Alladi Ramakrishnan Hall

Formulation and applications of `maximum-entropy hydrodynamics’ in describing the far-from-equilibrium stages of heavy-ion collisions

Chandrodoy Chattopadhyay

North Carolina State University

I shall discuss far-off-equilibrium aspects of the early-stage evolution of a weakly-coupled quark-gluon plasma using hydrodynamics and kinetic theory. For a large set of far-off-equilibrium initial conditions one finds that the macroscopic evolution
appears to violate simple rules based on the second law of thermodynamics. I shall provide an in-depth microscopic understanding of this apparently anomalous macroscopic phenomenon in terms of the novel concept of `non-equilibrium cooling’ and establish its
thermodynamic consistency. I will use Boltzmann’s H-function to formulate ‘maximum-entropy hydrodynamics’, a far-off equilibrium macroscopic theory that is effective in describing both free-streaming and near-equilibrium regimes of quark-gluon plasma. Unlike
traditional hydrodynamic theories this formulation incorporates contributions to all orders in shear and bulk inverse Reynolds numbers, allowing it to handle large dissipative fluxes that characterize the early evolution stage in heavy-ion collisions. By
considering flow profiles relevant for nuclear collisions at very high energies, I will demonstrate that ‘maximum-entropy hydrodynamics’ provides excellent agreement with underlying kinetic theory throughout the fluid’s evolution, especially in
out-of-equilibrium regimes where traditional hydrodynamics breaks down.