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QCD Axion Dark Matter with a Small Decay Constant
Raymond T Co1,2,3, Lawrence J Hall2,3, Keisuke Harigaya2,3
1Leinweber Center for Theoretical Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
Abstract:
The QCD axion is a good dark matter candidate. The observed dark matter abundance can arise from misalignment or defect mechanisms, which generically require an axion decay constant f_{a}∼O(10^{11}) GeV (or higher). We introduce a new cosmological origin for axion dark matter, parametric resonance from oscillations of the Peccei-Quinn symmetry breaking field, that requires f_{a}∼(10^{8}-10^{11}) GeV. The axions may be warm enough to give deviations from cold dark matter in large scale structure.
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