https://doi.org/10.1051/epjconf/202429613009
Far-off-equilibrium early-stage dynamics in high-energy nuclear collisions
1 Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
2 Department of Physics, The Ohio State University, Columbus, OH 43210, USA
3 Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
* e-mail: cchatto@ncsu.edu
** e-mail: heinz.9@osu.edu
*** e-mail: tmschaef@ncsu.edu
Published online: 26 June 2024
We explore the far-off-equilibrium aspects of the (1+1)-dimensional early-stage evolution of a weakly-coupled quark-gluon plasma using kinetic theory and hydrodynamics. For a large set of far-off-equilibrium initial conditions the system exhibits a peculiar phenomenon where its total equilibrium entropy decreases with time. Using a non-equilibrium definition of entropy based on Boltzmann’s H-function, we demonstrate how this apparently anomalous behavior is consistent with the second law of thermodynamics. We also use the H-function to formulate ‘maximum-entropy’ hydrodynamics, a far-offequilibrium macroscopic theory that can describe both free-streaming and nearequilibrium regimes of quark-gluon plasma in a single framework.
© The Authors, published by EDP Sciences, 2024
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
