On Infravacua and the Localisation of Sectors

TL;DR

This paper demonstrates that certain superselection sectors of a free massless scalar field, initially non-localizable, become better localized in spacelike cones when viewed against infravacuum backgrounds, modeled after infrared radiation clouds.

Contribution

It introduces a new perspective on localization of sectors in quantum field theory by using infravacuum backgrounds, extending previous models of infrared radiation.

Findings

Superselection sectors become localized in spacelike cones with infravacuum backgrounds.

Infravacuum states are modeled after infrared radiation clouds.

Enhanced localization helps understand infrared effects in quantum fields.

Abstract

A certain class of superselection sectors of the free massless scalar field in 3 space dimensions is considered. It is shown that these sectors, which cannot be localised with respect to the vacuum, acquire a much better localisation, namely in spacelike cones, when viewed in front of suitable ``infravacuum'' backgrounds. These background states coincide, essentially, with a class of states introduced by Kraus, Polley and Reents as models for clouds of infrared radiation.