Universal amplitudes ratios for critical aging via functional renormalization group

TL;DR

This paper extends the functional renormalization group method to compute universal amplitude ratios in non-equilibrium critical phenomena, specifically analyzing the Ising model's critical relaxation and validating results against existing methods.

Contribution

It introduces a novel application of the functional renormalization group to calculate universal amplitude ratios in aging dynamics at criticality.

Findings

Predicted universal amplitude ratios agree with previous RG calculations.

Results are consistent with Monte Carlo simulations.

Method extends RG applicability to non-equilibrium critical dynamics.

Abstract

We discuss how to calculate non-equilibrium universal amplitude ratios in the functional renormalization group approach, extending its applicability. In particular, we focus on the critical relaxation of the Ising model with non-conserved dynamics (model A) and calculate the universal amplitude ratio associated with the fluctuation-dissipation ratio of the order parameter, considering a critical quench from a high-temperature initial condition. Our predictions turn out to be in good agreement with previous perturbative renormalization-group calculations and Monte Carlo simulations.