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arXiv · 1011.0170

A relativistic coupled-channel formalism for electromagnetic form factors of 2-body bound states

Elmar P. Biernat·William H. Klink·Wolfgang Schweiger
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Abstract

We discuss a Poincar\'e invariant coupled-channel formalism which is based on the point-form of relativistic quantum mechanics. Electromagnetic scattering of an electron by a 2-body bound state is treated as a 2-channel problem for a Bakamjian-Thomas-type mass operator. In this way retardation effects in the photon-exchange interaction are fully taken into account. The electromagnetic current of the 2-body bound state is then extracted from the one-photon-exchange optical potential. As an application we calculate electromagnetic pion and deuteron form factors. Wrong cluster properties, inherent in the Bakamjian-Thomas framework, are seen to cause spurious (unphysical) contributions in the current. These are separated and eliminated in an unambiguous way such that one is left with a current that has all the desired properties.

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Elmar P. Biernat, William H. Klink, Wolfgang Schweiger. 2010-10-31. A relativistic coupled-channel formalism for electromagnetic form factors of 2-body bound states. https://doi.org/10.1007/s00601-010-0180-y

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