This project will carry out studies in the physics hadrons, which are the observable composites of quarks and gluons. These studies are relevant to the phenomenology of two kinds of hadrons, namely mesons and baryons, as well as to the further understanding of the complex non-perturbative domain of the fundamental theory of strong interactions known as Quantum Chromodynamics (QCD). One of these studies will address the phenomenology of excited baryons by means of a theoretical framework known as the 1/N expansion of QCD, where N is the number of color degrees of freedom, equal to three in nature. The main goal of this study is to describe masses, strong decays and processes of photo-production of excited baryons with a framework that is consistent with the strictures of QCD. This plan is of relevance to the current experimental program on excited baryons at Jefferson Lab. Theoretical studies of some fundamental aspects of the 1/N expansion will also be carried out, especially with focus on the phenomenon of spontaneous breaking of chiral symmetry in QCD. Another study will address the problem of describing QCD at low and intermediate energies with effective theories. In particular, the project will consider the problem of extending the range of validity of the low energy effective theory of QCD known as Chiral Perturbation Theory. The plan is to formulate an effective theory where low-lying meson resonances are included as active degrees of freedom. This new effective theory will help describe with better accuracy processes that take place outside the range of applicability of ordinary Chiral Perturbation Theory. In summary, the objective of the project is in the study of the physics of the strong interactions by means of methods that are consistent with QCD, and the main aim is to arrive in this way at rigorous results that have general validity. The project has also an important education component that includes the training of a PhD student, collaboration with postdoctoral associates, and the development of computer based teaching materials for graduate courses.
