Contributions to $\mathrm{\Delta }{N}_{\mathrm{eff}}$ from the dark photon of $U(1{)}_{T3R}$

Journal Article · Thu Jul 16 00:00:00 EDT 2020 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.102.015013· OSTI ID:1638767

Dutta, Bhaskar; Ghosh, Sumit ; Kumar, Jason

We consider the effect on early Universe cosmology of the dark photon associated with the gauging of U(1)_T3R, a symmetry group under which only right-handed Standard Model fermions transform nontrivially. We find that cosmological constraints on this scenario are qualitatively much more severe than on other well-studied cases of a new U(1) gauge group, because the dark photon couples to chiral fermions. In particular, the dark photon of U(1)_T3R is always produced and equilibrates in the early Universe, no matter how small the gauge coupling, unless the symmetry-breaking scale is extremely large. This occurs because, no matter how the weak the coupling, the Goldstone mode (equivalently, the longitudinal polarization) does not decouple. As a result, even the limit of an extremely light and weakly coupled dark photon of U(1)_T3R is effectively ruled out by cosmological constraints, unless the symmetry-breaking scale is extremely large. We also discuss the possibility of ameliorating the Hubble tension in this model.

• Research Organization: Univ. of Hawaii, Honolulu, HI (United States). High Energy Physics Group
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC0010813; SC0010504
• OSTI ID: 1638767
• Alternate ID(s): OSTI ID: 1780920
• Journal Information: Physical Review D, Journal Name: Physical Review D Vol. 102 Journal Issue: 1; ISSN 2470-0010
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS