TY - JOUR
T1 - Relaxing isocurvature bounds on string axion dark matter
AU - Kawasaki, Masahiro
AU - Kitajima, Naoya
AU - Takahashi, Fuminobu
N1 - Funding Information:
This work was supported by the Grant-in-Aid for Scientific Research on Innovative Areas (No. 23104008 [F.T.]), JSPS Grant-in-Aid for Young Scientists (B) (No. 24740135 ) [F.T.], Scientific Research (B) (No. 26287039 [FT]), Scientific Research (C) (No. 25400248 [M.K.]), Inoue Foundation for Science [F.T.]. This work was also supported by World Premier International Center Initiative (WPI Program), MEXT , Japan [M.K. and F.T.].
PY - 2014/10/7
Y1 - 2014/10/7
N2 - If inflation scale is high, light scalars acquire large quantum fluctuations during inflation. If sufficiently long-lived, they will give rise to CDM isocurvature perturbations, which are highly constrained by the Planck data. Focusing on string axions as such light scalars, we show that thermal inflation can provide a sufficiently large entropy production to dilute the CDM isocurvature perturbations. Importantly, efficient dilution is possible for the string axions, because effectively no secondary coherent oscillations are induced at the end of thermal inflation, in contrast to the moduli fields. We also study the viability of the axion dark matter with mass of about 7 keV as the origin of the 3.5 keV X-ray line excess, in the presence of large entropy production.
AB - If inflation scale is high, light scalars acquire large quantum fluctuations during inflation. If sufficiently long-lived, they will give rise to CDM isocurvature perturbations, which are highly constrained by the Planck data. Focusing on string axions as such light scalars, we show that thermal inflation can provide a sufficiently large entropy production to dilute the CDM isocurvature perturbations. Importantly, efficient dilution is possible for the string axions, because effectively no secondary coherent oscillations are induced at the end of thermal inflation, in contrast to the moduli fields. We also study the viability of the axion dark matter with mass of about 7 keV as the origin of the 3.5 keV X-ray line excess, in the presence of large entropy production.
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U2 - 10.1016/j.physletb.2014.08.017
DO - 10.1016/j.physletb.2014.08.017
M3 - Article
AN - SCOPUS:84907392096
VL - 737
SP - 178
EP - 184
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
SN - 0370-2693
ER -