Action principle and relativistic plasma in strong magnetic fields with Mikhail Stephanov

The dynamics of matter in strong, space-time-dependent magnetic fields is of interest in many different contexts, including nuclear fusion, neutron stars, and the quark–gluon plasma (QGP) in heavy-ion collisions. We show that a constrained action principle naturally reproduces the nontrivial equations of motion of charged particles in the guiding-center approximation. Beyond its simplicity, the advantage of this new approach is that it preserves explicit relativistic invariance and readily generalizes to curved gravitational backgrounds, thereby solving a long-standing problem. Furthermore, we derive a manifestly Lorentz-invariant kinetic theory, as well as ideal hydrodynamics, in strong magnetic fields. We argue that this formulation of guiding-center hydrodynamics remains valid even for strongly coupled plasmas, such as the QGP produced in heavy-ion collisions.

This lecture was made possible by the William C. Ferguson Fund.