Cosmic birefringence from CP-violating axion interactions

A bstract We explore the cosmic birefringence signal produced by an ultralight axion field with a small CP-violating coupling to bulk SM matter in addition to the usual CP-preserving photon coupling. The change in the vacuum expectation value of the field between recombination and today results in a...

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Bibliographic Details
Published in:The journal of high energy physics 2024-08, Vol.2024 (8), p.38-16, Article 38
Main Authors: Luo, Xuheng, Mathur, Anubhav
Format: Article
Language:English
Subjects:
Atoms & subatomic particles
Axions and ALPs
Birefringence
Bulk density
Classical and Quantum Gravitation
Cosmology of Theories BSM
Couplings
CP violation
Dark energy
Dark matter
Dipole interactions
Early Universe Particle Physics
Elementary Particles
Hypothetical particles
Initial conditions
Linear polarization
New Light Particles
Physics
Physics and Astronomy
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
String Theory
Universe
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Summary:A bstract We explore the cosmic birefringence signal produced by an ultralight axion field with a small CP-violating coupling to bulk SM matter in addition to the usual CP-preserving photon coupling. The change in the vacuum expectation value of the field between recombination and today results in a frequency-independent rotation of the plane of CMB linear polarization across the entire sky. While many previous approaches rely on the axion rolling from a large initial expectation value, the couplings considered in this work robustly generate the birefringence signal regardless of initial conditions, by sourcing the field from the cosmological nucleon density. We place bounds on such monopole-dipole interactions using measurements of the birefringence angle from Planck and WMAP data, which improve upon existing constraints by up to three orders of magnitude. We also discuss UV completions of this model, and possible strategies to avoid fine-tuning the axion mass.
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP08(2024)038