Dv. Shirkov et Il. Solovtsov, ANALYTIC MODEL FOR THE QCD RUNNING COUPLING WITH UNIVERSAL (ALPHA)OVER-BAR(S)(0) VALUE, Physical review letters, 79(7), 1997, pp. 1209-1212
We discuss the new model expression <(alpha)over bar>(an)(Q(2)) recent
ly obtained for the QCD running coupling with a regular ghost-free beh
avior in the ''low Q(2)'' region. Being deduced from the standard ''as
ymptotic-freedom'' expression by imposing the Q(2) analyticity-without
any adjustable parameters-it has nice features: (i) The universal lim
iting value <(alpha)over bar>(an)(0) = 4 pi/beta(0) expressed only via
group symmetry factors and independent of experimental estimates on t
he running coupling <(alpha)over bar>(s)(Q(2)) (of QCD scale parameter
Lambda). This value is stable with respect to higher order correction
s. (ii) Stability of IR behavior with respect to higher-loop effects.
(iii) Coherence between the experimental <(alpha)over bar>(an)(M-r(2))
value and integral information on IR <(alpha)over bar>(s)(Q(2)) behav
ior as extracted from jet physics data.