The Lamb Shift in a Light Front Hamiltonian Approach

TL;DR

This paper demonstrates a first-principles calculation of the Lamb shift in hydrogen using light-front Hamiltonian methods, highlighting potential insights for non-perturbative QCD approaches.

Contribution

It advances light-front Hamiltonian techniques by computing the Lamb shift from fundamental QED principles and discusses implications for non-perturbative QCD.

Findings

Qualitative differences between QED and QCD analyzed

Insights into constituent picture in gauge theories

Discussion on emergence of rotational invariance

Abstract

Light-front Hamiltonian methods are being developed to attack bound-state problems in QCD. In this paper we advance the state of the art for these methods by computing the well-known Lamb shift in hydrogen starting from first principles of QED. There are obvious but significant qualitative differences between QED and QCD. In this paper, we discuss the similarities that may survive in a non-perturbative QCD calculation in the context of a precision non-perturbative QED calculation. Central to the discussion are how a constituent picture arises in a gauge field theory, how bound-state energy scales emerge to guide the renormalization procedure, and how rotational invariance emerges in a light-front calculation.