2002/08/11 by T. Watari, T. Yanagida, Watari, T. +1
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th) #hep-ph #hep-th
paper · pdf · doi:10.48550/arxiv.hep-ph/0208107
61 pages
arxiv created 2002/08/11 · arxiv updated 2009/11/30
The doublet--triplet mass splitting problem is one of the most serious problems in supersymmetric grand unified theories (GUTs). A class of models based on a product gauge group, such as the SU(5)GUT times U(3)H or the SU(5)GUT times U(2)H, realize naturally the desired mass splitting that is protected by an unbroken R symmetry. It has been pointed out that various features in the models suggest that these product-group unification models are embedded in a supersymmetric brane world. We show an explicit construction of those models in the supersymmetric brane world based on the Type IIB supergravity in ten dimensions. We consider T6/(Z12 times Z2) orientifold for the compactified six extra dimensions. We find that all of the particles needed for the GUT-symmetry-breaking sector are obtained from the D-brane fluctuations. The three families of quarks and leptons are introduced at an orbifold singularity, although their origin remains unexplained. This paper includes extensive discussion on anomaly cancellation in a given orbifold geometry. Relation to the Type IIB string theory, realization of R symmetry as a rotation of extra-dimensional space, and effective superpotential at low energies are also discussed.