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arXiv · hep-ph/9909282

Photon Production of Axionic Cold Dark Matter

Da-Shin Lee·Kin-Wang Ng
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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.

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Da-Shin Lee, Kin-Wang Ng. 1999-09-08. Photon Production of Axionic Cold Dark Matter. https://doi.org/10.1103/physrevd.61.085003

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