Bonn 2020 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 57: Heavy-Ion Collisions and QCD Phases XIII

HK 57.3: Talk

Friday, April 3, 2020, 11:45–12:00, J-HS G

Dynamic critical exponents from classical-statistical spectral functions — •Dominik Schweitzer¹, Sören Schlichting², and Lorenz von Smekal¹ — ¹Institut für Theoretische Physik, Justus-Liebig-Universität Gießen — ²Fakultät für Physik, Universität Bielefeld

When a thermodynamic system comes close to a critical point, large fluctuations lead to scale-invariant physics, not only in static but also dynamic observables, such as spectral functions. Such observables can be measured by a range of experiments, and will become relevant in future heavy-ion collision experiments closing in on the QCD critical point.

We investigate the dynamic critical behavior of self-interacting scalar fields with Z₂ symmetry and hence the same static universal behavior as QCD at the critical endpoint. We calculate spectral functions of the order parameter at zero and non-vanishing momenta from classical statistical lattice simulations in real time. In the high-temperature phase, we find that the spectral functions are well described by relativistic quasi-particle peaks; at low temperatures, we find an additional mode with a different dispersion relation. Close to the transition temperature, we see a strong IR contribution building up.

Considering the equations of motion for a closed system as well as a system coupled to a heat bath, we determine the underlying universal scaling functions in the critical region, and extract the dynamic critical exponents z for two different dynamic universality classes, Model A & C.