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HK: Fachverband Physik der Hadronen und Kerne

HK 38: Heavy-Ion Collisions and QCD Phases VIII

HK 38.1: Vortrag

Mittwoch, 22. März 2023, 15:45–16:00, SCH/A315

Critical dynamics in the real-time functional renormalization group — •Johannes Roth¹, Leon Sieke¹, and Lorenz von Smekal^1,2 — ¹Institut für Theoretische Physik, Justus-Liebig-Universität, 35392 Giessen, Germany — ²Helmholtz Research Academy Hesse for FAIR (HFHF), Campus Giessen, 35392 Giessen, Germany

Real-time quantities such as spectral functions and transport coefficients can serve to examine the real-time evolution of a system close to equilibrium, as they encode the possible excitations in the medium and show universal static and dynamic scaling behavior near a critical point. The functional renormalization group (FRG) formulated on the Schwinger-Keldysh closed-time path provides an excellent calculational tool for such real-time correlations [1]. In this talk I will present a novel approach for the systematic construction of causal regulators for the FRG, which comply with the analytic structure of the propagators, and demonstrate that they can be interpreted as a coupling to a fictitious external heat bath with FRG scale dependent spectral distribution. As particular applications, I will discuss the relaxational Models A, B, and C according to the classification scheme by Halperin and Hohenberg, and show how they can be implemented in the real-time FRG. With this setup, I will then present results which demonstrate the generation of dynamic scaling behavior in spectral functions obtained from one and two-loop self-consistent truncation schemes.

[1] J. V. Roth, D. Schweitzer, L. J. Sieke, L. von Smekal, Phys. Rev. D 105 (2022) 116017.