Behavior of the effective QCD coupling α _τ(s) at low scales

Summary, in English

The hadronic decays of the τ lepton can be used to determine the effective charge ατ(m _τ ²,) for a hypothetical τ lepton with a mass in the range 0<m _τ,<mτ. This definition provides a fundamental definition of the QCD coupling at low mass scales. We study the behavior of α _τ at low mass scales directly from first principles and without any renormalization-scheme dependence by looking at the experimental data from the OPAL Collaboration. The results are consistent with the freezing of the physical coupling at mass scales s = m _τ ², of order 1 GeV ² with a magnitude α _τ ∼0.9 ±0.1.

• Author: Stanley J. Brodsky; Sven Menke; Carlos Merino; Johan Rathsman
• Publishing year: 2003-12-01
• Language: English
• Publication/Series: Physical Review D
• Volume: 67
• Issue: 5
• Links: http://dx.doi.org/10.1103/PhysRevD.67.055008
• Document type: Journal article
• Publisher: American Physical Society
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 0556-2821