Higher-twist contribution to pion structure function: 4-Fermi operators

We present quenched lattice QCD results for the contribution of higher-twis t operators to the lowest non-trivial moment of the pion structure function . To be specific, we consider the F-2(pi+) + F-2(pi-) - 2F(2 pi)(0) which h as I = 2 and receives contributions from 4-Fermi operators only. We introdu ce the basis of lattice operators. The renormalization of the operators is done perturbatively in the MS scheme using the 't Hooft-Veltman prescriptio n for gamma(5), taking particular care of mixing effects. The contribution is found to be of O(f(pi)(2)/Q(2)), relative to the leading contribution to the moment of F-2(pi+). (C) 2000 Elsevier Science B.V. All rights reserved .