Perturbative renormalization of proton observables in lattice QCD using domain wall fermions

Abstract

Deep inelastic scattering unambiguously measures hadron observables characterizing the quark-gluon structure of hadrons. The only way to calculate these observables from first principles is lattice QCD. Experiments measure matrix elements of light cone operators ... where diagonal elements specify the quark density distribution q(x), quark helicity distribution [delta] q(x) and quark transversity distribution [delta] q(x). Off-diagonal elements determine form factors and general parton distributions. Due to the Minkowskian nature of these matrix elements, they cannot be evaluated on a Euclidean lattice so one uses the operator product expansion to calculate matrix elements ... which specify moments of these distributions. In this thesis, renormalization factors have been calculated for local bilinear operators of the form ... in a given irreducible representation of hypercubic group as well as mixing coefficients of those operators for low moments of physical interest. In the past, it was only possible to calculate with quark masses such that ... Now for the first time using Ginsparg-Wilson "Domain Wall" fermions with HYP smearing and full QCD configurations on large lattices make calculations possible in the physical chiral regime.