Process-independent strong running coupling

TL;DR

This paper unifies phenomenological and computational approaches to QCD's infrared behavior, introducing a process-independent running coupling analogous to QED's effective charge, which aligns closely with the Bjorken sum rule.

Contribution

It introduces a new process-independent effective charge for QCD, bridging data-driven and continuum theory methods, enhancing understanding of strong interactions.

Findings

The new effective charge closely matches the Bjorken sum rule-based charge.

The approach provides a unified framework for QCD infrared behavior.

It offers a potential empirical method to probe QCD's effective coupling.

Abstract

We unify two widely different approaches to understanding the infrared behaviour of quantum chromodynamics (QCD), one essentially phenomenological, based on data, and the other computational, realised via quantum field equations in the continuum theory. Using the latter, we explain and calculate a process-independent running-coupling for QCD, a new type of effective charge that is an analogue of the Gell-Mann--Low effective coupling in quantum electrodynamics. The result is almost identical to the process-dependent effective charge defined via the Bjorken sum rule, which provides one of the most basic constraints on our knowledge of nucleon spin structure. This reveals the Bjorken sum to be a near direct means by which to gain empirical insight into QCD's Gell-Mann--Low effective charge.