CNF Seminar: Martha Constantinou

The Center for Nuclear Femtography would like to announce the inaugural session of our seminar series with a seminar given by Martha Constantinou.

Title: New methods to access GPDs from lattice QCD and synergies for nucleon tomography

Abstract: Traditionally, lattice QCD computations of GPDs have been carried out in a frame where the transferred momentum is symmetrically distributed between the incoming and outgoing hadrons. However, such frames are inconvenient for lattice QCD calculations since each value of the momentum transfer requires a separate calculation, increasing the computational cost. In recent work (PRD 106 (2022) 11, 114512), we lay the foundation for more effective calculations of GPDs applicable for any frame, with freedom in the transferred momentum distribution. An important aspect of the approach is the Lorentz covariant parameterization of the matrix elements in terms of Lorentz-invariant amplitudes, which allows one to relate matrix elements in different frames. We demonstrate the efficacy of the formalism through numerical calculations using one ensemble of Nf=2+1+1 twisted mass fermions with a pion mass of about 260 MeV. Concentrating on the proton and zero skewness, we extract the invariant amplitudes from matrix element calculations in both the symmetric and asymmetric frame and obtain results for the twist-2 light-cone GPDs for unpolarized quarks, H and E.

We discuss the necessity of lattice QCD calculation of GPDs in the pre-EIC era. Also, we address and complementarity to the theoretical and phenomenological communities within the scientific program of the DOE-funded QGT Topical Collaboration on the 3D quark and gluon tomography.