TY - JOUR
T1 - Saving the invisible axion
AU - Steinhardt, Paul J.
AU - Turner, Michaek S.
N1 - Funding Information:
This work was supported in part by the DOE through contracts ACO2 80ER10773 A003 (at Chicago) and EY-76-C-02-3071 (at Penn). PJS is also supported by a DOE outstanding junior investigator grant.
PY - 1983/9/15
Y1 - 1983/9/15
N2 - Recently it has been shown that the energy density contributed today by coherent oscillations of the invisible axion field corresponds to Ω {reversed tilde equals} 0.1 ( f{hook}a 1012 GeV) 11 9 (f{hook}a is the scale of peccei-Quinn SSB), apparently ruling out f{hook}a ≳ O(1013 GeV). We propose a simple way to avoid this bound: entropy production when the temperature of the universe is between about 1 GeV and 1 MeV. The entropy might be produced by a first-order phase transition, or the out-of-equilibrium decays of a relic particle species. For f{hook}a {reversed tilde equals} 1015 GeV, the entropy of the universe must be increased by a factor of O(102-103) to have Ωa {reversed tilde equals} O(1). If inflation also occurs at a temperature {reversed tilde equals}1015 GeV, then the de Sitter space produced fluctuations in the axion field lead to a Zel'dovich-like spectrum of (isothermal) perturbations in the axion energy density, with amplitude about 10-4. It has recently been argued that in an axion-dominated universe such a spectrum could lead to the formation of of the structure observed in the universe today.
AB - Recently it has been shown that the energy density contributed today by coherent oscillations of the invisible axion field corresponds to Ω {reversed tilde equals} 0.1 ( f{hook}a 1012 GeV) 11 9 (f{hook}a is the scale of peccei-Quinn SSB), apparently ruling out f{hook}a ≳ O(1013 GeV). We propose a simple way to avoid this bound: entropy production when the temperature of the universe is between about 1 GeV and 1 MeV. The entropy might be produced by a first-order phase transition, or the out-of-equilibrium decays of a relic particle species. For f{hook}a {reversed tilde equals} 1015 GeV, the entropy of the universe must be increased by a factor of O(102-103) to have Ωa {reversed tilde equals} O(1). If inflation also occurs at a temperature {reversed tilde equals}1015 GeV, then the de Sitter space produced fluctuations in the axion field lead to a Zel'dovich-like spectrum of (isothermal) perturbations in the axion energy density, with amplitude about 10-4. It has recently been argued that in an axion-dominated universe such a spectrum could lead to the formation of of the structure observed in the universe today.
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U2 - 10.1016/0370-2693(83)90727-X
DO - 10.1016/0370-2693(83)90727-X
M3 - Article
AN - SCOPUS:0002466533
SN - 0370-2693
VL - 129
SP - 51
EP - 56
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
IS - 1-2
ER -