2019/01/31 by Shu-Yu Ho, Fuminobu Takahashi, Wen Yin · 3 citations
Physics and Astronomy · #Axion #Cosmological constant #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dilaton #Hubble's law #Inflation (cosmology) #Moduli #Particle physics theoretical and experimental studies #Quantum chromodynamics #String (physics) #String theory #astro-ph.CO #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1007/jhep04(2019)149
19pages, 4figures; v2: version to appear in JHEP
openalex created_date 2019/01/11 · openalex publication_date 2019/04/01 · arxiv created 2019/04/23 · arxiv updated 2019/05/22 · openalex updated_date 2026/08/06
A bstract We show that the cosmological abundance of string axions is much smaller than naive estimates if the Hubble scale of inflation, H inf , is sufficiently low (but can still be much higher than the axion masses) and if the inflation lasts sufficiently long. The reason is that the initial misalignment angles of the string axions follow the Bunch-Davies distribution peaked at the potential minima. As a result, the cosmological moduli problem induced by the string axions can be significantly relaxed by low-scale inflation, and astrophysical and cosmological bounds are satisfied over a wide range of the mass without any fine-tuning of the initial misalignment angles. Specifically, the axion with its decay constant f ϕ = 10 16 GeV satisfies the bounds over 10 −18 eV ≲ m ϕ ≲ 10 TeV for H inf ≲ 10 keV-10 6 GeV. We also discuss cases with multiple axions and the QCD axion.