Lattice QCD Calculation of Nucleon Structure

A program to study nucleon structure and hadron spectroscopy in QCD is proposed. We would like to undertake the task of computing quark propagators of the overlap fermion which has exact lattice chiral symmetry on the dynamical fermion gauge configurations from the 2+1-flavor domain-wall fermion (DWF) action which are generated by the Riken-Brookhaven-Columbia (RBC) collaboration and the UKQCD collaboration of the United Kingdom. Since both the valence and the realistic 2+1 flavor sea quarks are based on chiral fermion formalism with both the valence and the sea quark masses close to those in nature (there are three spacings and two lattice volumes so far) these propagators would represent state-of-the-art resources for us and the world lattice community to calculate physical observables with high precision to check with experiments, to make predictions for future experiments and phenomenology, and to study chiral behavior of hadrons to confront chiral perturbation theory in this mixed chiral action approach which invokes only one extra low-energy constant. The overlap quark propagator will be calculated with deflation of low eigenmodes of the overlap fermion which speeds up the inversion by a factor of 51 to 79 with overhead which is amortized with multiple quark sources. We propose to concentrate our studies on nucleon structure. The nucleon structure study includes both the connected and disconnected insertions, namely the valence and the sea quarks, which will be calculated for both the quark and glue momenta and angular momenta as well as the quark spin so that a complete picture of the composition of the proton spin can be obtained and compared to experiments. Other nucleon form factor calculations include the strangeness magnetic and electric form factors, strangeness and charmness content, and their contributions to the quark spin and nucleon momentum. We also will calculate the components of the nucleon which include the quark energy and mass contributions, the glue energy, and the trace anomaly contributions. We aim to carry out these calculations with chiral and continuum extrapolations for lattices with 3 lattices spacings and a total of 8 sea quark masses.