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| Author(s): |
Fátima Araujo Machado
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. 2014-06-11. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Física Teórica (IFT). São Paulo |
| Defense date: | 2011-03-30 |
| Advisor: | Adriano A. Natale |
| Abstract | |
The present work concerns the ghost-gluon vertex of Quantum Chromodynamics, which, according to the Taylor identity, has no perturbative corrections to any order, in the Landau gauge and for a specific momentum configuration. We study this vertex for a momentum configuration for which there is no proof of such a result, which is the one with a zero gluon momentum. The framework we adopt for it is the Dynamical Perturbation Theory approach, which consists of inserting some nonperturbative information of the theory into its perturbative expansion. It is a phenomenological attempt only, intended to probe infrared properties of the theory by means of loop calculations. We have made use of two nonperturbative informations: First, a finite gluon mass, since there are even more indications that the gluon presents a mass, though it is a dynamical one – it intrinsically changes from finite in the infrared, to zero in the ultraviolet. Second, a recent result on the effective charge of Quantum Chromodynamics, which itself considers a dynamical gluon mass. We calculate the 1-loop correction to the ghost-gluon vertex, aiming at verifying how close to 1 the ghost-gluon vertex renormalization function (~Z1) is. The result obtained was positive in this direction: ~Z1 does not differ much from unity, as shown in Chap.5. Moreover, our result ts better the lattice data when we consider the mentioned effective charge, than when we set the coupling constant as a t parameter. Therefore, our somewhat phenomenological approach based on a dynamical gluon mass is, at least, consistent, and supports the approximation ~Z1 1, usually performed in the study of the Schwinger-Dyson equations of Quantum Chromodynamics (AU) | |
| FAPESP's process: | 09/10968-7 - Radiative corrections in QCD taking the effect of dynamical mass generation into account. |
| Grantee: | Fatima Araujo Machado |
| Support Opportunities: | Scholarships in Brazil - Master |