Using $\Delta N_{\rm eff}$ to constrain preferred axion model dark matter
Using $\Delta N_{\rm eff}$ to constrain preferred axion model dark matter
天文学
Andrew Cheek,Ui Min.Using $\Delta N_{\rm eff}$ to constrain preferred axion model dark matter[EB/OL].(2024-11-26)[2025-10-25].https://arxiv.org/abs/2411.17320.点此复制
Preferred axion models are minimal realizations of the Peccei-Quinn solution
to the strong CP problem while providing a dark matter candidate. These models
invoke new heavy quarks that interact strongly with the Standard Model bringing
them into thermal equilibrium in the early Universe. We show that for a number
of these models, the heavy quarks will decay after axions have decoupled from
the Standard Model thermal bath. As a consequence, any axion products in the
decay form a component of dark radiation. This provides the potential to
differentiate between preferred axion models through measurements of the number
of relativistic degrees of freedom. The most sensitive of which comes from the
Planck collaboration's measurements of the Cosmic Microwave Background. We find
that existing constraints allow us to rule out regions of parameter space for
40% of the canonical preferred axion models.
展开英文信息
评论