Improved QCD Calculations and Phenomenological Studies at the Large Hadron Collider

In high-energy physics, particle collisions are modelled by computer programs called "Monte Carlo event generators". Their results can be compared directly to the results of real experiments. The choice between the many possible outcomes of a particle collision is based on random numbers. This game of chance, just as in a casino, is what "Monte Carlo" refers to. Comparisons between the measurements and the output of event generators make the latter a crucial tool for understanding collider physics and build the link between experiment and theory. The thesis aims at providing new models and improvements for event generators.