Precision Calculations of Parton Physics under Large Momentum Effective Theory

Abstract

Parton distributions are effective field theory (EFT) descriptions of the momentum distributions of quarks and gluons in a hadron moving at asymptotically large momentum. They serve as essential inputs for precision tests of the Standard Model (SM) and for searches for physics beyond the SM, as well as key probes of hadron structure. Large Momentum Effective Theory (LaMET) provides a systematic EFT framework to compute parton distributions through a large-momentum expansion and perturbative matching of Euclidean correlators accessible in lattice quantum chromodynamics (QCD). This dissertation provides a brief review of LaMET and presents two of the author’s PhD works within this framework. The first is an effort to control the precision in LaMET calculations: the large-distance asymptotic analysis of the Fourier transform. The second implements the LaMET analysis of the unpolarized $u-d$ proton PDF, which serves as a benchmark to calibrate the analysis procedure and demonstrate precision-control capability. These studies constitute important steps toward precision determinations of parton distributions within the LaMET framework.