1997/09/12 by Jens O. Andersen, J. O. Andersen, Andersen, J. O.
Earth and Planetary Sciences · Mathematics · Physics and Astronomy · #FOS: Physical sciences #Gas Dynamics and Kinetic Theory #High Energy Physics - Phenomenology (hep-ph) #High-pressure geophysics and materials #hep-ph #nanoparticles nucleation surface interactions
paper · pdf · doi:10.48550/arxiv.hep-ph/9709331
PH. D. thesis June 1997, 132 pages, LATEX, 60 figures appear in text
arxiv created 1997/09/12 · openalex publication_date 1997/09/12 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Chapter one is devoted to a study of fermions and bosons in two spatial dimensions in external electromagnetic fields. The effectve action is calculated by integrating out the matter fields. In chapter two, I investigate the resummation program of Braaten and Pisarski. I calculate the screening mass squared and the free energy in Yukwava theory to two and three-loop order, respectively, in resummed perturbation theory. The main part of the present work is on effective field theories at finite temperature. I discuss the concepts of dimensional reduction, modern renormalization theory, and renormalizable field theories (``fundamental theories'') versus non-renormalizable theories (``effective theories''). Two methods for constructing effective three dimensional field theories are discussed. The first is based on the effective potential, and is applied to field theory with N charged U(N) symmetric scalar coupled to an Abelian gauge field. The second method is an effective field theory approach based on diagrammatical methods, recently developed by Braaten and Nieto. I apply the methods to various problems in spinor and scalar QED.