3 research outputs found
Constraining Z' From Supersymmetry Breaking
We suggest and analyze a class of supersymmetric Z' models based on the gauge
symmetry U(1)_x = x Y - (B-L), where Y is the Standard Model hypercharge. For 1
< x < 2, the U(1)_x D-term generates positive contributions to the slepton
masses, which is shown to solve the tachyonic slepton problem of anomaly
mediated supersymmetry breaking (AMSB). The resulting models are very
predictive, both in the SUSY breaking sector and in the Z' sector. We find M_Z'
= (2-4) TeV and the Z-Z' mixing angle \xi = 0.001. Consistency with symmetry
breaking and AMSB phenomenology renders the Z' "leptophobic", with Br(Z' -> e^+
e^-) = (1-1.6)% and Br(Z' -> q q-bar) = 44%. The lightest SUSY particle is
either the neutral Wino or the sneutrino in these models.Comment: 34 pages in LaTe
TeV-Scale Horizontal Symmetry and the Slepton Mass Problem of Anomaly Mediation
We propose a new scenario for solving the tachyonic slepton mass problem of
anomaly mediated supersymmetry breaking models with a non-Abelian horizontal
gauge symmetry broken at the TeV scale. A specific model based on SU(3)_{H}
horizontal symmetry is presented wherein the sleptons receive positive
mass-squared from the asymptotically free SU(3)_{H} gauge sector. Approximate
global symmetries present in the model strongly suppress flavor changing
processes induced by the horizontal vector gauge bosons. The model predicts
m_{h} < 120 GeV for the lightest Higgs boson mass, tan{beta} nearly equal to 4,
and M_V = 1-4 TeV for the SU(3)_{H} gauge boson masses. The lightest SUSY
particle is found to be the neutral Wino, which is a candidate for cold dark
matter.Comment: 25 pages in LaTeX, 2 eps figure
Electroweak Symmetry Breaking via UV Insensitive Anomaly Mediation
Anomaly mediation solves the supersymmetric flavor and CP problems. This is
because the superconformal anomaly dictates that supersymmetry breaking is
transmitted through nearly flavor-blind infrared physics that is highly
predictive and UV insensitive. Slepton mass squareds, however, are predicted to
be negative. This can be solved by adding D-terms for U(1)_Y and U(1)_{B-L}
while retaining the UV insensitivity. In this paper we consider electroweak
symmetry breaking via UV insensitive anomaly mediation in several models. For
the MSSM we find a stable vacuum when tanbeta < 1, but in this region the top
Yukawa coupling blows up only slightly above the supersymmetry breaking scale.
For the NMSSM, we find a stable electroweak breaking vacuum but with a chargino
that is too light. Replacing the cubic singlet term in the NMSSM superpotential
with a term linear in the singlet we find a stable vacuum and viable spectrum.
Most of the parameter region with correct vacua requires a large superpotential
coupling, precisely what is expected in the ``Fat Higgs'' model in which the
superpotential is generated dynamically. We have therefore found the first
viable UV complete, UV insensitive supersymmetry breaking model that solves the
flavor and CP problems automatically: the Fat Higgs model with UV insensitive
anomaly mediation. Moreover, the cosmological gravitino problem is naturally
solved, opening up the possibility of realistic thermal leptogenesis.Comment: 27 pages, 3 figures, 1 tabl