Analytic and “frozen” coupling constants in QCD up to NNLO from DIS data

Deep inelastic scattering data on the F2 structure function provided by the BCDMS, SLAC, and NMC Collaborations are analyzed in the nonsinglet approximation with the analytic and “frozen” modifications of the strong-coupling constant featuring no unphysical singularity (the Landau pole). Improvement of agreement between theory and experiment, with respect to the case of the standard perturbative definition of αs considered recently, is observed and the higher-twist terms are shown to reduce at the next-to-next-to-leading order accuracy thus confirming earlier studies.