Towers of positive parity excited baryons and their mixing in the large Nc limit

• Autores: Willemyns, Cintia Teresita; Schat, Carlos Luis
• Año de publicación: 2017
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Effective models in QCD; 1/Nc expansion of QCD; Excited baryons; Configuration Mixing
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We consider configuration mixing for the nonstrange positive parity excited baryons in the [56′,0+], [56,2+], [70,0+], and [70,2+] quark model SU(6)×O(3) multiplets contained in the N=2 band. Starting from the effective mass operator for these states, we show by an explicit calculation that in the large Nc limit they fall into six towers of degenerate states labeled by K=0,1,1′,2,2′,3. We find that the mixing of the spin-flavor states is much simpler than what is naively expected in the quark model. To leading order in Nc, only states carrying the same K label can mix, which implies that, for the spin-flavor states we started with, configuration mixing can be parameterized by just two constants: μK=1 and μK=2. The obtained mass degeneracies and mixing pattern constitute a signature of the contracted spin-flavor symmetry for baryons in the large Nc limit.
Fil: Willemyns, Cintia Teresita. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina
Fil: Schat, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Okumenisches Gymnasium zu Bremen; Alemania