Beam Spin Asymmetry in Dihadron Final States with Kaons in Semi-inclusive Deep Inelastic Scattering

Abstract

The substructure of nucleons and how internal strong force dynamics generate their properties, such as mass and spin, is a topic of major experimental and theoretical investigation. One probe of nucleon substructure is dihadron semi-inclusive deep inelastic scattering (SIDIS), where a lepton exchanges a virtual photon with a quark in the nucleon and the scattered electron is measured along with two hadrons in the final state. The SIDIS cross section is sensitive to three-dimensional nucleon momentum structure encoded in Transverse Momentum Dependent Parton Distribution Functions (TMD-PDFs). It is also sensitive to the hadronization process, where a struck quark forms color-neutral hadrons, via Dihadron Fragmentation Functions (DiFFs). DiFFs provide unique sensitivity to the polarization of the struck quark and its impact on the final distribution of hadrons. In this dissertation, the beam spin asymmetry in dihadron SIDIS with charged kaon final states is measured for the first time with data collected using CLAS12. Comparison of this measurement to the same asymmetry for pion final states provides novel information on flavor dependence in hadronization. This measurement is also sensitive to twist-3 PDFs and DiFFs, which encode quark-gluon correlations. These results therefore provide further insight into the dynamic nature of nucleon substructure. This dissertation will also describe the development of an alignment method for the CLAS12 Ring Imaging Cherenkov detector using Bayesian optimization, extending the usable acceptance of the detector significantly for future particle ID in physics analyses with CLAS12.