The Structure of Baryon Resonances

Hamiltonian Effective Field Theory (HEFT) is a non-perturbative extension of effective field theory which provides a bridge between the infinite-volume scattering data of ex- periment, and finite-volume energy spectra from lattice QCD. By discretising a Hamilto- nian which has been constrained to experimental scattering data, solving the eigenvalue equation for the Hamiltonian provides a finite-volume energy spectrum, which may be compared with lattice QCD eigenstates. In addition, eigenvectors of the Hamiltonian pro- vide insight into the structure of these eigenstates. This matrix Hamiltonian has been made finite by finite-range regularisation, and by considering the range of regularisation parameters which allow the Hamiltonian to describe experimental scattering data, insight is gained into the degree of model-dependence in the infinite-volume and finite-volume quantities. This formalism is extended for the first time to systems with multiple quark- model like baryon states. By considering the effect of a second bare basis state on both the infinite-volume poles, and finite-volume energy spectrum, we gain a unique intuition into the relationship between these two regimes. Finally, we apply the multiple bare-baryon formalism to the odd-parity nucleon sector. We find that the interpretation of the two odd-parity nucleons as three-quark cores dressed by πN , ηN , and KΛ two-particle states is consistent with both the experimental scattering data, and lattice QCD results at three lattice volumes. We also introduce a novel HEFT simulation of lattice QCD correlation functions, allowing for a determination of the two-particle scattering-state contamination in lattice QCD eigenstates.

Author dc:creator

• Abell, Curtis David

Advisors dc:contributor.advisor

• Leinweber, Derek
• Thomas, Anthony

• baryon resonances
• effective field theory
• scattering
• finite-volume

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2440/139724

OAI identifier oai:identifier

oai:digital.library.adelaide.edu.au:2440/139724