Dirac and Pauli form factors from lattice QCD

Collins, S.; Horsley, R.; Winter, F.; Pleiter, D.; Zanotti, J.M.; Rakow, P.E.L.; Nobile, A.; Stüben, H.; Nakamura, Y.; Göckeler, M.; Schierholz, G.; Hägler, Ph.; Schroers, W.; Schäfer, A.

doi:10.1103/PhysRevD.84.074507

Journal Article

Dirac and Pauli form factors from lattice QCD

Collins, S. ; Göckeler, M.FZJ* ; Hägler, P. ; Horsley, R. ; Nakamura, Y. ; Nobile, A. ; Pleiter, D.FZJ* ; Rakow, P. E. L. ; Schäfer, A. ; Schierholz, G. ; Schroers, W. ; Stüben, H. ; Winter, F. ; Zanotti, J. M.

2011
Soc. [S.l.]

Physical review / D 84(7), 074507 (2011) [10.1103/PhysRevD.84.074507]

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Please use a persistent id in citations: http://hdl.handle.net/2128/11139 doi:10.1103/PhysRevD.84.074507

Abstract: We present a comprehensive analysis of the electromagnetic form factors of the nucleon from a lattice simulation with two flavors of dynamical O(a)-improved Wilson fermions. A key feature of our calculation is that we make use of an extensive ensemble of lattice gauge field configurations with four different lattice spacings, multiple volumes, and pion masses down to m(pi) similar to 180 MeV. We find that by employing Kelly-inspired parametrizations for the Q(2) dependence of the form factors, we are able to obtain stable fits over our complete ensemble. Dirac and Pauli radii and the anomalous magnetic moments of the nucleon are extracted and results at light quark masses provide evidence for chiral nonanalytic behavior in these fundamental observables.

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Note: The numerical calculations have been performed on the APEmille, apeNEXT systems and PAX cluster at NIC/DESY (Zeuthen), the IBM BlueGene/L at EPCC (Edinburgh), the IBM BlueGene/P at NIC/JSC (Julich), the QPACE systems of the SFB TR-55, the SGI Altix and ICE systems at LRZ (Munich) and HLRN (Berlin/Hannover). This work was supported in part by the DFG (SFB TR-55) and by the European Union (grants 238353, ITN STRONGnet and 227431, HadronPhysics2, and 256594). S. C. acknowledges support from the Claussen-Simon-Foundation (Stifterband fur die Deutsche Wissenschaft). P. H. acknowledges support by the Heisenberg-programme of the DFG and would like to thank the DESY Theory Group for hospitality while this work was being completed. W. S. wishes to thank J.-W. Chen at National Taiwan University and H.-Y. Cheng and H.-N. Li at Academia Sinica for their hospitality and for valuable physics discussions and suggestions. J. Z. is supported by the STFC under Grant No. ST/F009658/1.

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