Particle Weights and their Disintegration I

TL;DR

This paper develops a framework within Local Quantum Physics to define and analyze particle weights, addressing the infraparticle problem caused by Lorentz symmetry breaking in theories with long-range interactions.

Contribution

It introduces a detailed definition and properties of particle weights, providing a unified approach to particles and infraparticles in quantum field theory.

Findings

Existence of temporal limits of physical states established.

Particle weights characterized by seminorms.

Framework applicable to theories with broken Lorentz symmetry.

Abstract

The notion of Wigner particles is attached to irreducible unitary representations of the Poincare group, characterized by parameters m and s of mass and spin, respectively. However, the Lorentz symmetry is broken in theories with long-range interactions, rendering this approach inapplicable (infraparticle problem). A unified treatment of both particles and infraparticles via the concept of particle weights can be given within the framework of Local Quantum Physics. They arise as temporal limits of physical states in the vacuum sector and describe the asymptotic particle content. In this paper their definition and characteristic properties are worked out in detail. The existence of the temporal limits is established by use of suitably defined seminorms which are also essential in proving the characteristic features of particle weights.