Nucleon-pion-state contribution in lattice calculations of moments of parton distribution functions

摘要

We employ chiral perturbation theory to calculate the nucleon-pion-statecontribution to the 3-point correlation functions measured in lattice QCD tocompute various moments of parton distribution functions (quark momentumfraction, helicity and transversity moment). We estimate the impact of thenucleon-pion-state contribution on the plateau method for lattice simulationswith a physical pion mass. The nucleon-pion-state contribution results in anoverestimation of all three moments. The overestimation is at the 5-20% levelfor source-sink separations of about 1.5 fm.