We study the general patterns of SUSY-breaking soft terms arising under the assumption of Kahler moduli dominated SUSY-breaking in string theory models. Insisting that all MSSM gauginos get masses at leading order and that the top Yukawa coupling is of order the gauge coupling constant identifies the class of viable models. These are models in which the SM fields live either in the bulk or at the intersection of local sets of Type IIB D7-branes or their F-theory relatives. General arguments allow us to compute the dependence of the Kahler metrics of MSSM fields on the local Kahler modulus of the brane configuration in the large moduli approximation. We illustrate this study in the case of toroidal/orbifold orientifolds but discuss how the findings generalize to the F-theory case which is more naturally compatible with coupling unification. Only three types of 7-brane configurations are possible, leading each of them to very constrained patterns of soft terms for the MSSM. We study their consistency with radiative electroweak symmetry breaking and other phenomenological constraints. We find that essentially only the configuration corresponding to intersecting 7-branes is compatible with all present experimental constraints and the desired abundance of neutralino dark matter. The obtained MSSM spectrum is very characteristic and could be tested at LHC. We also study the LHC reach for the discovery of this type of SUSY particle spectra.

This work has been supported by the European Commission under RTN European Programs MRTN-CT-2004-503369, MRTN-CT-2004-005105, by the CICYT (Spain) under project FPA2006-01105, the Comunidad de Madrid under project HEPHACOS P-ESP-00346 and the Ingenio 2010 CONSOLIDER program CPAN. L. Aparicio acknowledges finantial support of the Ministerio de Educación y Ciencia of Spain through a FPU grant. D.G. Cerdeño is supported by the program “Juan de la Cierva” of the Ministerio de Educación y Ciencia of Spain, Ayudas de I+D S-0505/ESP-0346, and by the EU research and training network MRTN-CT-2006-035863.

Submitted on 19 May 2008 (v1), last revised 26 Jun 2008 (this version, v2).-- 60 pages, 7 figures, 2 tables. References added.

Peer reviewed