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Abstract:
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The main goal of string phenomenology is to find a convincing connection be-
tween realistic particle physics and string theory. An extended object called D-brane
in string theory is shown as a very powerful tool to resolve phenomenology problems.
D-branes, D standing for Dirichlet boundary conditions, naturally appear in the T-
dual space along one of the toroidally compactified dimensions in non-perturbative
Type I theory. A D-brane forms an U(1) gauge group and the group structure can be
enriched by Chan-Paton indices with multiple coincided D-branes and orientifold ac-
tions. Oribfolds define fixed points of the compactified space and break the theory to
N = 1 supersymmetry, and the extended orientifold from world-sheet parity projects
the brane image to help cancel the anomalies. Strings at the intersections of two
D-branes (Type IIA) form massless chiral fermions as bi-fundamental representations
of the gauge groups of the intersecting branes. With these properties, we construct
Grand Unification Theory (GUT) and standard-like models by intersecting D-brane
configuration on T6/(Z2 × Z2) orientifold. Also, supergravity and geometrical fluxes
are introduced to stabilize the moduli. In this dissertation, first a brief review of the
D-brane theory is discussed, then the complete construction of D-brane configuration
on T6/(Z2 × Z2) is presented, and finally some realistic Trinification, Pati-Salam,
SU(5) and flipped SU(5) models are constructed and discussed. We present the
models both in D-brane wrapping numbers and the corresponding particle spectra. |
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