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On the effect of resonances in the quark-photon vertex

  • Ángel S. MiramontesEmail author
  • Hèlios Sanchis-Alepuz
Open Access
Regular Article - Theoretical Physics
  • 73 Downloads

Abstract.

A calculation of hadronic timelike form factors in the Poincaré-covariant Bethe-Salpeter formalism necessitates knowing the analytic structure of the non-perturbative quark-photon vertex in the context of the Poincaré-covariant Bethe-Salpeter formalism. We include, in the interaction between quark and antiquark, the possibility of non-valence effects by introducing pions as explicit degrees of freedom. These encode the presence of intermediate resonances in the Bethe-Salpeter interaction kernel. We calculate the vertex for real as well as complex photon momentum. We show how the vertex reflects now the correct physical picture, with the rho resonance appearing as a pole in the complex momentum plane. A multiparticle branch cut for values of the photon momentum from \( -4m_{\pi}^{2}\) to \( -\infty\) develops. This calculation represents an essential step towards the calculation of timelike form factors in the Bethe-Salpeter approach.

Notes

Open Access funding provided by University of Graz.

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Copyright information

© The Author(s) 2019

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors and Affiliations

  1. 1.Institute of PhysicsUniversity of Graz, NAWI GrazGrazAustria

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