Cosmological axion and a quark nugget dark matter model

Abstract

We study a dark matter (DM) model offering a very natural explanation of two (naively unrelated) problems in cosmology: the observed relation ΩDM ∼ 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 both proportional to one and the same dimensional parameter of the system, ΛQCD, 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 (less-studied) the quark nuggets made of matter or antimatter. The focus of the present work is the quantitative analysis of the relation between these two distinct components contributing to the dark sector of the theory determined by ΩDM ≡ [ΩDM(nuggets) + ΩDM(axion)]. We argue that the nugget's DM component always traces the visible matter density, i.e. ΩDM(nuggets) ∼ Ω visible and this feature is not sensitive to the parameters of the system such as the axion mass ma or the misalignment angle θ0. It should be contrasted with conventional axion production mechanism due to the misalignment when ΩDM(axion) is highly sensitive to the axion mass ma and the initial misalignment angle θ0. We also discuss the constraints on this model related to the inflationary scale HI , non-observation of the isocurvature perturbations and the tensor modes. We also comment on some constraints related to varies axion search experiments.

New mechanism producing axions in the AQN model and how the CAST can discover them

“…As a result of these CP violating processes the number of nuggets and antinuggets being formed would be different. This difference is always of order one effect [22][23][24] irrespectively to the parameters of the theory, the axion mass m a or the initial misalignment angle θ 0 . As a result of this disparity between nuggets and antinuggets a similar disparity would also emerge between visible quarks and antiquarks.…”

“…The AQN model was invented long ago [21] (though a specific formation mechanism of the nuggets was developed in much more recent papers [22][23][24]) as a natural explanation of the observed ratio Ω dark ∼ Ω visible . The similarity between dark matter Ω dark and the visible matter Ω visible densities strongly suggests that both types of matter have been formed during the same cosmological epoch, which must be the QCD transition as the baryon mass m p which represents the visible portion of the matter Ω visible is obviously proportional to Λ QCD , while the contribution related to the E&W physics proportional to the quark mass ∼m q represents only a minor contribution to the proton mass.…”

“…(2) The AQN could be made of matter as well as antimatter in this framework as a result of separation of charges, see recent papers [22][23][24] with large number of technical details.…”

“…Precisely these P and CP violating processes are responsible for the separation of charges, leading to the fundamental and very generic consequence of this framework expressed as Ω dark ∼ Ω visible . The key role of the axion field at present epoch manifests itself as a substantial contribution (∼1=3) to the total nugget's mass [24].…”

“…In this model the unobserved antibaryons come to comprise the dark matter in the form of dense nuggets of quarks and antiquarks in colour superconducting (CS) phase. The formation of the nuggets made of matter and antimatter occurs through the dynamics of shrinking axion domain walls, see original papers [22][23][24] with many technical details.…”