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Geração de termos com violação de simetria de Lorentz à temperatura finita / Generation of terms with violation of Lorentz symmetry at finite temperatureFreire, Wellington Romero Serafim 03 July 2015 (has links)
In this thesis, we investigated the generation of the higher derivative Chern-Simons term, as well as the ether-like term, both at finite temperature. We also examined the question of the large gauge invariance, with respect to the Chern-Simons term and the hight derivative one. We observed that the coefficient of the Chern-Simons term vanishes, when we taken into account the limit of high temperature. This happens to occur also for the other high derivative terms. With respects to the Chern-Simons term, we observed that the action of the Chern-Simons term and the high derivative one are invariant under the large gauge transformation. For this, we calculated the exactly effective action, however, for a specific gauge choice. Finally, with respects to the ether-like term, we observed that the calculation at finite temperature is ambiguous, as well as it is observed for the calculation at zero temperature. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta tese, investigamos a geração do termo de Chern-Simons de derivada superior, assim como o termo tipo éter, ambos à temperatura finita. Também estudamos a questão da invariância de gauge ampla, com o termo de Chern-Simons e Chern-Simons de derivada superior. Constatamos que o coeficiente do termo de Chern-Simons de derivada superior anula-se, quando tomamos o limite de altas temperaturas. Esse resultado parece se repetir para os demais termos de derivada superior. Dentro ainda do contexto de Chern-Simons, observamos que a ação de Chern-Simons e a ação de Chern-Simons de derivada superior são invariantes sob transformação de gauge ampla. Para isso, conseguimos calcular a ação efetiva exata, contudo, para uma escolha de gauge específica. Finalmente, com relação ao termo tipo éter, constatamos que o cálculo à temperatura finita e ambíguo, assim como observado no cálculo à temperatura zero.
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