Models with Peccei-Quinn symmetry and vector-like quarks realize one-loop proton decay through the operator u_R u_R d_R e_R while preserving a residual Z2 that forbids tree-level decay, yielding testable axion-photon couplings and an axion-accompanied decay mode.
Isocurvature bounds on axions revisited
2 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The axion is one of the best motivated candidates for particle dark matter. We study and update the constraints imposed by the recent CMB and LSS experiments on the mass of axions produced by the misalignment mechanism, as a function of both the inflationary scale and the reheating temperature. Under some particular although not unconventional assumptions, the axionic field induces too large isocurvature perturbations. Specifically, for inflation taking place at intermediate energy scales, we derive some restrictive limits which can only be evaded by assuming an efficient reheating mechanism, with T>10^{11} GeV. Chaotic inflation with a quadratic potential is still compatible with the axion scenario, provided that the Peccei-Quinn scale f_a is close to 10^{10} or 10^{11} GeV. Isocurvature bounds eliminate the possibility of a larger f_a and a small misalignment angle. We find that isocurvature constraints on the axion scenario must be taken into account whenever the scale of inflation is above 10^{12} GeV; below this scale, axionic isocurvature modes are too small to be probed by current observations.
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Review classifies QCD axion models extending the standard mass-coupling window and updates bounds from cosmology, astrophysics, and experiments.
citing papers explorer
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One-loop proton decay from Peccei-Quinn symmetry
Models with Peccei-Quinn symmetry and vector-like quarks realize one-loop proton decay through the operator u_R u_R d_R e_R while preserving a residual Z2 that forbids tree-level decay, yielding testable axion-photon couplings and an axion-accompanied decay mode.
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The landscape of QCD axion models
Review classifies QCD axion models extending the standard mass-coupling window and updates bounds from cosmology, astrophysics, and experiments.