54 research outputs found
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
Testing the AMSB Model via }
The possibility of detecting the signature of a nearly invisible charged wino
(\CH) decaying into a soft pion and the LSP(\LSP), predicted by the Anomaly
Mediated Symmetry Breaking model, via the process
at the Next Linear Collider
has been explored. Using the recently, proposed bounds on slepton and wino
masses derived from the condition of stability of the electroweak symmetry
breaking vacuum and employing some standared kinematical cuts to supress the
background, we find that almost the whole of the allowed parameter space with
the slepton mass less than 1 TeV, can be probed at 500 GeV.
Determination of the slepton and the chargino masses from this signal is a
distinct possiblity. Any violation of the above mass bound will suggest that
the standard vacuum is unstable and we are living in a false vacuum.Comment: 10pages, Latex style, 4 figs, revised versio
QCD corrections to the decay in the Minimal Supersymmetric Standard Model
We present a complete calculation of the QCD corrections (of the order
) to the width of the decay within the Minimal
Supersymmetric Standard Model. We find that the QCD corrections are quite
important, and that the supersymmetric QCD corrections (due to gluino, stop and
sbottom exchange) can be comparable to or even larger than the standard QCD
corrections in a large region of the supersymmetric parameter space. This is
mainly due to the effect of large left-right mixings of stop and sbottom. This
could significantly affect the phenomenology of the search.Comment: 12 pages latex, 5 uuencoded figures, LateX file of text and PS-files
of the text and the figures are also available via anonymous ftp at
ftp://info.oeaw.ac.at/pub/hephy-pub/631 . Figures have been changed (and fig.
5 added), and accordingly the discussion of thes
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
Complete two-loop effective potential approximation to the lightest Higgs scalar boson mass in supersymmetry
I present a method for accurately calculating the pole mass of the lightest
Higgs scalar boson in supersymmetric extensions of the Standard Model, using a
mass-independent renormalization scheme. The Higgs scalar self-energies are
approximated by supplementing the exact one-loop results with the second
derivatives of the complete two-loop effective potential in Landau gauge. I
discuss the dependence of this approximation on the choice of renormalization
scale, and note the existence of particularly poor choices which fortunately
can be easily identified and avoided. For typical input parameters, the
variation in the calculated Higgs mass over a wide range of renormalization
scales is found to be of order a few hundred MeV or less, and is significantly
improved over previous approximations.Comment: 5 pages, 1 figure. References added, sample test model parameters
listed, minor wording change
Low-Energy Supersymmetry and its Phenomenology
The structure of low-energy supersymmetric models of fundamental particles
and interactions is reviewed, with an emphasis on the minimal supersymmetric
extension of the Standard Model (MSSM) and some of its variants. Various
approaches to the supersymmetry-breaking mechanism are considered. The
implications for the phenomenology of Higgs bosons and supersymmetric particles
at future colliders are discussed.Comment: 20 pages, 2 figures, LaTeX with espcrc2.sty, invited talk at the "30
Years of Supersymmetry" Symposium, Minneapolis, Minnesota, 13--15 October
200
Higgs Boson Theory and Phenomenology
Precision electroweak data presently favors a weakly-coupled Higgs sector as
the mechanism responsible for electroweak symmetry breaking. Low-energy
supersymmetry provides a natural framework for weakly-coupled elementary
scalars. In this review, we summarize the theoretical properties of the
Standard Model (SM) Higgs boson and the Higgs sector of the minimal
supersymmetric extension of the Standard Model (MSSM). We then survey the
phenomenology of the SM and MSSM Higgs bosons at the Tevatron, LHC and a future
e+e- linear collider. We focus on the Higgs discovery potential of present and
future colliders and stress the importance of precision measurements of Higgs
boson properties.Comment: 90 pages, 31 figures. Revised version. To be published in Progress in
Particle and Nuclear Physics. This paper with higher resolution figures can
be found at http://scipp.ucsc.edu/~haber/higgsreview/higgsrev.p
SUSY-QCD corrections to stop and sbottom decays into Higgs bosons
We calculate the order(\alpha_s) SUSY-QCD corrections to the widths of stop
and sbottom decays into Higgs bosons within the Minimal Supersymmetric Standard
Model. We give the complete analytical formulae paying particular attention to
the on-shell renormalization of the soft SUSY-breaking parameters. We also
perform a detailed numerical analysis of both stop and sbottom decays into all
Higgs bosons h^0, H^0, A^0, and H^\pm. We find that the SUSY-QCD corrections
are significant, mostly negative and of the order of a few ten percent.Comment: revised version, one figure and a few comments adde
Signals of anomaly mediated supersymmetry breaking in an e^- gamma collider
We study the signatures of minimal anomaly mediated supersymmetry breaking in
an e^- gamma collider. We demonstrate that the associated production of a
sneutrino with the lightest chargino leads to a substantially large signal
size. The background is negligibly small, though. Even more interestingly, a
measurement of the fundamental supersymmetry breaking parameters could be
possible.Comment: 25 pages, LaTex, 7 PS figures and 1 table (included
The Case for a Muon Collider Higgs Factory
We propose the construction of a compact Muon Collider Higgs Factory. Such a
machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean
Higgs events per year, enabling the most precise possible measurement of the
mass, width and Higgs-Yukawa coupling constants.Comment: Supporting letter for the document: "Muon Collider Higgs Factory for
Smowmass 2013", A White Paper submitted to the 2013 U.S. Community Summer
Study of the Division of Particles and Fields of the American Physical
Society, Y. Alexahin, et. al, FERMILAB-CONF-13-245-T (July, 2013
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