Type of Document	Dissertation
Author	Grigoryan, Hovhannes Roman
Author's Email Address	hgrigo1@jlab.org
URN	etd-07032008-100238
Title	Nonperturbative Dynamics of Strong Interactions from Gauge/Gravity Duality
Degree	Doctor of Philosophy (Ph.D.)
Department	Physics & Astronomy
Advisory Committee	Advisor Name Title Jerry Draayer Committee Chair Edward Zganjar Committee Member Lai-Him Chan Committee Member Thomas Kutter Committee Member William Metcalf Committee Member Oliver Dasbach Dean's Representative
Keywords	nonperturbative qcd form factor meson pion chern-simons ads/qcd model anomaly holographic duality ads extra dimensions
Date of Defense	2008-07-02
Availability	unrestricted
Abstract This thesis studies important dynamical observables of strong interactions such as form factors. It is known that Quantum Chromodynamics (QCD) is a theory which describes strong interactions. For large energies, one can apply perturbative techniques to solve some of the QCD problems. However, for low energies QCD enters into the nonperturbative regime, where different analytical or numerical tools have to be applied to solve problems of strong interactions. The holographic dual model of QCD is such an analytical tool that allows one to solve some nonperturbative QCD problems by translating them into a dual five-dimensional theory defined on some warped Anti de Sitter (AdS) background. Working within the framework of the holographic dual model of QCD, we develop a formalism to calculate form factors and wave functions of vector mesons and pions. As a result, we provide predictions of the electric radius, the magnetic and quadrupole moments which can be directly verified in lattice calculations or even experimentally. To find the anomalous pion form factor, we propose an extension of the holographic model by including the Chern-Simons term required to reproduce the chiral anomaly of QCD. This allows us to find the slope of the form factor with one real and one slightly off-shell photon which appeared to be close to the experimental findings. We also analyze the limit of large virtualities (when the photon is largely off-shell) and establish that predictions of the holographic model analytically coincide with those of perturbative QCD with asymptotic pion distribution amplitude. We also study the effects of higher dimensional terms in the AdS/QCD model and show that these terms improve the holographic description towards a more realistic scenario. We show this by calculating corrections to the vector meson form factors and corrections to the observables such as electric radii, magnetic and quadrupole moments.
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