3D Baryon crystal from the chiral anomaly

Geraint Evans^1,2,3*, Andreas Schmitt²

¹Institute of Physics, Academia Sinica, Taipei, Taiwan
²Mathematical Science, University of Southampton, Hampshire, UK
³Institut für Theoretische Physik, Goethe University, Frankfurt, Hesse, Germany

* Presenter:Geraint Evans, email:geraint.evans47@gmail.com

Understanding the QCD phase diagram at large magnetic fields is not only of theoretical interest, but relevant to the understanding of matter formed in heavy-ion collisions and compact star cores. Including the effects of the chiral anomaly within Chiral Perturbation Theory at finite baryon chemical potential, it has been shown that neutral pions form an inhomogeneous phase dubbed the "Chiral Soliton Lattice" (CSL) above a certain critical magnetic field. Above a second, even higher critical field, the CSL becomes unstable to fluctuations of charged pions, implying they condense.

I will point out the similarity of this second critical field to the upper critical magnetic field in conventional type-II superconductors, suggesting that an inhomogeneous superconducting charged pion phase exists beyond this point. Applying similar methods originally used by Abrikosov, I will present results where we've constructed such a phase and show the region where it is preferred in the baryon chemical potential-magnetic field phase diagram at zero temperature. This new phase has a non-zero, periodic baryon density in all three spatial dimensions.

G. W. Evans and A. Schmitt, JHEP 09, 192 (2022), arXiv:2206.01227 [hep-th]
G. W. Evans and A. Schmitt, JHEP 2024, 041 (2024), arXiv:2311.03880 [hep-th]

Keywords: QCD phase diagram, Magnetic field, Chiral perturbation theory, Pions and Baryons, Superconductivity