Hiroyuki Abe

We discuss the dimensional reduction of five-dimensional supergravity compactified on S^1/Z_2 keeping the N=1 off-shell structure. Especially we clarify the roles of the Z_2-odd N=1 multiplets in such an off-shell dimensional reduction. Their equations of motion provide constraints on the Z_2-even multiplets and extract the zero modes from the latter. The procedure can be applied to wide range of models and performed in a background-independent way. We demonstrate it in some specific models.

We study 5-dimensional supergravity on S^1/Z_2 with a physical Z_2-odd vector multiplet, which yields an additional modulus other than the radion. We derive 4-dimensional effective theory and find additional terms in the Kahler potential that are peculiar to the multi moduli case. Such terms can avoid tachyonic soft scalar masses at tree-level, which are problematic in the single modulus case. We also show that the flavor structure of the soft terms are different from that in the single modulus case when hierarchical Yukawa couplings are generated by wavefunction localization in the fifth dimension. We present a concrete model that stabilizes the moduli at a supersymmetry breaking Minkowski minimum, and show the low energy sparticle spectrum.

We study (4+2n)-dimensional N=1 super Yang-Mills theory on the orbifold background with non-vanishing magnetic flux. In particular, we study zero-modes of spinor fields. The flavor structure of our models is different from one in magnetized torus models, and would be interesting in realistic model building.

We discuss the nature of sequestering supersymmetry breaking sectors in a certain class of moduli stabilization in supergravity/string models, where a negative vacuum energy of the nonperturbative moduli potential is canceled by dynamically generated F-terms. Two illustrating examples are shown to sketch the issues around the supersymmetry breaking, flavors and sequestering within such a framework.

We study concretely several issues altogether, moduli stabilization, the dynamical supersymmetry (SUSY) breaking, the uplifting of SUSY anti-de Sitter (AdS) vacuum and the sequestering of hidden sector, in a simple supergravity model with a single extra dimension. The sequestering is achieved dynamically by a wavefunction localization in extra dimension. The expressions for the visible sector soft SUSY breaking terms as well as the hidden sector potential are shown explicitly in our model. We find that the tree-level soft scalar mass and the A-term can be suppressed at a SUSY breaking Minkowski minimum where the radius modulus is stabilized, while gaugino masses would be a mirage type.

We study the scenario that conformal dynamics leads to metastable supersymmetry breaking vacua. At a high energy scale, the superpotential is not R-symmetric, and has a supersymmetric minimum. However, conformal dynamics suppresses several operators along renormalization group flow toward the infrared fixed point. Then we can find an approximately R-symmetric superpotential, which has a metastable supersymmetry breaking vacuum, and the supersymmetric vacuum moves far away from the metastable supersymmetry breaking vacuum. We show a 4D simple model. Furthermore, we can construct 5D models with the same behavior, because of the AdS/CFT dual.

We present a systematic way for deriving a four-dimensional (4D) effective action of the five-dimensional (5D) orbifold supergravity respecting the N=1 {\it off-shell} structure. As an illustrating example, we derive a 4D effective theory of the 5D gauged supergravity with a universal hypermultiplet and {\it generic} gaugings, which includes the 5D heterotic M-theory and the supersymmetric Randall-Sundrum model as special limits of the gauging parameters. We show the vacuum structure of such model, especially the nature of moduli stabilization, introducing perturbative superpotential terms at the orbifold fixed points.

We study a four-dimensional effective theory of the five-dimensional (5D) gauged supergravity with a universal hypermultiplet and perturbative superpotential terms at the orbifold fixed points. Among eight independent isometries of the scalar manifold, we focus on three directions for gauging by the graviphoton. The class of models we consider includes the 5D heterotic M-theory and the supersymmetric Randall-Sundrum model as special limits of the gauging parameters. We analyze the vacuum structure of such models, especially the nature of moduli stabilization, from the viewpoint of the effective theory. We also discuss the uplifting of supersymmetric anti-de Sitter vacua.