Jet substructure at the LHC with soft collinear effective theory

This thesis investigates the use of Soft-Collinear effective theory (SCET) in order to obtain precise QCD predictions for jet substructure observables. We used SCET to obtain factorization theorems that allow us to resum towers of logarithms that become large in certain regions of phase space, improving the convergence of perturbation theory. Pushing for higher orders in logarithmic accuracy is a crucial part of having reliable predictions to be put up against data, and a necessary condition for precision. The jet substructure observables studied in this thesis are the jet shape, the angle between different jet axes, the jet energy drop, and the Soft Drop momentum sharing fraction z_g.