Date Awarded

2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Physics

Advisor

Justin Stevens

Committee Member

David Armstrong

Committee Member

Jozef Dudek

Committee Member

Keith Griffioen

Committee Member

Volker Crede

Abstract

Hadron spectroscopy is a cornerstone of our understanding of the strong nuclear interac-tions. Studying the hadron spectrum led to the postulation of quarks and gluons, and the development of Quantum Chromodynamics (QCD), the theory of the strong nuclear force. Today hadron spectroscopy provides an important test of QCD, particularly in the non-perturbative energy regime. One such test is the existence of hybrid hadrons that have gluonic degrees of freedom, e.g. qq̄g states, that are allowed by QCD but have remained elusive in experimental searches. The GlueX experiment located at Thomas Jefferson National Accelerator Facility, is designed to map the light meson spectrum, including hybrid mesons, produced by a linearly polarized photon beam that is scattered off of a liquid hydrogen target. This dissertation concerns the installation and commissioning of the GlueX DIRC upgrade and the analysis of three reactions measured by the GlueX experiment. The GlueX DIRC is a particle identification detector installed as an upgrade to the GlueXexperiment in 2019 to improve the experiment’s ability to distinguish pions and kaons. The DIRC uses Cherenkov photons radiated by charged particles that travel faster than the speed of light in the detector medium to determine the velocity of said particles. The velocity measurement is used in conjunction with momentum measurements from other detectors to determine the mass of the particle. The DIRC will be essential to the future of strange meson spectroscopy in GlueX. The reactions γp → K + K − π + π − p, γp → K + K − π 0 π 0 p, γp → K + K − π 0 ηp were initiallychosen for this analysis to search for the hybrid meson candidate φ(2170) and related resonances. The φ(2170) has been observed in e + e − collider experiments decaying to K + K − π + π − and K + K − π 0 π 0 , among other final states. The φ(2170) was not observed in this analysis. The reaction γp → K + π + π − Λ(1520), a subset of the γp → K + K − π + π − p reaction, was analyzed with a Partial Wave Analysis (PWA) in order to study strange mesons that decay to K + π + π − . In the PWA, a useful model for the angular distributions was found but no significant structures could be observed due to statistical limitations.

DOI

https://dx.doi.org/10.21220/s2-b26x-tb15

Rights

© The Author

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