Hadronic Decays of Baryon Resonances

The project aims at a theoretical description of mesonic decays of baryon resonances following a microscopic approach along constituent quark models. All the calculations are performed in a relativistic framework observing Poincaré invariance. Specifically, one considers the pion and eta decay modes of nucleon and delta resonances, later on also kaon decays of strange resonances. The investigations are started with the specific constituent quark model based on Goldstone-boson-exchange dynamics. The corresponding decay widths are studied in comparison with the available experimental data and previous nonrelativistic results. In parallel, one calculates analogous covariant results from other constituent quark models, notably the one-gluon-exchange model, in order to find out the influences of different quark dynamics on the resonance decays. In addition one examines the performances of certain relativistic formulations. Likewise different models for the decay mechanism are investigated. Subsequently, explicit pionic (and possibly further mesonic) degrees of freedom are introduced into the resonance wave functions via a coupled-channels approach. This new class of wave functions, which yield a more realistic description of baryon resonance states, should finally allow for an essentially improved approach to decay widths. Within this project four main issues are examined with regard to the present understanding of mesonic baryon decays: i) the role of relativistic effects; ii) the influence of the kind of dynamics between constituent quarks; iii) the adequacy of specific meson decay operators; and iv) the importance of explicit mesonic degrees of freedom in baryon resonance wave functions.

The project aims at a theoretical description of mesonic decays of baryon resonances following a microscopic approach along constituent quark models. All the calculations are performed in a relativistic framework observing Poincaré invariance. Specifically, one considers the pion and eta decay modes of nucleon and delta resonances, later on also kaon decays of strange resonances. The investigations are started with the specific constituent quark model based on Goldstone-boson-exchange dynamics. The corresponding decay widths are studied in comparison with the available experimental data and previous nonrelativistic results. In parallel, one calculates analogous covariant results from other constituent quark models, notably the one-gluon-exchange model, in order to find out the influences of different quark dynamics on the resonance decays. In addition one examines the performances of certain relativistic formulations. Likewise different models for the decay mechanism are investigated. Subsequently, explicit pionic (and possibly further mesonic) degrees of freedom are introduced into the resonance wave functions via a coupled-channels approach. This new class of wave functions, which yield a more realistic description of baryon resonance states, should finally allow for an essentially improved approach to decay widths. Within this project four main issues are examined with regard to the present understanding of mesonic baryon decays: i) the role of relativistic effects; ii) the influence of the kind of dynamics between constituent quarks; iii) the adequacy of specific meson decay operators; and iv) the importance of explicit mesonic degrees of freedom in baryon resonance wave functions.