2017/06/10 by Matthew J. Stott, David J. E. Marsh, Chakrit Pongkitivanichkul +3
Mathematics · Physics and Astronomy · #Algorithm #Astrophysics #Axion #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark matter #Effective field theory #Hyperparameter #Mathematics #Moduli #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum mechanics #Statistical physics #String (physics) #String theory #Theoretical physics #astro-ph.CO #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.96.083510
published as Phys. Rev. D 96, 083510 (2017) · 39 pages, 28 figures, 2 tables
arxiv created 2017/06/10 · openalex publication_date 2017/10/11 · arxiv updated 2017/10/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Axions arise in many theoretical extensions of the Standard Model of particle physics, in particular the ``string axiverse.'' If the axion masses, ma, and (effective) decay constants, fa, lie in specific ranges, then axions contribute to the cosmological dark matter and dark energy densities. We compute the background cosmological (quasi)observables for models with a large number of axion fields, nax\ensuremath∼O(10--100), with the masses and decay constants drawn from statistical distributions. This reduces the number of parameters from 2nax to a small number of ``hyperparameters.'' We consider a number of distributions, from those motivated purely by statistical considerations to those where the structure is specified according to a class of M-theory models. Using Bayesian methods, we are able to constrain the hyperparameters of the distributions. In some cases, the hyperparameters can be related to string theory, e.g., constraining the number ratio of axions to moduli, or the typical decay constant scale needed to provide the correct relic densities. Our methodology incorporates the use of both random matrix theory and Bayesian networks.