FCNC in SUSY theories

URL: http://www-spht.cea.fr/articles/T96/003 (sur invitation). FCNC dans les théories SUSY http://fr.arxiv.org/abs/hep-ph/9601225International audienceRecent work on flavour changing neutral current effects in supersymmetric models is reviewed. The emphasis is put on new issues related to solutions to the flavour problem through new symmetries: GUTs, horizontal symmetries, modular invariances

Some Supersymmetric Flavour Problems

URL: http://www-spht.cea.fr/articles/t99/155/ Quelques problèmes supersymétriques reliés aux saveursCours, Seminaire, Ecole, School NATO advances Cargèse Summer School on Hierarchies of Fermion Masses and Gauge InteractionsSome Supersymmetric Flavour Problems | Quelques problèmes supersymétriques reliés aux saveur

Charge and Colour Breaking Constraints in the MSSM With Non-Universal SUSY Breaking

We examine charge/colour breaking along directions in supersymmetric field space which are F and D-flat. We catalogue the dangerous directions and include some new ones which have not previously been considered. Analytic expressions for the resulting constraints are provided which are valid for all patterns of supersymmetry breaking. As an example we consider a recently proposed pattern of supersymmetry breaking derived in Horava-Witten M-theory, and show that there is no choice of parameters for which the physical vacuum is a global minimum.Comment: 12 Pages plain latex; includes 1 postscript figure. Final version to appear in PL

Charged Lepton Flavour and CP Violations: Theoretical Impact of Present and Future Experiments

We shortly review and emphasize how l_j -> l_i gamma experiments and the searches for lepton e.d.m. are constraining New Physics model building. They are pure signals of new phenomena around the TeV scale since the SM contributions are definitely negligible. It is quite remarkable that they also give effective tests of the LFV & CPV in seesaw couplings and in grand-unified theories. In particular, the limits on d_e nicely complement the proton decay bounds in selecting O(10) models.Comment: 6 pages, 3 figures, Proceedings of Neutrino 04 (College de France, Paris

Constraints on Phases of Supersymmetric Flavour Conserving Couplings

In the unconstrained MSSM, we reanalyze the constraints on the phases of supersymmetric flavour conserving couplings that follow from the electron and neutron electric dipole moments (EDM). We find that the constraints become weak if at least one exchanged superpartner mass is >O(1 TeV) or if we accept large cancellations among different contributions. However, such cancellations have no evident underlying symmetry principle. For light superpartners, models with small phases look like the easiest solution to the experimental EDM constraints. This conclusion becomes stronger the larger is the value of $\tan\beta$. We discuss also the dependence of $\epsilon_K$, $\Delta m_B$ and $b\to s\gamma$ decay on those phases.Comment: 38 pages, 22 figures, uses epsfig.sty, axodraw.sty (not included); error in sign of gluino contribution to EDM of u and d quarks and few figures corrected, important conclusions unchange

Up Quark Masses from Down Quark Masses

The quark and charged lepton masses and the angles and phase of the CKM mixing matrix are nicely reproduced in a model which assumes SU(3)xSU(3) flavour symmetry broken by the v.e.v.'s of fields in its bi-fundamental representation. The relations among the quark mass eigenvalues, m_u/m_c \approx m_c/m_t \approx m^2_d/m^2_s \approx m^2_s/m^2_b \approx \Lambda^2_{GUT}/M^2_{Pl}, follow from the broken flavour symmetry. Large tan(beta) is required which also provides the best fits to data for the obtained textures. Lepton-quark grandunification with a field that breaks both SU(5) and the flavour group correctly extends the predictions to the charged lepton masses. The seesaw extension of the model to the neutrino sector predicts a Majorana mass matrix quadratically hierarchical as compared to the neutrino Dirac mass matrix, naturally yielding large mixings and low mass hierarchy for neutrinos.Comment: 11 pages, 1 figure. Published version: model improved, references adde

Abelian Flavour Symmetries in Supersymmetric Models

We propose a theory of flavour based on abelian horizontal gauge symmetries and modular invariances. We construct explicit supergravity models where the scale of the horizontal $U(1)$ symmetry breaking is fixed by the Green-Schwarz mechanism for anomaly cancellation. The supersymmetric spectrum is obtained in terms of the $U(1)$ charges which are determined by the Yukawa matrices.Comment: 30 pages, LaTeX, no figure

ISS-flation

Inflation may occur while rolling into the metastable supersymmetry-breaking vacuum of massive supersymmetric QCD. We explore the range of parameters in which slow-roll inflation and long-lived metastable supersymmetry breaking may be simultaneously realized. The end of slow-roll inflation in this context coincides with the spontaneous breaking of a global symmetry, which may give rise to significant curvature perturbations via inhomogenous preheating. Such spontaneous symmetry breaking at the end of inflation may give rise to observable non-gaussianities, distinguishing this scenario from more conventional models of supersymmetric hybrid inflation.Comment: 26 page

SUPERSYMMETRY BREAKING IN THE NAMBU-JONA-LASINIO APPROACH

Gaugino condensation in the hidden sector of supergravity models is described within a Nambu-Jona-Lasinio type of approach by minimization of a one-loop scalar potential. The essential ingredients of the mechanism are auxiliary superfields whose v.e.v. generate gaugino condensation and supersymmetry breaking, introduced through Lagrange multipliers. For phenomenologically acceptable values of the gauge couplings, gaugino condensation is disfavoured in this approach. For completeness, it is shown that supersymmetry breaking would occur for a stronger coupling, but at a scale inconsistent with the expectations.Comment: 15 pages, plain tex, no figure

Soft scalar masses in supergravity with horizontal U(1)_X gauge symmetry

In supergravity with modular invariance and horizontal $U(1)_X$ gauge symmetry there is a relation between modular weights and $U(1)_X$ charges. The soft scalar masses are then strongly correlated with Yukawa matrices. The implications for FCNC are discussed.Comment: 15 pages, LaTeX, Eq.(16) correcte