Glueball phenomenology within a nonlocal approach [Elektronische Ressource] / vorgelegt von Francesco Giacosa

Glueball phenomenologywithin a nonlocal approachDissertationzur Erlangung des Grades einesDoktors der Naturwissenschaftender Fakultat fur Mathematik und Physikder Eberhard-Karls-Universitat zu Tubingenvorgelegt vonFrancesco Giacosaaus Turin, Italien2005Tag der mundlic hen Prufung: 22. April 2005Dekan: Prof. Dr. Peter Schmid1. Berichterstatter: Prof. Dr. Dr. h. c. mult. Amand F assler2. Berichterstatter: Prof. Dr. Thomas GutscheAbstractIn this thesis we describe the properties of glueball phenomenology within a nonlocal covariantconstituent approach.The search for glueballs, their theoretical description and the mixing with quarkoniamesons is an active and unsolved issue of hadronic QCD. Di eren t models and assignementshave been proposed, but up to now no certain statement about their existence can be done.After introducing the theoretical framework in which we will work in, the attention will befocused on the problem of the scalar glueball, which lattice QCD predicts to be the lightestgluonic state with a mass between 1.4-1.8 GeV. In the same mass region one encountersmany scalar resonances; mixing between the bare glueball and quarkonia states is thereforelikely. In a covariant constituent approach one cannot de ne rigorously a mixing matrixconnecting the bare to physical elds. However, we propose a de nition which satis es thecorrect requirements and which can be compared to other phenomenological studies.