Seminarium Fizyki Jądra Atomowego

Relativistic hydrodynamics has become a central tool for describing the collective behavior of many-body systems on many different scales — from the quark–gluon plasma to astrophysical plasmas. Traditionally, however, hydrodynamics cares only about energy, momentum, and conserved charges, while an intrinsically quantum property of matter—spin—is averaged out. Recent measurements of spin polarization of particles emitted in relativistic heavy-ion collisions challenge this separation: the produced quark–gluon plasma appears not only to flow like a nearly perfect fluid, but also to carry a sizable, dynamically generated spin polarization aligned with its vorticity.
In this talk, I will discuss how these observations motivate an extension of relativistic hydrodynamics that treats spin as an active degree of freedom. I will outline the basic ingredients of such a “spin hydrodynamics” framework, highlight its connection to underlying quantum kinetic theory, and show how it can be applied to interpret spin polarization measurements in heavy-ion collisions. I will conclude with a brief overview of open questions.