Theoretical Physics Colloquium by Prof. Saso Grozdanov, Higgs Centre for Theoretical Physics, University of Edinburgh and University of Ljubljana
This presentation was held live on April 26, 2023 as part of the theoretical physics colloquium series hosted by Prof. Igor Shovkovy at the Arizona State University. The series features high-quality interactive presentations on current advances in theoretical physics by active researchers in the field of theoretical physics.
Abstract for this presentation:
I will discuss our recent new formulation of magnetohydrodynamics (MHD) that can be used to describe the evolution of strong magnetic fields in a variety of plasmas, including in the interiors of neutron stars. The approach is based on viewing MHD as a hydrodynamic theory with a one-form global symmetry and on developing an effective field theory for the hydrodynamic modes associated with this symmetry. After discussing some general properties of one-form symmetries, why they naturally appear in the description of plasmas, and how one can use them to describe MHD, I will also briefly present how one can construct a holographic dual of MHD.
In the second part of my talk, I will move on to our most recent investigation of MHD in the context of neutron stars, and present the derivation of the most general constitutive relation for the electric field in the presence of a strong magnetic field. This constitutive relation not only reproduces the phenomena of Ohmic decay, ambipolar diffusion, and Hall drift derived in a phenomenological model by Goldreich and Reisenegger, but it also reveals new terms in the evolution of the magnetic field which cannot easily be seen from such microscopic models. Our new formulation gives predictions for novel diffusive phenomena and for the two-point correlation functions among various components of the electric and magnetic fields. I will end my talk by commenting on various future directions and open problems.