Finite-Volume Form Factors in Semiclassical Approximation

TL;DR

This paper develops a semiclassical method to compute Lorentz covariant form factors between kink states in quantum field theories with degenerate vacua, applicable to finite volume scenarios and demonstrated on Sine-Gordon and 4 theories.

Contribution

It introduces a novel semiclassical approach for calculating finite-volume form factors between kink states in 1+1 dimensional quantum field theories.

Findings

Provides explicit Lorentz covariant form factors for kink states.

Estimates spectral representations of correlation functions in finite volume.

Demonstrates applicability with Sine-Gordon and 4 models.

Abstract

A semiclassical approach is used to obtain Lorentz covariant expressions for the form factors between the kink states of a quantum field theory with degenerate vacua. Implemented on a cylinder geometry it provides an estimate of the spectral representation of correlation functions in a finite volume. Illustrative examples of the applicability of the method are provided by the Sine-Gordon and the broken \phi^4 theories in 1+1 dimensions.