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DY: Fachverband Dynamik und Statistische Physik

DY 12: Statistical Physics far from Thermal Equilibrium II

DY 12.1: Talk

Monday, March 18, 2024, 15:00–15:15, BH-N 334

Dynamic renormalization of active field theories — •Nikos Papanikolaou and Thomas Speck — Institute of Theoretical Physics 4, University of Stuttgart, Stuttgart, Germany

Conservative scalar field theories function as coarse-grained models that describe systems with conserved dynamics featuring a single order parameter, such as density, magnetization, or height. Notable examples include Model B (for liquid-gas separation), cKPZ (for surface growth with conserved dynamics), and Active Model B+ (AMB+) (for self-propelled particles with density-dependent speed). Dynamical renormalization is a powerful tool to study the critical behavior of these theories and to determine the relevant parameters dictating their large-scale dynamics. Here, we apply this technique to AMB+, a recent generalization of Model B involving non-potential terms. Analyzing such complex field theories poses a challenge due to its cumbersome calculations. To facilitate the analysis, we developed a symbolic computer algebra code to obtain the graphical corrections of the model parameters. Applying this framework to AMB+, we find that potentially relevant higher-order non-linear terms are generated, limiting the regime of the perturbative renormalization. We explore strategies to ameliorate this problem and provide evidence that no perturbative fixed points other than the Wilson-Fisher fixed point exist.

Keywords: renormalization group; phase transitions; active matter; scalar field theories; statistical physics