Shining ALP Dark Radiation

7 Oct 2021  ·  Joerg Jaeckel, Wen Yin ·

String scenarios typically not only predict axion-like particles (ALPs) but also significant amounts of ALP dark radiation originating from the decay of the inflaton or a more general modulus. In this paper, we study the decay of such non-thermally produced relativistic (but massive) ALPs to photons... If the ALPs are sufficiently highly energetic, contribute to $\Delta N_{\rm eff} \gtrsim {\cal O}(0.001)$ and have a mass $m_a\gtrsim$ MeV we find that, using observations of X-, and $\gamma$-rays, the CMB and BBN, very small values of the ALP-photon coupling can be probed, corresponding to an origin of this coupling at the string (or even Planck) scale. read more

PDF Abstract
No code implementations yet. Submit your code now

Categories


High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics High Energy Physics - Experiment