On the Behavior of the Effective QCD Coupling {alpha}{sub {tau}}(s)at Low Scales

Technical Report · Wed Dec 11 04:00:00 EST 2002

DOI:https://doi.org/10.2172/808702· OSTI ID:808702

Brodsky, Stanley J ^[1]

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1. SLAC

The hadronic decays of the {tau} lepton can be used to determine the effective charge {alpha}{tau}(m{sub {tau}{prime}}{sup 2}) for a hypothetical {tau}-lepton with mass in the range 0 < m{sub {tau}{prime}} < m{sub {tau}}. This definition provides a fundamental definition of the QCD coupling at low mass scales. We study the behavior of {alpha}{sub {tau}} 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{sub {tau}{prime}}{sup 2} of order 1 GeV{sup 2} with a magnitude {alpha}{sub {tau}} {approx} 0.9 {+-} 0.1.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (US)
• Sponsoring Organization: USDOE Office of Science (US)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 808702
• Report Number(s): SLAC-PUB-9559
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
EFFECTIVE CHARGE
FREEZING
LEPTONS
OPALS
QUANTUM CHROMODYNAMICS