Diana Nicmorus

University of Graz, Austria

Baryon-photon interaction in a Dyson-Schwinger equation approach

I present a Dyson-Schwinger equation motivated study of the physics that governs the nucleon. In particular I focus on the quark-core contributions to the nucleon and delta resonance masses and their electromagnetic form factors. The calculations are performed within a Poincare-covariant Faddeev framework describing the quark-core of the nucleon via a quark-diquark picture. A consistent setup for the dressed-quark propagator, the quark-quark and the quark-diquark interactions is used, where all the ingredients are solutions of their respective Dyson-Schwinger or Bethe-Salpeter equations and obtained in the rainbow-ladder truncation. In the quark-diquark picture a baryon-photon vertex that fulfills the electromagnetic Ward-Takahashi identity is resolved by specifying the quark-photon and diquark-photon vertices, and by using a consistent ansatz for the seagull terms. I discuss the evolution of the nucleon and delta properties with the current quark mass, as well as the role of the pion cloud in this approach. I also present a comparison of the results to a collection of experimental and lattice data.

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