Do current-density nonlinearities cut off the glass transition?

TL;DR

This paper investigates whether nonlinear current-density couplings in mode coupling theories genuinely cut off the ideal glass transition, concluding that such couplings are negligible near the transition and that activated processes are responsible for the transition cutoff.

Contribution

The paper challenges the assumption that current-density nonlinearities cut off the glass transition, arguing they are negligible and highlighting the role of activated processes instead.

Findings

Current-density nonlinearities are negligible near the glass transition.

Activated processes can cut off the ideal glass transition.

Memory function becomes linear due to activated processes.

Abstract

Extended mode coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular `ideal glass transition', present in the standard mode coupling theory where such couplings are ignored. We suggest here that, rather than allowing for activated processes as sometimes supposed, contributions from current-density couplings are always negligible close to a glass transition. We discuss in schematic terms how activated processes can nonetheless cut off the transition, by causing the memory function to become linear in correlators at late times.