https://doi.org/10.1140/epjs/s11734-025-01625-9
Regular Article
Short note on spin magnetization in QGP
Department of Physics, The University of Arizona, 85721, Tucson, AZ, USA
Received:
5
February
2025
Accepted:
4
April
2025
Published online:
11
April
2025
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 
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 non-relativistic particle component. In the range of temperature 
–
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.
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Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
