Low Energy Supersymmetry in Warped Brane Worlds

We discuss physical implications of the four-dimensional effective supergravity, that describes low-energy physics of the Randall--Sundrum model with moduli fields in the bulk and charged chiral matter living on the branes. Cosmological constant can be cancelled through the introduction of a brane Polonyi field and a brane superpotential for the 4d dilaton. We deduce a generalization of the effective 4d action to the case of a general, not necessarily exponential, warp factor. We note, that breakdown of supersymmetry in generic warped models may lead to the stabilization of the interbrane distance.Comment: 9 pages, Latex, Talk given at SUSY'01, June 11-17 2001, Dubna, Russi

Warped brane world supergravity, flipping, and the Scherk-Schwarz mechanism

We demonstrate the relation between the Scherk-Schwarz mechanism and flipped gauged brane-bulk supergravities in five dimensions. We discuss the form of supersymmetry violating Scherk-Schwarz terms in pure supergravity and in supergravity coupled to matter. Although the Lagrangian mass terms that arise as the result of the Scherk-Schwarz redefinition of fields are naturally of the order of the inverse radius of the orbifold, the effective 4d physical mass terms are rather set by the scale \sqrt{|\bar{\Lambda}|}, where \bar{\Lambda} is the 4d cosmlogical constant.Comment: 9 pages, talk given at the 1st International Conference on String Phenomenology, Oxford, UK, July 6 - 11, 200

Singular gauge transformations and supersymmetry breakdown on warped orbifolds

We have analyzed the breakdown of global supersymmetry by a non-vanishing expectation value of the fifth component of the graviphoton on warped S^1/Z_2 orbifolds. It has been demonstrated that the setups where such a breakdown is possible correspond to the models where the true gauge symmetry on the orbifold, respecting the Z_2-parities and periodicity, is broken by boundary terms. In the tuned models, giving Randall-Sundrum warp factor, gauge symmetry stays intact, and any can be gauged away without violating supersymmetry.Comment: 11 pages, Latex, version published in Phys. Lett.

Boundary Terms in Brane Worlds

We clarify the relation between orbifold and interval pictures in 5d brane worlds. We establish this correspondence for Z_2-even and Z_2-odd orbifold fields. In the interval picture Gibbons-Hawking terms are necessary to fulfill consistency conditions. We show how the brane world consistency conditions arise in the interval picture. We apply the procedure to the situation where the transverse dimension is terminated by naked singularities. In particular, we find the boundary terms needed when the naive vacuum action is infinite.Comment: 15 pages, plain Latex, typos correcte

Racetrack models in theories from extra dimensions

We have investigated moduli stabilization leading to hierarchical supersymmetry breakdown in racetrack models with two moduli fields simultaneously present in the effective racetrack superpotential. We have shown that stabilization of moduli occurs when a shift symmetry of the moduli space becomes gauged. This gauging results in a D-term contribution to the scalar potential that depends on moduli scalars. To break supersymmetry at a minimum created this way in the case where only a single combination of moduli is present in the superpotential one needs supergravity corrections. If the superpotential depends on two independent combinations of moduli, supersymmetry is broken by non-vanishing F-terms without supergravity terms. Some of the minima that we see correspond to a non-vanishing expectation value of the blowing-up modulus in the case of type IIB orientifold models. We point out that the mass of the gauge boson associated with gauged shift symmetry becomes naturally light in warped compactifications.Comment: latex, 10 pages, 1 figure, references adde