QCD coupling constant at next-to-next-to-leading order from DIS data

Deep inelastic scattering data on F2 structure function from various fixed-target experiments were analyzed in the nonsinglet approximation with a next-to-next-to-leading-order accuracy. The study of high statistics deep inelastic scattering data provided by BCDMS, SLAC, NMC, and BFP Collaborations was carried out separately for the first one and the rest, followed by a combined analysis done as well. For the coupling constant the following value αs(MZ2)=0.1167±0.0021(total exp error)+((+0.0056/-0.0036)(theor) was found, which in this approximation turns out to be slightly less than that obtained at the next-to-leading order, as was generally anticipated. Ditto the theoretical uncertainties reduced with respect to those obtained in the case of the next-to-leading-order analysis, thus confirming earlier observations.