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Doctoral Thesis
DOI
10.11606/T.43.1996.tde-03122013-183606
Document
Author
Full name
Silvana Pilar Flego
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1996
Supervisor
Committee
Nemes, Maria Carolina (President)
Escobar, Bruto Max Pimentel
Gomes, Marcelo Otavio Caminha
Silva, Adilson Jose da
Thomaz, Maria Teresa Climaco dos Santos
Title in Portuguese
Uma versão regularizada do modelo σ-linear
Keywords in Portuguese
Cromodinâmica quântica
Abstract in Portuguese
Usualmente os modelos efetivos utilizados para a descrição da física de hádrons de baixa energia não são renormalizáveis. O objetivo da presente investigação é discutir o papel da renormalização no tratamento de um modelo efetivo. Estudamos o Modelo -Linear na sua versão renormalizada e descobrimos a presença de polos fantasmas. Investigamos então as consequências de introduzir na teoria um parâmetro cutoff, , com a precaução de manter no possível as propriedades de simetria da Lagrangiana original. Mostramos que nessa versão regularizada os pólos não-físicos desaparecem quando o parâmetro cutoff é menor ou da ordem de IND.C 1.2 GeV. É possível fixar o valor de em IND.C e interpretar autoconsistentemente as propriedades físicas associadas com os propagadores. Uma ressonância centrada em 880 MeV com uma largura de 400 MeV aparece no propagador sigma; o nucleon é um estado ligado e no seu continuo duas ressonâncias de Roper podem ser identificadas.
Title in English
A regularized version of the σ-linear model
Keywords in English
Quantum chromodynamics
Abstract in English
Usually the effective model utilized for the description of low energy hadron physics are not renormalizable. The purpose of the present investigation is to discuss the role of the renormalization in the treatment of a effective model. We study the -Linear Model in it renormalized version and find the presence of ghost poles. We then investigate the consequences of introducing into the theory a cutoff , taking care of maintaining the symmetry properties of the original Lagrangian. We show that in the regularized version the nonphysical poles disappear when the cutoff parameter value is less than IND.C 1.2 GeV. It is possible to fix cutoff value in IND.C and get a selfconsistent interpretation of physical properties associated with the propagators. A resonance centered at 880 MeV with a corresponding width 400 MeV appear in the sigma propagator. The nucleon is a bound state and in its continuum two Roper resonances can be identified.
 
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45622PilarFlego.pdf (1.52 Mbytes)
Publishing Date
2014-02-18
 
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