Loops in QED and Leading order rates of Positronium hydride

Abstract

The wealth of data from the Large Hadron Collider (LHC) brought us to an era of pre cision experimental data. It requires equally precise theoretical descriptions, particularly the radiative corrections in di erent Quantum Electrodynamics (QED) and Quantum Chromodynamics (QCD) processes. The rst part of this dissertation reviews the theo retical techniques used to calculate one-loop QED diagrams analytically. However, there are processes where the tree-level diagrams for them are enough to compare the theoretical results with some ongoing and future experiments. The second part discusses the decay of positronium hydride (PsH) to an electron and a proton's nal state. We calculate the decay rates by considering a particular spin of the PsH in the initial state and for the general spin con guration.