
Type of Document Dissertation Author Matevosyan, Hrayr Hamlet URN etd07062007112158 Title Exploring the QuarkGluon 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 CoChair James Matthews Committee Member William Metcalf Committee Member Marcio Dequeiroz Dean's Representative Keywords
 QCD
 1/Nc expansion
 Lattice QCD
 QMC
Date of Defense 20070622 Availability unrestricted Abstract Even though Quantum Chromodynamics (QCD) was formulated over threedecades ago, it poses enormous challenges for describing the properties of hadrons
from the underlying quarkgluon degrees of freedom. Moreover, the problem of
describing the nuclear force from its quarkgluon 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 Green’s functions allows a nonperturbative approach to describe hadronic
properties, starting from the level of QCD npoint 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 quarkgluon vertex function on the
resulting solutions for the quark 2point 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 4point 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 quarkgluon 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 Skyrmetype 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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