Measuring the beam-spin asymmetry π⁰ production off the neutron with CLAS12

Naidoo, Paul (2023) Measuring the beam-spin asymmetry π⁰ production off the neutron with CLAS12. PhD thesis, University of Glasgow.

Abstract

Over the course of the last couple of decades, Generalised Parton Distributions (GPDs) have become a compelling area of focus in both theoretical and experimental research in the field of hadronic structure. GPDs can be indirectly accessed via observables in hard exclusive reactions such as Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). In these reactions, an incident lepton scatters off an individual quark within the target nucleon via the exchange of a virtual photon, and a real photon (DVCS) or a meson (DVMP) are emitted as a result.

This thesis presents an analysis of Deeply Virtual π⁰ Meson Production off the deuteron (nDVπ⁰P). The data were taken with the CLAS12 detector, which is housed in the experimental Hall B at the Jefferson National Laboratory (JLab) in Virginia, USA. A longitudinally polarised electron beam delivered by JLab’s Continuous Electron Beam Accelerator Facility (CEBAF), at an energy of 10.2 and 10.6 GeV, was incident on a liquid deuterium target housed within the CLAS12 detector assembly.

The nDVπ⁰P channel is sensitive to the lesser-studied chiral-odd transversity GPDs. GPDs are accessed indirectly via observables related to the cross-sections of hard exclusive processes. One such example is the beam-spin asymmetry (𝐴LU) as a function of Trento-ɸ, the angle between the leptonic plane and the hadronic plane which are defined with the beam and scattered electron, and with the recoiling neutron and reconstructed π⁰, respectively. Despite the limited statistics, the observable (𝐴LU) was successfully extracted for eight kinematic bins (four in Mandelstam 𝑡 and two in 𝑥𝐵). This is a first measurement for nDVπ⁰P in the phase-space which is now available with CLAS12 in the 12 GeV era of JLab.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QB Astronomy; Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Sokhan, Dr. Daria and McKinnon, Dr. Bryan
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83892
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 31 Oct 2023 16:43
• Last Modified: 31 Oct 2023 16:45
• Thesis DOI: 10.5525/gla.thesis.83892
• URI: https://theses.gla.ac.uk/id/eprint/83892