Electric and magnetic axion quark nuggets, their stability and their detection

TL;DR

This paper explores the theoretical implications of ferromagnetism in axion quark nuggets, focusing on their stability, electromagnetic interactions, and potential role as dark matter, with emphasis on pair production and magnetic field decay.

Contribution

It introduces the possibility of ferromagnetic behavior in axion quark nuggets and analyzes the resulting electromagnetic effects and stability considerations.

Findings

Critical magnetic field value for nugget stability identified

Large pair production possible near the critical magnetic field

Magnetized nuggets could contribute to dark matter if magnetic fields decay

Abstract

The present work studies the dynamics of axion quark nuggets introduced in \cite{zhitnitsky} and exploited in the works \cite{zhitnitsky2}-\cite{zhitnitsky13}. The new feature considered here is the possibility that these nuggets become ferromagnetic. This possibility was pointed out in \cite{tatsumi}, although ferromagnetism may also take place due some anomaly terms found in \cite{son}-\cite{son2}. The purpose of the present letter however, is not to give evidence in favor or against these statements. Instead, it is focused in some direct consequences of this ferromagnetic behavior, if it exists. The first is that the nugget magnetic field induces an electric field due to the axion wall, which may induce pair production by Schwinger effect. Depending on the value of the magnetic field, the pair production can be quite large. A critical value for such magnetic field at the surface of the nugget is obtained, and it is argued that the value of the magnetic field of \cite{tatsumi} is at the verge of stability and may induce large pair production. The consequences of this enhanced pair production may be unclear. It may indicate that the the nugget evaporates, but on the other hand it may be just an indication that the intrinsic magnetic field disappears and the nuggets evolves to a non magnetized state such as \cite{zhitnitsky}-\cite{zhitnitsky13}. The interaction of such magnetic and electric nugget with the troposphere of the earth is also analyzed. However, if the magnetic field does not decay before the actual universe, then this would lead to high energy electron flux due to its interaction with the electron gases of the Milky Way. This suggests that these magnetized quarks may be a considerably part of dark matter, but only if their hypothetical magnetic and electric fields are evaporated.