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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik
MP 11: Gitterfeldtheorie 1
MP 11.1: Talk
Thursday, February 28, 2013, 12:00–12:25, HS 8
Excited state systematics in extracting nucleon electromagnetic form factors from the lattice — •Thomas Rae1, Stefano Capitani1,2, Georg von Hippel1, Hartmut Wittig1,2, Benjamin Jäger1,2, Harvey Meyer1,2, Bastian Knippschild1, and Michele Della Morte1,2 — 1PRISMA Cluster of Excellence and Institut für Kernphysik, University of Mainz, Germany — 2Helmholtz Institute Mainz, University of Mainz, Germany
We present recent results for the nucleon electromagnetic form factors using lattice QCD. This includes the determination of the charge radii. The standard approach is to extract the form factors via a plateau fit to the lattice data using a ‘large-enough’ time separation between the operators at the source and sink. To check that this removes excited state contaminations to an acceptable level, we employ two further extraction methods: a fit that explicitly accounts for the contamination; and the use of a summed operator insertion, which suppresses the contamination. A comparison of the methods allows for the study of systematic effects related to excited state contributions entering in the q2 dependence of the form factors. We employ the CLS ensembles using non-perturbatively O(a) improved Wilson fermions in Nf=2 QCD.