Opening the 1$\,$Hz axion window.

摘要: An axion-like particle (ALP) with mass $m_\phi \sim 10^{-15}$eV oscillates frequency $\sim$1 Hz. This scale lies in an open window of astrophysical constraints, and appears naturally as a consequence grand unification (GUT) string/M-theory. However, GUT-scale decay constant such ALP overcloses the Universe, cannot solve strong CP problem. In this paper, we present two axion model which 1 Hz constitutes entirety dark matter (DM) while QCD solves problem but contributes negligibly to DM relic density. The mechanism achieve correct densities relies on low-scale inflation ($m_\phi \lesssim H_{\rm inf}\lesssim 1$ MeV), explicit realisations model. potential leading generates value for phase around $\bar{\theta}_{\rm QCD}\sim 10^{-12}$, within reach proton storage ring electric dipole moment experiment. is also near future laboratory searches.