568 research outputs found
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
. We discuss also the dependence of , and
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 symmetry breaking is fixed by the Green-Schwarz
mechanism for anomaly cancellation. The supersymmetric spectrum is obtained in
terms of the 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 gauge
symmetry there is a relation between modular weights and 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
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