Three-dimensional Tomography of the Nucleon

Nucleon structure is being investigated at major experimental facilities world-wide, such as CERN and Jefferson Lab.

Understanding how nucleon properties emerge from quarks and gluons comprises one ofthe key goals of the Electron-Ion Collider (EIC) to be built at BNL.

Generalized partons distribution (GPDs) provide detailed information on the three-dimensional structure of the nucleon in impact parameter space. Recent progress in lattice Quantum Chromodynamics (QCD) is allowing the direct computation of these non-perturbative quantities starting directly from the QCD Lagrangian.

 The main aim of this proposal secure computational resources to compute GPDs using one twisted mass fermion ensemble simulated with physical values of the quark masses.

This will be the third ensemble to  bused for computing these quantities allowing, for the first time for these quantities, a continuum extrapolation.

The analysis of the other two ensembles with coarser lattice spacing and smaller lattice volume is on-going using other resources.

Both the disconnected quark loops and gluon contributions will be computed allowing for a full flavor decomposition of GPDs and parton distributions (PDFs), the forward limit of GPDs.

The project willyield results on the distribution of partons in the nucleon in the continuum limit eliminating uncontrolled systematics due to cut-off effect and chiral extrapolation.

Such results will not only have a huge impact on the interpretation of results from on-going experiments but also will provide predictions and guidance forfuture experiments.