Thermal Effects in Quantum Gauge Theory at Finite Temperature

Author(s)

Rafael Rodrigues Francisco

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2014-08-26

Examining board members

Josif Frenkel; Fernando Tadeu Caldeira Brandt; Bruto Max Pimentel Escobar; Adilson Jose da Silva; Alfredo Takashi Suzuki

• Advisor: Josif Frenkel

Abstract

We have worked in three problems related to finite temperature gauge theory. The first one discusses the gauge invariance of the electron physical mass in an arbitrary dimension space at zero temperature. We have obtained the physical mass from the pole of the fermion propagator and we have demonstrated that the usual form to define this propagator works well for covariant gauges, but not for non covariant gauges. Then, we have proposed anew fermion propagator and we verified in two different ways that the physical mass obtained from this new one works for a gauge defined with control parameters so that it could be generalized for both classes studied. The second problem is on the n photon interaction in a space with (1+1) dimensions at hard thermal loops. Using the imaginary time formalism and the Schwinger\'s model, we have shown that all terms of the retarded causal amplitudes with one or more loops have null contribution. We have got a physical interpretation of this result and we have done a parallel of how it relates with the CPT invariance of this theory. The last one is related with quantum gravitation in (3+1) dimensions. We have discussed the possibility to obtain the 1PI n graviton functions in static and long-wavelength limits from polynomials which could be written and related in a simple manner. To this end, we used the Ward identities and the Weyl invariance to relate the n and (n+1) graviton functions. Then, we used the Boltzmann transport equation formalism to get a better understanding of the results. (AU)

• FAPESP's process: 10/20329-9 - Thermal effects in quantum gauge theory at finite temperature
• Grantee: Rafael Rodrigues Francisco
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)