Valence-quark distributions in the pion - art. no. 025213

We calculate the pion's valence-quark momentum-fraction probability distrib ution using a Dyson-Schwinger equation model. Valence quarks with an active mass of 0.30 GeV carry 71% of the pions momentum at a resolving scale q(0) = 0.54 GeV = 1/(0.37 fm). The shape of the calculated distribution is char acteristic of a strongly bound system and, evolved from q(0) to q = 2 GeV, it yields first, second, and third moments in agreement with lattice and ph enomenological estimates. and valence-quarks carrying 49% of the pion's mom entum. However, pointwise there is a discrepancy between our calculated dis tribution and that hitherto inferred from parametrizations of extant pion-n ucleon Drell-Yan data.