Next-to-Leading Order Shear Viscosity in lambda phi^4 Theory

TL;DR

This paper calculates the shear viscosity in lambda phi^4 theory at next-to-leading order, revealing sensitivity to soft physics and subleading corrections that challenge the convergence of the series.

Contribution

It provides the first detailed next-to-leading order calculation of shear viscosity in lambda phi^4 theory, highlighting the impact of soft physics on transport coefficients.

Findings

Shear viscosity formula includes subleading corrections proportional to the coupling.

The series for shear viscosity converges similarly to the pressure series.

Soft physics significantly influences the shear viscosity at NLO.

Abstract

We show that the shear viscosity of lambda phi^4 theory is sensitive at next-to-leading order to soft physics, which gives rise to subleading corrections suppressed by only a half power of the coupling, eta = [3033.54 + 1548.3 m_{th}/T] N T^3]/[ (N+2)/3 lambda^2], with m^2_th=(N+2)/72 lambda T^2. The series appears to converge about as well (or badly) as the series for the pressure.