GUT and standard-like models in intersecting D-brane worlds

Abstract

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.