Cosmological axion and a quark nugget dark matter model

We study a dark matter (DM) model offering a very natural explanation of two (naively unrelated) problems in cosmology: the observed relation Ω_DM∼Ω_visible and the observed asymmetry between matter and antimatter in the Universe, known as the "baryogenesis" problem. In this framework, both types of matter (dark and visible) have the same QCD origin, form at the same QCD epoch, and are proportional to one and the same dimensional parameter of the system, Λ_QCD, which explains how these two naively distinct problems could be intimately related, and could be solved simultaneously within the same framework. More specifically, the DM in this model is composed by two different ingredients: the (well-studied) DM axions and the (less-studied) quark nuggets made of matter or antimatter. We focus on the quantitative analysis of the relation between these two distinct components contributing to the dark sector of the theory determined by Ω_DM≡[Ω_DM(nuggets)+Ω_DM(axion)] . We argue that the nuggets' DM component always traces the visible matter density, i.e., Ω_DM(nuggets)∼Ω_visible , and this feature is not sensitive to the parameters of the system such as the axion mass m_a or the misalignment angle θ₀. It should be contrasted with conventional axion production mechanisms due to the misalignment when Ω_DM(axion) is highly sensitive to the axion mass m_a and the initial misalignment angle θ₀. We also discuss the constraints on this model related to the inflationary scale H_I, nonobservation of the isocurvature perturbations and the tensor modes. We also comment on some constraints related to various axion search experiments.