Physics Master of Science Thesis Defense by Anudeep Davuluru
Abstract:
Quark confinement is a phenomenon observed in the strong interaction that cannot be derived using conventional perturbative techniques and requires alternative approaches. Since the the-ory becomes strongly coupled in the infrared regime, perturbative methods fail to reproduce the hadron mass spectrum and the approximately linear Regge behavior observed experimentally.
This thesis investigates various approaches to quark confinement and develops criteria to classify different families of potentials based on whether they can produce confinement. The study be-gins with the generalized SU(3) framework developed by Dr. Hsu, using the quadratic confining potential that arises directly from generalized SU(3) symmetry. In this approach, confinement is described purely from the boundary gauge theory by constructing an effective quark potential from generalized SU(3) transformations. The resulting energy spectrum is computed and compared with the experimental baryon mass spectrum to assess how well this framework captures confinement behavior.
To further classify potentials capable of exhibiting confinement and to filter out non-viable cases, the AdS/QCD soft-wall model is considered, in which confinement is encoded through a dilaton profile that vanishes at the boundary and produces a discrete spectrum through a Schr¨odinger-like equation. By fitting the radial nucleon trajectory, a holographic scale κ = 0.48 GeV is extracted, consistent with phenomenological expectations for linear Regge behavior. However, in this model confinement is introduced through the choice of background fields rather than being derived dynamically from the spacetime geometry.
The analysis is then extended to the Einstein–dilaton action, where solving the coupled equa-tions of motion determines whether confinement emerges self-consistently from gravity. In this framework, I also study IHQCD-type potentials and impose swampland- and bootstrap-inspired constraints, including conditions on RG flow monotonicity, background smoothness, spectral positivity and discreteness, and stability under parameter variations, in order to filter out the class of viable confining models.
This analysis shows that only a restricted class of potentials satisfies all the imposed constraints, leading to a progressive shrinking of the allowed parameter space and providing a systematic way to identify viable confining models and reproduce linear Regge behavior.
Advisor:
Dr. J.P. Hsu, Department of Physics (jhsu@umassd.edu)
Committe Members:
Dr. David Kagan, Department of Physics
Dr. Robert Fisher, Department of Physics
Note:
All PHY Graduate Students are encouraged to attend.
SENG 201
Dr. J.P. Hsu
jhsu@umassd.edu