The strong coupling from the IR to the UV extremes: Determination of $\alpha_s$ and prospects from EIC and JLab at 22 GeV

Abstract

We discuss how the Bjorken sum rule allows access to the QCD running coupling $\alpha_s$ at any scale, including in the deep infrared IR domain. The Bjorken sum data from Jefferson Lab, together with the world data on $\alpha_s$ reported by the Particle Data Group, allow us to determine the running of $\alpha_s(Q)$ over five orders of magnitude in four-momentum $Q$. We present two possible future measurements of the running of $\alpha_s(Q)$ using the Bjorken sum rule: the first at the EIC, covering the range $1.5 < Q < 8.7$ GeV, and the second at Jefferson Lab at 22 GeV, covering the range $1.0 < Q < 4.7$ GeV.