Atoms in Flight and the Remarkable Connections between Atomic and Hadronic Physics

TL;DR

This paper explores the deep connections between atomic and hadronic physics through gauge theories, highlighting how techniques from one domain inform the other and offering new insights into QCD and cosmology.

Contribution

It demonstrates the analogies between atomic physics equations and hadron physics, and introduces methods for applying atomic physics techniques to QCD and cosmological problems.

Findings

Light-front equations approximate hadron spectroscopy.

Renormalization scale setting in QCD inspired by QED.

Atomic physics methods aid in understanding hadron formation.

Abstract

Atomic physics and hadron physics are both based on Yang Mills gauge theory; in fact, quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics provide important insight into the theory of hadrons in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of light-front relativistic equations of motion which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The renormalization scale for the running coupling, which is unambiguously set in QED, leads to a method for setting the renormalization scale in QCD. The production of atoms in flight provides a method for computing the formation of hadrons at the amplitude level. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, and light-front quantization have equal utility for atomic physics, especially in the relativistic domain. I also present a new perspective for understanding the contributions to the cosmological constant from QED and QCD.