Dipolos de cor e interações a altas energias

• Main Author: Maria Simone Kugeratski Souza
• Other Authors: Fernando Silveira Navarra
• Language: Portuguese
• Published: Universidade de São Paulo 2007
• Subjects: Fenomenologia; F\\\'isica de part\\\' iculas; Satura\\c\\~ao de gluons; Gluon saturation; Particle physics; Phenomenology
• Online Access: http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17122007-095340/

A altas energias o n\\\'ucleon (ou o n\\\'ucleo) pode ser visto como um sistema denso de gl\\\'uons, o condensado de vidro de cor. Neste trabalho estudamos a intera\\c\\~ao deste sistema com dipolos de cor. Esta intera\\c\\~ao \\\'e representada pela se\\c\\~ao de choque dipolo-alvo, a qual \\\'e modelada. Utilizamos alguns dos modelos propostos na literatura para descrever os dados do HERA e do RHIC e propusemos uma nova parametriza\\c\\~ao que \\\'e capaz de descrever estes dados simultaneamente, demonstrando a propriedade de universalidade do condensado de vidro de cor. Generalizamos o modelo proposto por Iancu, Itakura e Munier para o caso nuclear e o aplicamos ao estudo de espalhamento el\\\'etron-n\\\'ucleo. Estimamos a influ\\^encia dos efeitos de satura\\c\\~ao nos observ\\\'aveis que ser\\~ao medidos no futuro eRHIC. Conclu\\\'imos entre outras coisas, que uma grande fra\\c\\~ao dos eventos observados ser\\~ao do tipo difrativo. Finalmente usamos a id\\\'eia de dipolo de cor para estudar a se\\c\\~ao de choque charmonium-h\\\'adron. === At high energies a nucleus (and even a nucleon) becomes a dense gluonic system called the color glass condensate. In this work we study the interaction of this dense system with color dipoles. This interaction is represented by the dipole-target cross section, which has to be modeled. We have used, without success, some of the existing models to try to reproduce the data obtained at HERA and RHIC. It was not possible to obtain a global agreement between the models and the two sets of data. We have then proposed a different parametrization of the dipole cross section, which is now compatible with all the available data. In the case of deep inelastic scattering, we have extended the Iancu-Itakura-Munier model to nuclear targets and made predictions for observables to be measured in the future electron-ion collider eRHIC. Among other things, we have concluded that a large fraction of the events will be of the diffractive type. Finally, we have used the color dipole approach to build a simple model for the charmonium-hadron interaction at high energies.