Speaker
Nils A. Nilsson
Description
Recently, a CMB signal of parity violation in the form of isotropic cosmic birefringence has been claimed, a signal consistent with being produced through an axion-photon coupling. In this talk, I will introduce a generic EFT constructed for studies of spacetime-symmetry breaking. Focusing on the photon sector, I will show that a CPT-odd EFT term in fact takes the same form as an axion-photon coupling and that the non-zero cosmic-birefringence angle produces the strongest constraint on this EFT coefficient to date.
