Köln 2004 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 6: Theory II
HK 6.2: Gruppenbericht
Montag, 8. März 2004, 16:15–16:45, E
Point-Form Dynamics of Relativistic Few-Body Sytems — •Wolfgang Schweiger1, Marcus Lechner1, William H. Klink2, and Andreas Krassnigg3 — 1Inst. Theor. Physik, Univ. Graz, Graz, Austria — 2Dept. Physics and Astr., Univ. of Iowa, Iowa City, USA — 3Argonne National Lab., Argonne, USA
The general problem of formulating relativistic quantum mechanics for a fixed number of particles goes back to the pioneering work of Dirac in which he suggested three different forms of relativistic dynamics, i.e. the instant form, the front form, and the point form. These forms differ by the set of Poincarè generators which are interaction dependent. Although it has a number of advantages, the point form has been the least used and is the most unfamiliar of the three forms. Our contribution deals with a point-form formulation of relativistic few-body systems. We present a relativistic, Poincarè invariant coupled-channel formalism for few-body systems interacting via one-particle exchange. Our approach takes the exchange particle explicitly into account and relates the coupling of the exchange particle to an underlying quantum field theory. As illustrative examples we will present vector mesons within the chiral constituent quark model and electromagnetically bound systems like hydrogen and positronium. The vector-meson system allows us to study the effect of retardation in the Goldstone-boson exchange. The investigation of hydrogen and positronium serves as a test of the point-form approach for well studied QED systems and reveals the relation between point-form and instant-form dynamics.