Stress-stress correlator in lambda phi^4 theory: Poles or a Cut?

TL;DR

This paper investigates the analytical structure of the stress tensor correlator in hot lambda phi^4 theory, revealing a cut along the negative imaginary axis instead of poles, impacting hydrodynamic modeling.

Contribution

It demonstrates that the stress tensor correlator in weakly coupled lambda phi^4 theory features a cut rather than poles, challenging previous assumptions about its spectral structure.

Findings

Correlator exhibits a cut along the negative imaginary axis.

Implications for second-order hydrodynamic models.

Reveals new spectral properties of stress tensor in field theory.

Abstract

We explore the analytical properties of the traceless stress tensor 2-point function at zero momentum and small frequency (relevant for shear viscosity and hydrodynamic response) in hot, weakly coupled lambda phi^4 theory. We show that, rather than one or a small number of poles, the correlator has a cut along the negative imaginary frequency axis. We briefly discuss this result's relevance for constructing 2'nd order hydrodynamic models of hot relativistic field theories.