Massless QFT and the Newton-Wigner Operator

TL;DR

This paper explicitly constructs the Newton-Wigner-Pryce operator for massless scalar fields and studies its transformation properties under the conformal group to understand particle localization.

Contribution

It provides the first explicit second-quantized form of the Newton-Wigner-Pryce operator for massless fields and analyzes its conformal covariance.

Findings

Explicit form of the Newton-Wigner-Pryce operator for massless scalar fields

Transformation behavior under the conformal group

Insights into particle localization and covariance

Abstract

In this work, the second-quantized version of the spatial-coordinate operator, known as the Newton-Wigner-Pryce operator, is explicitly given w.r.t. the massless scalar field. Moreover, transformations of the conformal group are calculated on eigenfunctions of this operator in order to investigate the covariance group w.r.t. probability amplitudes of localizing particles.