The R ratio in e+e-, the determination of α(MZ2) and a possible non-perturbative gluonic contribution

We review the determination of the QED coupling at the Z pole, which is a crucial parameter for electroweak theory. We include recent e(+)e(-) --> hadron data from Novosibirsk and Beijing to re-evaluate alpha(M-Z(2)). We find alpha(M-Z(2))(-1) = 128.973+/-0.035 or 128.934+/-0.040 according, respectively, to whether inclusive or exclusive e(+)e(-) --> hadron data are used respectively in the interval 1.4 less than or similar to root s less than or similar to 2.1 GeV. The error is mainly due to uncertainties in the data in the low-energy region,root s less than or similar to 2.5 GeV. We rind that no advantage is obtained by analytic continuation of the dispersion relation into the complex s plane. We show that the hints of structure for root s similar to 2.5 GeV may be evidence of a non-perturbative gluonic contribution to R(s).