Applications of Light-Front Quantization in QED and QCD

The goal of this thesis is to present some novel applications of the light-front quantization formalism to the fields of Quantum Electrodynamics (QED) and Quantum Chromodynamics (QCD). Light-Front quantization proves to be an elegant language for the description of a composite particle in terms of its elementary constituents; as such, it has recently become a very effective language for Quantum Field Theories and, in particular, for Hadronic Physics. we first provide an intriduction to the light-front formalism and study the gauge-field propagator in light-cone gauge. We then introduce the partonic distribution functions on the light cone and calculate the Transverse-Momentum Dependent (TMDs) and the Generalized TMDs (GTMDs) in the context of QED, thus obtaining a multi-dimensional picture of the electron cloud. We finally address the problem of properly defining angular-momentum densities inside the nucleon.