Coupled Boltzmann computation of mixed axion neutralino dark matter in the SUSY DFSZ axion model

Journal Article · Wed Oct 01 04:00:00 EDT 2014 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2014/10/082· OSTI ID:22375724

Bae, Kyu Jung; Baer, Howard; Serce, Hasan ^[1]; Lessa, Andre ^[2]

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1. Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks, Norman, OK 73019 (United States)
2. Instituto de Física, Universidade de São Paulo, São Paulo – SP (Brazil)

The supersymmetrized DFSZ axion model is highly motivated not only because it offers solutions to both the gauge hierarchy and strong CP problems, but also because it provides a solution to the SUSY μ-problem which naturally allows for a Little Hierarchy. We compute the expected mixed axion-neutralino dark matter abundance for the SUSY DFSZ axion model in two benchmark cases—a natural SUSY model with a standard neutralino underabundance (SUA) and an mSUGRA/CMSSM model with a standard overabundance (SOA). Our computation implements coupled Boltzmann equations which track the radiation density along with neutralino, axion, axion CO (produced via coherent oscillations), saxion, saxion CO, axino and gravitino densities. In the SUSY DFSZ model, axions, axinos and saxions go through the process of freeze-in—in contrast to freeze-out or out-of-equilibrium production as in the SUSY KSVZ model—resulting in thermal yields which are largely independent of the re-heat temperature. We find the SUA case with suppressed saxion-axion couplings (ξ=0) only admits solutions for PQ breaking scale f{sub a}∼< 6× 10{sup 12} GeV where the bulk of parameter space tends to be axion-dominated. For SUA with allowed saxion-axion couplings (ξ =1), then f{sub a} values up to ∼ 10{sup 14} GeV are allowed. For the SOA case, almost all of SUSY DFSZ parameter space is disallowed by a combination of overproduction of dark matter, overproduction of dark radiation or violation of BBN constraints. An exception occurs at very large f{sub a}∼ 10{sup 15}–10{sup 16} GeV where large entropy dilution from CO-produced saxions leads to allowed models.

• OSTI ID: 22375724
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 10 Vol. 2014; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTRONOMY AND ASTROPHYSICS
AXIONS
BOLTZMANN EQUATION
CALCULATION METHODS
ENTROPY
FREEZING OUT
MATHEMATICAL SOLUTIONS
NONLUMINOUS MATTER
SUPERSYMMETRY