2014-06-132014-06-132009-03MACIEL, Soraya Galdino. Efeitos de temperatura e potencial químico em Teoria Quântica de Campos. 2009. 53 f. Dissertação (Mestrado) - Universidade Federal do Pará, Instituto de Ciências Exatas e Naturais, Belém, 2009. Programa de Pós-Graduação em Física.https://repositorio.ufpa.br/handle/2011/5059In this work we study the e ects of a nonzero chemical potential in (1 + 1) dimensions quantum eld models at nite temperature. We particularly consider massless fermions in an abelian gauge eld background and calculate the e ective action by evaluating the n-point functions. We nd that the structure of the amplitudes corresponds to a generalization of the structure noted earlier in a calculation found in the literature without a chemical potential (the associated integrals carry the dependence on the chemical potential). Our calculation shows that the chiral anomaly is una ected by the presence of a chemical potential at nite temperature. However, unlike in the absence of a chemical potential, odd point functions do not vanish. In fact, we nd that all the even point functions are even functions of while the odd point functions are odd functions of . We show that the origin of the structure of the amplitudes is best seen from a formulation of the theory in terms of left and right handed spinors. The calculations are also much simpler in this formulation and it clari es many other aspects of the theory.porAcesso AbertoTeoria quântica de camposModelo SchwingerDissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA GERAL::FISICA CLASSICA E FISICA QUANTICA MECANICA E CAMPOS