Mainz 2022 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 32: Hadron Structure and Spectroscopy VI

HK 32.4: Vortrag

Dienstag, 29. März 2022, 17:00–17:15, HK-H9

Electromagnetic form factors of the nucleon in N_f = 2 + 1 lattice QCD — Dalibor Djukanovic^1,2, Georg von Hippel³, Harvey B. Meyer^1,2,3, Konstantin Ottnad³, •Miguel Salg³, Jonas Wilhelm³, and Hartmut Wittig^1,2,3 — ¹Helmholtz Institute Mainz, Staudingerweg 18, 55128 Mainz, Germany — ²GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany — ³PRISMA⁺ Cluster of Excellence and Institute for Nuclear Physics, Johannes Gutenberg University of Mainz, Johann-Joachim-Becher-Weg 45, 55128 Mainz, Germany

We present results for the electromagnetic form factors of the nucleon computed on the Coordinated Lattice Simulations (CLS) ensembles with N_f = 2 + 1 flavors of O(a)-improved Wilson fermions and an O(a)-improved conserved vector current. From the Q²-dependence of the form factors, we determine the electric and magnetic charge radii and the magnetic moment of the proton. In order to estimate the excited-state contamination, we employ several source-sink separations and apply the summation method. The quark-disconnected diagrams entering into the isoscalar quantities are computed explicitly. For this purpose, a stochastic estimation based on the one-end trick is performed, in combination with a frequency-splitting technique and the hopping parameter expansion. By these means, we obtain a clear signal for the form factors including the quark-disconnected contributions, which have a statistically significant effect on our results.