TY - JOUR

T1 - Spectrum of the axion dark sector

AU - Stott, Matthew J.

AU - Marsh, David J.E.

AU - Pongkitivanichkul, Chakrit

AU - Price, Layne C.

AU - Acharya, Bobby S.

PY - 2017/10/15

Y1 - 2017/10/15

N2 - 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∼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.

AB - 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∼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.

UR - http://www.scopus.com/inward/record.url?scp=85033231543&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.96.083510

DO - 10.1103/PhysRevD.96.083510

M3 - Article

AN - SCOPUS:85033231543

SN - 2470-0010

VL - 96

SP - 083510-1 - 083510-39

JO - Physical Review D (Particles, Fields, Gravitation and Cosmology)

JF - Physical Review D (Particles, Fields, Gravitation and Cosmology)

IS - 8

M1 - 083510

ER -