2023-09-27 15:00  P7F Seminar Room

[Journal Club] Chiral anomaly induces superconducting baryon crystal

Dr. Geraint Evans

Determining the phase structure of nuclear and quark matter in external magnetic fields is not only of theoretical interest, but also experimentally motivated by the large magnetic fields found in heavy-ion collisions and compact star physics. I will briefly introduce my overall research on the phase structure of strongly-interacting matter at zero-temperature in large magnetic fields, then present progress and results from a recent project with the following abstract. Including the effects of the chiral anomaly within Chiral Perturbation theory, at baryon chemical potential lower than the point we expect nucleons to emerge, neutral pions form an inhomogeneous phase dubbed the Chiral Soliton Lattice 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, leading to the possibility of an inhomogeneous, superconducting charged pion phase existing above this point. Applying similar methods originally used by Abrikosov, I will present results where we have constructed such a phase in the chiral limit, demonstrating that it preferred and forms a hexagonal array of vortices. Its local effect on the baryon number density, which is non-zero and periodic like in the CSL will also be briefly discussed. I will close by showing some of our progress with calculations outside the massless pion limit.