Title page for ETD etd-07062007-112158

Type of Document Dissertation
Author Matevosyan, Hrayr Hamlet
URN etd-07062007-112158
Title Exploring the Quark-Gluon Content of Hadrons: From Mesons to Nuclear Matter
Degree Doctor of Philosophy (Ph.D.)
Department Physics & Astronomy
Advisory Committee
Advisor Name Title
Jerry Draayer Committee Chair
Anthony Thomas Committee Co-Chair
James Matthews Committee Member
William Metcalf Committee Member
Marcio Dequeiroz Dean's Representative
  • QCD
  • 1/Nc expansion
  • Lattice QCD
  • QMC
Date of Defense 2007-06-22
Availability unrestricted
Even though Quantum Chromodynamics (QCD) was formulated over three

decades ago, it poses enormous challenges for describing the properties of hadrons

from the underlying quark-gluon degrees of freedom. Moreover, the problem of

describing the nuclear force from its quark-gluon origin is still open. While a direct

solution of QCD to describe the hadrons and nuclear force is not possible at this

time, we explore a variety of developed approaches ranging from phenomenology

to first principle calculations at one or other level of approximation in linking the

nuclear force to QCD.

The Dyson Schwinger formulation (DSE) of coupled integral equations for the

QCD Greenís functions allows a non-perturbative approach to describe hadronic

properties, starting from the level of QCD n-point functions. A significant approx-

imation in this method is the employment of a finite truncation of the system of

DSEs, that might distort the physical picture. In this work we explore the effects

of including a more complete truncation of the quark-gluon vertex function on the

resulting solutions for the quark 2-point functions as well as the pseudoscalar and

vector meson masses. The exploration showed strong indications of possibly large

contributions from the explicit inclusion of the gluon 3- and 4-point functions that

are omitted in this and previous analyses. We then explore the possibility of ex-

trapolating state of the art lattice QCD calculations of nucleon form factors to the

physical regime using phenomenological models of nucleon structure.

Finally, we further developed the Quark Meson Coupling model for describing

atomic nuclei and nuclear matter, where the quark-gluon structure of nucleons is

modeled by the MIT bag model and the nucleon many body interaction is mediated

by the exchange of scalar and vector mesons. This approach allows us to formulate a

fully relativistic theory, which can be expanded in the nonrelativistic limit to repro-

duce the well known phenomenological Skyrme-type interaction density functional,

thus providing a direct link to well modeled nuclear forces. Moreover, it allows

for a derivation of the equation of state for cold uniform dense nuclear matter for

application to calculations of the properties of neutron stars.

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