Gradient flow for parton distribution functions: first application to the pion
Anthony Francis, Patrick Fritzsch, Robert V. Harlander, Rohith Karur, Jangho Kim, Jonas T. Kohnen, Giovanni Pederiva, Dimitra A. Pefkou, Antonio Rago, Andrea Shindler, André Walker-Loud, Savvas Zafeiropoulos
公開日: 2025/9/2
Abstract
Parton distribution functions (PDFs) are central to precision QCD phenomenology. Their Mellin moments can be computed on the lattice, but direct determinations using local operators, besides $\langle x \rangle$, face severe challenges from reduced hypercubic symmetry, limiting results to the lowest moments. A recently proposed method resolves these issues using gradient flow. We demonstrate the efficacy of this method by computing ratios of flavor non-singlet pion PDF moments up to $\langle x^5 \rangle$, on four lattice spacings at $m_\pi \simeq 411$ MeV. The moments and reconstructed PDF agree quantitatively with recent phenomenological extractions.