well as in flavor experiments.

Citation

Davidi, O., Gupta, R. S., Perez, G., Redigolo, D., & Shalit, A. (2019). Nelson-Barr relaxion. Physical Review D, 99(3), Article 035014. https://doi.org/10.1103/physrevd.99.035014

• Journal Article Type: Article
• Online Publication Date: Feb 12, 2019
• Publication Date: Feb 1, 2019
• Deposit Date: Feb 19, 2019
• Publicly Available Date: Feb 19, 2019
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 99
• Issue: 3
• Article Number: 035014
• DOI: https://doi.org/10.1103/physrevd.99.035014
• Public URL: https://durham-repository.worktribe.com/output/1337435