Short Note on Spin Magnetization in QGP

TL;DR

This paper explores how spin magnetization of quark and lepton gases in the early Universe could generate extremely strong magnetic fields, with implications for cosmic magnetic field origins and laboratory QGP experiments.

Contribution

It presents a detailed theoretical model of spin magnetization in QGP, including calculations for multi-component fermion gases and their role in primordial magnetic field generation.

Findings

A single flavor up-quark gas could produce magnetic fields >10^{15} Tesla.

Magnetization shows 1/T scaling at high temperatures, possibly very small.

Pre-existing magnetic fields can be preserved through polarization as the Universe cools.

Abstract

We outline the theory of spin magnetization applicable to the QGP (quark-gluon plasma) epoch of the Universe. We show that a fully spin-polarized single flavor up-quark gas could generate a cosmic magnetic fields in excess of $10^{15}$ Tesla, far in excess of a possible upper limit to the primordial field. The complete multi component ferro-magnetized primordial fermion gas we consider consists of (five) nearly free electrically charged quarks, and leptons (electrons, muons, tau). We present details of how the magnetization is obtained using a grand partition function approach and point to the role of the nonrelativistic particle component. In the range of temperature 150 MeV to 500 MeV our results are also of interest to laboratory QGP experiments. We show that the required polarization capable to explain large scale structure magnetic fields observed has $1/T$ scaling in the limit of high $T$, and could be very small, at pico-scale. In the other limit, as temperature decreases in the expanding Universe, we show that any magnetic fields present before hadronization can be carried forward to below quark confinement condition temperature by polarization of electrons and muons.