Opening up the QCD axion window
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13130_2018_Article_7761.pdf
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2.08 MB
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Author(s)
Agrawal, Prateek
Marques-Tavares, Gustavo
Xue, Wei
Date Issued
March 2018
Journal
Journal of High Energy Physics
Publisher
Springer Berlin Heidelberg
Citation
Agrawal, Prateek, et al. “Opening up the QCD Axion Window.” Journal of High Energy Physics, vol. 2018, no. 3, Mar. 2018. © 2018 The Authors
Version
Final published version
Abstract
We present a new mechanism to deplete the energy density of the QCD axion, making decay constants as high as fa ≃ 1017 GeV viable for generic initial conditions. In our setup, the axion couples to a massless dark photon with a coupling that is moderately stronger than the axion coupling to gluons. Dark photons are produced copiously through a tachyonic instability when the axion field starts oscillating, and an exponential suppression of the axion density can be achieved. For a large part of the parameter space this dark radiation component of the universe can be observable in upcoming CMB experiments. Such dynamical depletion of the axion density ameliorates the isocurvature bound on the scale of inflation. The depletion also amplifies the power spectrum at scales that enter the horizon before particle production begins, potentially leading to axion miniclusters.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1007/JHEP03(2018)049
