Sökning: "perturbation-theory"
Visar resultat 1 - 5 av 95 avhandlingar innehållade ordet perturbation-theory.
1. Multiconfigurational perturbation theory
Sammanfattning : The aim of the thesis is to analyze a method which describes the electron correlation in atoms and molecules. The method is based on Rayleigh-Schrödinger perturbation theory with a partitioning of the Hamiltonian into a fairly simple zeroth-order operator and a perturbation operator. LÄS MER
2. Topics in perturbation theory : From IBP identities to integrands
Sammanfattning : In this thesis we present different topics in perturbation theory. We start by introducing the method of integration by parts identities, which reduces a generic Feynman integral to a linear combination of a finite basis of master integrals. LÄS MER
3. The Powers of Perturbation Theory : Loops and Gauge Invariance in Particle Physics
Sammanfattning : The Standard Model is the best particle physics theory we have, but there are still phenomena that it cannot explain. In this thesis I have worked on two different projects that connect to two of the biggest unsolved questions of the Standard Model. LÄS MER
4. Time-Dependent Many-Body Perturbation Theory: Possibilities and Limitations
Sammanfattning : This dissertation investigates the possibilities and limitations of time-dependent many-body perturbation theory by studying small Hubbard clusters for which the exact solution is available. The first part of the thesis is comprised of a short introduction to the concepts and methodologies used. LÄS MER
5. Pion and Kaon Dynamics at Higher Orders in Chiral Perturbation Theory
Sammanfattning : Higher orders calculations of processes involving the pion and kaon pseudo-scalar mesons are presented in the framework of three flavour Chiral Perturbation Theory. The purpose is two-fold. First determining the low energy constants of ChPT that are necessary for higher accuracy predictions. LÄS MER