# The shear and bulk relaxation times from the general correlation functions

## TL;DR

This paper derives Kubo formulas for shear and bulk relaxation times and computes the shear viscosity relaxation time in massless bb theory using a diagrammatic approach, advancing understanding of quantum field relaxation processes.

## Contribution

It introduces new Kubo formulas for relaxation times and provides the first diagrammatic calculation of shear viscosity relaxation time in massless bb theory.

## Key findings

- Kubo formulas for shear and bulk relaxation times derived
- Shear viscosity relaxation time calculated in massless bb theory
- Results enhance understanding of quantum field relaxation dynamics

## Abstract

In this paper we present two quantum field theoretical analyses on the shear and bulk relaxation times. First, we discuss how to find Kubo formulas for the shear and the bulk relaxation times. Next, we provide results on the shear viscosity relaxation time obtained within the diagrammatic approach for the massless $\lambda\phi^4$ theory.