Exclusive QCD Factorization and Single Transverse Polarization Phenomena at High-Energy Colliders

TL;DR

This thesis advances understanding of QCD by exploring exclusive scattering processes and spin phenomena at high energies, introducing new processes and observables to probe partonic structures and polarization effects at the LHC.

Contribution

It introduces two novel processes for better GPD sensitivity and proposes new jet substructure observables for detecting single transverse polarization at the LHC.

Findings

Enhanced sensitivity to GPD $x$ dependence

New jet substructure observables for polarization detection

Potential for improved LHC phenomenology

Abstract

This Ph.D.~thesis is divided into two distinct parts. The first part focuses on hard exclusive scattering processes in Quantum Chromodynamics (QCD) at high energies, while the second part delves into spin phenomena at the Large Hadron Collider (LHC). Hard exclusive scattering processes play a crucial role in QCD at high energies, providing unique insights into the confined partonic dynamics within hadrons, complementing inclusive processes. Studying these processes within the QCD factorization approach yields the generalized parton distribution (GPD), a nonperturbative parton correlation function that offers a three-dimensional tomographic parton image within a hadron. However, the experimental measurement of these processes poses significant challenges. This thesis will review the factorization formalism for related processes, examine the limitations of some widely used processes, and introduce two novel processes that enhance the sensitivity to GPD, particularly its dependence on the parton momentum fraction $x$. The second part of the thesis centers on spin phenomena, specifically single spin production, at the LHC. Noting that a single transverse polarization can be generated even in an unpolarized collision, this research proposes two new jet substructure observables: one for boosted top quark jets and another for high-energy gluon jets. The observation of these phenomena paves the way for innovative tools in LHC phenomenology, enabling both precision measurements and the search for new physics.