New extraction of alphas(MZ) from proton DIS data
Abstract
An exploratory study for a new determination of the strong coupling constant alphas(MZ) from existing world data on the proton structure function F2p in the Q**2-range from ~ 5 to ~ 120 (GeV/c)**2 is presented. The main features of our approach are: 1) the use of low-order Nachtmann moments evaluated with a direct contribution from data larger than 70% of the total; 2) the inclusion of high-order perturbative effects through the soft gluon resummation technique; 3) a direct control over higher-twist effects; and 4) the independence from any specific choice of the x-shape of the input parton distributions. At next-to-leading order we get alphas(MZ) = 0.1209 +/- 0.0010 (stat.) +/- 0.0015 (syst.) with a significant dependence upon the order of the moment used. Including soft gluon effects we obtain alphas(MZ) = 0.1188 +/- 0.0010 (stat.) +/- 0.0014 (syst.) with a remarkable better stability against the order of the moment. Our findings are compared with recent DIS determinations of alphas(MZ) and directions for future improvements are discussed.
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