hep-ph/9704333

Analytic model for the QCD running coupling with universal alpha-s (0) value

Shirkov, D.V. (Dubna, JINR) ; Solovtsov, I.L. (Dubna, JINR)

Published in: Phys.Rev.Lett.
Year: 1997
Vol.: 79
Page No: 1209-1212
Pages: 7

Abstract: We discuss the new model expression $\bar{\alpha}_{an}(Q~2)$ recently obtained for the QCD running coupling with a regular ghost-free behavior in the "low $Q~2$" region. Being deduced from the standard "asymptotic-freedom" expression by imposing the $Q~2$-analyticity -- without any adjustable parameters -- it obeys nice features: (i) The universal limiting value $\bar{\alpha}_{an}(0)=4\pi /\beta_0 \simeq 1.4$ expressed only via group symmetry factors and independent of experimental estimates on the running coupling $\bar{\alpha}_s(Q~2)$ (of QCD scale parameter $\Lambda$). This value turns out to be stable with respect to higher order corrections; (ii) Stability of IR behavior with respect to higher-loop effects; (iii) Coherence between the experimental $\bar{\alpha}_{an}(M_{\tau}~2)$ value and integral information on IR $\bar{\alpha}_s(Q~2)$ behavior as extracted from jet physics data.

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