6,759 research outputs found
Sleptonarium (Constraints on the CP and Flavour Pattern of Scalar Lepton Masses)
The constraints on the flavour and CP structure of scalar lepton mass
matrices are systematically collected. The display of the resulting upper
bounds on the lepton -slepton misalignment parameters is designed for an easy
inspection of very large classes of models and the formula are arranged so as
to suggest useful approximations. Interferences among the different
contributions to lepton flavour violating transitions and lepton electric and
magnetic dipole moments of generic character can either tighten or loose the
bounds. A combined analysis of all rare leptonic transitions can disentangle
the different contributions to yield hints on several phenomenological issues.
The possible impact of these results on the study of the slepton misalignment
originated in the seesaw mechanism and grand-unified theories is emphasized
since the planned experiments are getting close to the precision required in
such tests.Comment: 29 pages, 13 figures; v3: corrected misprints in appendix
Models with Inverse Sfermion Mass Hierarchy and Decoupling of the SUSY FCNC Effects
We study the decoupling of the first two squark and slepton families in order
to lower the flavour changing neutral current effects. Models with inverse
sfermion mass hierarchy based upon gauged U(1) flavour symmetries provide a
natural framework where decoupling can be implemented. Decoupling requires a
large gap between the Fermi scale and the supersymmetry breaking scale.
Maintaining the electroweak symmetry breaking at the Fermi scale requires some
fine-tuning that we investigate by solving the two-loop renormalization group
equations. We show that the two-loop effects are governed by the anomaly
compensated by the Green-Schwarz mechanism and can be determined from the quark
and lepton masses. The electroweak breaking constraints lead to a small
scenario where the LSP is Higgsino-like.Comment: 19 pages, Latex, 1 Postscript figur
Supersymmetric Flat Directions and Analytic Gauge Invariants
We review some aspects of the correspondence between analytic gauge
invariants and supersymmetric flat directions for vanishing D-terms and propose
a criterion to include the F-term constraints.Comment: 8 pages, Late
Geometrical approach to duality in N=1 supersymmetric theories
We investigate the geometry of the moduli spaces of dual electric and
magnetic N=1 supersymmetric field theories. Using the SU(N_c) gauge group as a
guideline we show that the electric and magnetic moduli spaces coincide for a
suitable choice of the Kahler potential of the magnetic theory. We analyse the
Kahler structure of the dual moduli spaces.Comment: 14 pages, LaTe
Intermediate Symmetries in the Spontaneous Breaking of Supersymmetric SO(10)
We study the supersymmetric spontaneous symmetry breaking of SO(10) into
SU(3)xSU(2)xU(1) for the most physically interesting cases of SU(5) or flipped
SU(5)xU(1) intermediate symmetries. The first case is more easily realized
while the second one requires a fine-tuning condition on the parameters of the
superpotential. This is because in the case of SU(5) symmetry there is at most
one singlet of the residual symmetry in each SO(10) irreducible representation.
We also point out on more general grounds in supersymmetric GUT's that some
intermediate symmetries can be exactly realized and others can only be
approximated by fine-tuning. In the first category, there could occur some
tunneling between the vacua with exact and approximate intermediate symmetry.
The flipped SU(5)xU(1) symmetry improves the unification of gauge couplings if
(B-L) is broken by (B-L)=1 scalars yielding right handed neutrino masses below
10^{14} GeV}.Comment: LaTex, 9 page
Chiral Extensions of the MSSM
We present a class of extensions of the MSSM characterized by a fully chiral
field content (no mu-terms) and no baryon or lepton number violating term in
the superpotential due to an extra U'(1) gauge symmetry. The minimal model
consist of the usual matter sector with family dependent U'(1) charges, six
Higgs weak doublets, and three singlets required to give masses to the
Higgsinos and cancel anomalies. We discuss its main features such as the tree
level mass spectrum and the constraints on flavor changing processes.Comment: 13 pages. V2: Superpotential and U'(1) charges changed. Analysis of
the spectrum for the new model added. References update
Quark flavour conserving violations of the lepton number
We study supersymmetric models of lepton and baryon number violation based on an abelian family gauge group. Due to possible lepton-Higgs mixing, the lepton violating couplings are related to the Yukawa couplings and may be generated by them even if they were absent in the original theory. Such terms may be dominant and are not given by the naive family charge counting rules. This enhancement mechanism can provide an alignment between lepton-number violating terms and Yukawa couplings: as a result they conserve quark flavour. A natural way of suppressing baryon number violation in this class of models is also proposed
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