Date of Award

Summer 8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Program/Concentration

Physics

Committee Director

Stepan Stepanyan

Committee Member

Lawrence Weinstein

Committee Member

Ted Rogers

Committee Member

Alexander Godunov

Committee Member

Sandipan Dutta

Abstract

J/ψ production (heavy quarkonium in general) is sensitive to the gluonic content of the nucleon. Recent theoretical studies have suggested that near-threshold J/ψ production is sensitive to the gravitational form factors (GFFs) of the nucleon, which parametrize the matrix elements of the QCD energy-momentum tensor (EMT). The energy-momentum tensor of the nucleon encodes its mechanical properties through the gravitational form factors, which give access to quantities such as the mass radius and pressure distribution of the proton. Previous J/ψ electroproduction measurements were either performed near-threshold at very low Q2 (in the quasi-real photoproduction regime) or far above threshold at higher Q2. The near-threshold electroproduction regime at finite Q2 remains unexplored.

This dissertation presents the first measurement of near-threshold J/ψ electroproduction using the CLAS12 detector at Jefferson Lab. The analysis targets the exclusive reaction ep→e′p′J/ψ, with the J/ψ reconstructed via its e+e− decay channel and the scattered electron detected in the Forward Tagger, covering 4.15 < W < 4.48 GeV and 0.02 < Q2 < 0.12 GeV2. The total cross-section is extracted in three W bins. The results are then compared with the recent CLAS12 near-threshold J/ψ photoproduction cross-section. Finally, this works provides the first measurement of the Q2 dependence of this process in the near-threshold regime.

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DOI

10.25777/bc2f-st95

ISBN

9798193214243

ORCID

0009-0003-7645-1289

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Nuclear Commons

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