Neutrino emission and initial evolution of axionic quark nuggets

TL;DR

This paper investigates the early evolution of axionic quark nuggets, considering neutrino emission and bulk baryon number contributions, leading to potentially smaller objects without compromising their role as dark matter candidates.

Contribution

It introduces the possibility that bulk baryon number and neutrino emission significantly affect the initial evolution of axionic quark nuggets, refining previous models.

Findings

Objects may undergo more violent contraction and cooling.

Neutrino emission could lead to smaller nugget sizes.

Cosmological relevance of the nuggets remains intact.

Abstract

The axion quark nuggets introduced in \cite{zhitnitsky}-\cite{zhitnitsky13} are a candidate for cold dark matter which, in addition, may be relevant in baryogenesis scenarios. The present work studies their evolution till they enter in the colour superconducting phase. This evolution was already considered in \cite{zhitnitsky5}, where it is concluded that a large chemical potential $\mu$ is induced on the bulk of the object. The baryon number accumulated at the domain wall surrounding the object is taken as predominant in \cite{zhitnitsky5}, and it is suggested that internal and external fluxes are compensated and can be neglected. In the present work, the possibility that the bulk contribution to the baryon number may be relevant at initial stages and that the object may emit a large amount of neutrinos due to quark-antiquark annihilations is taken into account. The outcome is a more violent contraction of the object and, perhaps, a more effective cooling. Therefore, the resulting objects may have a smaller size. Even taking into account these corrections, it is concluded that the cosmological applications of these objects are not spoiled. These applications are discussed along the text.