On Infravacua and Superselection Theory

TL;DR

This paper extends superselection sector analysis to infravacuum states in models with massless particles, showing that their superselection structure and spectra are similar to vacuum states, supporting infravacua as a natural framework.

Contribution

It introduces a novel approach to analyze superselection sectors relative to infravacua, demonstrating their structural similarity to vacuum states in theories with long-range forces.

Findings

Superselection structure is unchanged in infravacua.

Energy-momentum spectrum matches that of vacuum states.

New method relates spectrum shape to local charge transfer cocycles.

Abstract

In the DHR theory of superselection sectors, one usually considers states which are local excitations of some vacuum state. Here, we extend this analysis to local excitations of a class of "infravacuum" states appearing in models with massless particles. We show that the corresponding superselection structure, the statistics of superselection sectors and the energy-momentum spectrum are the same as with respect to the vacuum state. (The latter result is obtained with a novel method of expressing the shape of the spectrum in terms of properties of local charge transfer cocycles.) These findings provide evidence to the effect that infravacua are a natural starting point for the analysis of the superselection structure in theories with long-range forces.