Seminarium Fizyki Materii Skondensowanej

The three-dimensional XY model describes the universal properties of Helium at its superfluid transition. The attempts to define a mass of vortices in superfluids faced, in particular, the difficulty of a divergence that is a particular case of Derrick’s theorem for classical field theories. We show that nearby the XY critical point, where fluctuations dominate and classical field theory does not apply, the vortex exists as a fundamental topological excitation with a finite mass. We exhibit perfect agreement between high precision Monte Carlo simulations and exact analytic determinations of magnetization and energy density profiles, and in the process determine the mass of the vortex excitation. Before presenting the results for the 3D-XY model this talk will expose an introductory overview of the exact theory of phase separation and interfacial phenomena and its extension to three-dimensional systems. To obtain the meeting link, contact Pawel Jakubczyk.