Infrared structure beyond locality in electrodynamics

Abstract

The infrared problems of quantum electrodynamics, in contrast to ultraviolet difficulties which are of technical nature, are related to fundamental, conceptual physical questions, such as: what is a charged particle, is the particle interpretation of the electromagnetic field complete, does a vacuum state exist, or what is the quantum status of long range degrees of freedom. On the calculational level, the standard local formulations of quantum field theory have achieved procedures to deal with infinities related to long range correlations. However, the answers to the conceptual questions formulated above, based on the locality paradigm, do not seem to be fully convincing, which is confirmed by the fact that no canonical picture did emerge. This contribution briefly characterizes perspectives which open with an admission of nonlocal variables residing in infinity, or at the boundary of spacetime after compactification. Recently, this line of investigation gains popularity.