Precision Measurements in Quantum Chromodynamics

Abstract

In this thesis, I present a series of theoretical developments and precision calculations in Quantum Chromodynamics (QCD) and collider physics, with a focus on collider observables sensitive to jet substructure. In particular, I propose a new family of observables called multi-point energy correlators and perform precision calculations of them using both fixed-order and effective field theory techniques. On the fixed-order side, I finish the analytic calculations of three-point correlator in $\mathcal{N}=4$ super Yang-Mills theory, QCD and Higgs boson decays and extract the asymptotic behaviors in various kinematic limits. Along the way, I also develop analytic techniques to compute physical observables in quantum field theory. The large logarithms arising from infrared divergences in the collinear limit and coplanar limits are resummed to all orders in perturbation theory through soft-collinear effective theory, improving its convergence and allowing for phenomenological applications. The collinear limit result for proton-proton collisions has been used to extract the value of strong coupling constant at the Large Hadron Collider. In addition, I also study another collider observable called heavy jet mass at electron-positron collider and apply the effective field theory technique to resum the remaining logarithms in the trijet region, which are referred to as Sudakov Shoulders. Integrating with the existing resummation in the dijet limit, and a renormalon-based model for non-perturbative power corrections, I also perform a global fit with experimental data to extract the strong coupling constant. To further improve the precision measurements at colliders, I derive a new factorization theorem for small-radius jet production, correcting the missing logarithms in the literature. To validate the factorization, I also develop a Monte Carlo program for calculating jet functions with a jet algorithm at two-loops. Using this formula, I push the precision of inclusive jet production spectrum at hadron colliders further and significantly improve its agreement with experimental data.