Journal of High Energy Physics

, 2013:214

The cosmophenomenology of axionic dark radiation


DOI: 10.1007/JHEP10(2013)214

Cite this article as:
Conlon, J.P. & Marsh, M.C.D. J. High Energ. Phys. (2013) 2013: 214. doi:10.1007/JHEP10(2013)214


Relativistic axions are good candidates for the dark radiation for which there are mounting observational hints. The primordial decays of heavy fields produce axions which are ultra-energetic compared to thermalised matter and inelastic axion-matter scattering can occur with ECoMTγ, thus accessing many interesting processes which are otherwise kinematically forbidden in standard cosmology. Axion-photon scattering into quarks and leptons during BBN affects the light element abundances, and bounds on over-production of 4He constrain a combination of the axion decay constant and the reheating temperature. For supersymmetric models, axion scattering into visible sector superpartners can give direct non-thermal production of dark matter at TγTfreezeout. Most axions — or any other dark radiation candidate from modulus decay — still linger today as a Cosmic Axion Background with Eaxion ~ \( \mathcal{O} \)(100) eV, and a flux of ~ 106 cm−2 s−1.


Cosmology of Theories beyond the SM Supersymmetric Effective Theories 

Copyright information

© SISSA, Trieste, Italy 2013

Authors and Affiliations

  1. 1.Rudolf Peierls Center for Theoretical PhysicsOxfordU.K.

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