F_2 Structure Function and Higher-twist Contributons (Nonsinglet Case)

We performed the combine fits of SLAC, BCDMS and NMC data at NLO level. The data are fitted very well with different parametrizations of higher twist contributions. The theory-based parametrizations lead to the low values of QCD parameter \Lambda^{f=4}_{\overfull{MS}} \sim 140 \pm 21 MeV (or \alpha_s(M^2_Z)= 0.103 \pm 0.002).