Five-Loop Running of the QCD coupling constant

TL;DR

This paper calculates the five-loop beta function in QCD, significantly refining predictions for the strong coupling constant and Higgs boson interactions, thereby reducing theoretical uncertainties in key Standard Model parameters.

Contribution

It provides the first analytical computation of the five-loop term in the QCD beta function, enhancing precision in theoretical predictions.

Findings

Reduced uncertainty in alpha_s at the Z-boson scale.

Improved predictions for Higgs decay rates to quarks.

Enhanced accuracy in Standard Model coupling constants.

Abstract

We analytically compute the five-loop term in the beta function which governs the running of $\alpha_s$ --- the quark-gluon coupling constant in QCD. The new term leads to a reduction of the theory uncertainty in $\alpha_s$ taken at the Z-boson scale as extracted from the $\tau$-lepton decays as well as to new, improved by one more order of perturbation theory, predictions for the effective coupling constants of the Standard Model Higgs boson to gluons and for its total decay rate to the quark-antiquark pairs.