Relativistic Quark-Model Description of Low-Energy Baryons

Willibald PLESSAS

(Uni. Graz, Austria)

Sala 2.8.3, IST, Dept. de FĂ­sica
Wednesday, November 4th, 2015 at 02:30 PM


he notion of (constituent/valence) quarks has been introduced more than fifty years ago. Quantum chromodynamics (QCD) was invented more than forty years ago, and it has not yet been amenable to a satisfactory solution up till now. The more there is the need for an effective description of hadrons at low and intermediate energies in view of the wealth of phenomenological data accumulated over the past decades. I discuss the present performance of a modern constituent-quark model as an effective tool for the description of baryons in the non-perturbative regime of QCD. In particular, I address a relativistic constituent-quark model capable of describing all known baryons with flavors u, d, s, c, and b universally in a single framework. Hereby baryons are considered as systems of three relativistic constituent quarks, whose flavor-dependent interactions are based on the exchange of Goldstone bosons within SU(5)_F and implemented into a Poincaré-invariant interacting mass operator. Predictions for the spectroscopy of baryons containing all flavors u, d, s, c, and b compare well with the existing phenomenology and with modern results available from lattice QCD. Similarly the structures of baryons as revealed under electromagnetic, weak, hadronic, and gravitational interactions are consistently described. Covariant results so far obtained for electromagnetic, axial, strong, and gravitational form factors of the nucleons, the deltas, and the hyperons turn out to be in good agreement with experimental data as well as insights obtained from lattice QCD. The presented relativistic constituent-quark model should provide a solid basis for introducing QCD effects consistently into a variety of processes involving hadrons, reaching from particle to nuclear physics.

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