Alexandrou Constantia, Cichy Krzysztof, Constantinou Martha, Hadjiyiannakou Kyriakos, Jansen Karl, Scapellato Aurora, Steffens Fernanda
Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Kavafi Street, Nicosia 2121, Cyprus.
Phys Rev Lett. 2020 Dec 31;125(26):262001. doi: 10.1103/PhysRevLett.125.262001.
We present the first calculation of the x dependence of the proton generalized parton distributions (GPDs) within lattice QCD. Results are obtained for the isovector unpolarized and helicity GPDs. We compute the appropriate matrix elements of fast-moving protons coupled to nonlocal operators containing a Wilson line. We present results for proton momenta 0.83,1.25,1.67 GeV, and momentum transfer squared 0.69,1.38 GeV^{2}. These combinations include cases with zero and nonzero skewness. The calculation is performed using one ensemble of two degenerate mass light quarks, a strange quark, and a charm quark of maximally twisted mass fermions with a clover term. The lattice results are matched to the light-cone GPDs using one-loop perturbation theory within the framework of large momentum effective theory. The final GPDs are given in the MS[over ¯] scheme at a scale of 2 GeV.
