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Phys. Rev. Lett. 95, 172503 (2005) [4 pages]

Δ Resonance Contribution to Two-Photon Exchange in Electron-Proton Scattering

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S. Kondratyuk and P. G. Blunden
Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2

W. Melnitchouk
Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA

J. A. Tjon
Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA
Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA

Received 9 June 2005; revised 11 October 2005; published 20 October 2005

We calculate the effects on the elastic electron-proton scattering cross section of the two-photon exchange contribution with an intermediate Δ resonance. The Δ two-photon exchange contribution is found to be smaller in magnitude than the previously evaluated nucleon contribution, with an opposite sign at backward scattering angles. The sum of the nucleon and Δ two-photon exchange corrections has an angular dependence compatible with both the polarization-transfer and the Rosenbluth methods of measuring the nucleon electromagnetic form factors.


©2005 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevLett.95.172503
DOI: 10.1103/PhysRevLett.95.172503
PACS: 25.30.Bf, 12.20.Ds, 13.40.Gp, 14.20.Gk

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