Photon Production of Axionic Cold Dark Matter
Abstract
Using the non-equilibrium quantum field theory, photon production from the coherently oscillating axion field in a flat Robertson-Walker cosmology is re-examined. First neglecting the Debye screening of the baryon plasma to photons, we find that the axions will dissipate into photons via spinodal instability in addition to parametric resonance. As a result of the pseudo-scalar nature of the axion-photon coupling, we observe a circular polarization asymmetry in the produced photons. However, these effects are suppressed to an insignificant level in the expanding universe. We then briefly discuss a systematic way of including the plasma effect which can further suppress the photon production. We note that the formalism of the problem can be applied to any pseudo-scalar field coupled to photon in a thermal background in a general curved spacetime.
Cite
@article{arxiv.hep-ph/9909282,
title = {Photon Production of Axionic Cold Dark Matter},
author = {Da-Shin Lee and Kin-Wang Ng},
journal= {arXiv preprint arXiv:hep-ph/9909282},
year = {2009}
}
Comments
17 pages, RevTex, including 5 ps figures