Münster 2002 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 9: Poster Session: Theory
HK 9.24: Poster
Tuesday, March 12, 2002, 10:30–12:45, Foyer Chemie
Quark Loop Calculations of Electroweak Meson Observables in a Covariant Bethe–Salpeter Model — •Matthias Koll, Ralf Ricken, Bernard Metsch, and Vladimir Hellmann — Institut für Theoretische Kernphysik, Nußallee 14-16, D–53115 Bonn, Germany
We present recent theoretical results concerning electroweak processes such as γγ decays of π0,η,η′ mesons, the so–called π2ℓγ/K2ℓγ decays or scattering reactions like γπ→γπ and related processes. The basis of our calculations is a relativistic quark model based on the instantanteous Bethe–Salpeter equation; as quark–antiquark interactions, we adopt a linearly rising confinement potential with a suitably chosen spinorial structure plus a residual force induced by ’t Hooft’s instantons.
First, we present the results for the light meson spectrum where we ultimately fix the few parameters of our model. We then discuss certain decays of pseudoscalar mesons into non–hadronic final states and compare the results with experimental data as well as with other theoretical calculations. Finally, we study the relevance of pure quark box contributions to processes like γγ→ππ or Compton scattering off pseudoscalar mesons at low energies and present our lowest order results concerning specific scattering reactions.