Moments of nucleon generalized parton distributions from lattice QCD simulations at physical pion mass

• Published in: arXiv.org
• Main Authors: Alexandrou, C, Bacchio, S, Constantinou, M, Dimopoulos, P, Finkenrath, J, Frezzotti, R, Hadjiyiannakou, K, Jansen, K, Kostrzewa, B, Koutsou, G, Lauer, C, Urbach, C
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 02.03.2020
• Subjects: Axial stress; Charm (particle physics); Computation; Computer simulation; Distribution functions; Fermions; Form factors; Helicity; Momentum transfer; Nucleons; Partons; Physics - High Energy Physics - Experiment; Physics - High Energy Physics - Lattice; Physics - High Energy Physics - Phenomenology; Physics - Nuclear Theory; Pions; Quantum chromodynamics; Quarks; Tensors
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1908.10706

We present results for the moments of nucleon isovector vector and axial generalised parton distribution functions computed within lattice QCD. Three ensembles of maximally twisted mass clover-improved fermions simulated with a physical value of the pion mass are analyzed. Two of these ensembles are generated using two degenerate light quarks. A third ensemble is used having, in addition to the light quarks, strange and charm quarks in the sea. A careful analysis of the convergence to the ground state is carried out that is shown to be essential for extracting the correct nucleon matrix elements. This allows a controlled determination of the unpolarised, helicity and tensor second Mellin moments. The vector and axial-vector generalised form factors are also computed as a function of the momentum transfer square up to about 1 GeV\(^2\). The three ensembles allow us to check for unquenching effects and to assess lattice finite volume effects.