85 research outputs found
Simulating Supersymmetry with ISAJET 7.0/ ISASUSY 1.0
We review the physics assumptions and input used in ISAJET~7.0 /
ISA\-SUSY~1.0 that are relevant for simulating fundamental processes within the
framework of the Minimal Supersymmetric Standard Model (MSSM) at and
colliders. After a brief discussion of the underlying MSSM framework, we
discuss event simulation and list the sparticle production processes and decay
modes that have been incorporated into our calculations. We then describe how
to set up and run an ISAJET / ISASUSY job and the user input and output
formats. The ISAJET program is sufficiently flexible that some non-minimal
supersymmetry scenarios may be simulated as well. Finally, plans for future
upgrades which include the extension to collisions, are listed.Comment: 17 pages, FSU-HEP-930329 UH-511-764-9
Yukawa Coupling Unification in Supersymmetric Models
We present an updated assessment of the viability of t-b-tau Yukawa coupling
unification in supersymmetric models. For the superpotential Higgs mass
parameter mu>0, we find unification to less than 1% is possible, but only for
GUT scale scalar mass parameter m_{16}~8-20 TeV, and small values of gaugino
mass m_{1/2}<400 GeV. Such models require that a GUT scale mass splitting
exists amongst Higgs scalars with m_{H_u}^2<m_{H_d}^2. Viable solutions lead to
a radiatively generated inverted scalar mass hierarchy, with third generation
and Higgs scalars being lighter than other sfermions. These models have very
heavy sfermions, so that unwanted flavor changing and CP violating SUSY
processes are suppressed, but may suffer from some fine-tuning requirements.
While the generated spectra satisfy b->s gamma and (g-2)_mu constraints, there
exists tension with the dark matter relic density unless m_{16}<3 TeV. These
models offer prospects for a SUSY discovery at the Fermilab Tevatron collider
via the search for chargino_1 neutralino_2 -> 3 leptons events, or via gluino
pair production. If mu<0, Yukawa coupling unification to less than 5% can occur
for m_{16} and m_{1/2}>1-2 TeV. Consistency of negative mu Yukawa unified
models with b->s gamma, (g-2)_mu, and relic density all imply very large values
of m_{1/2} typically greater than about 2.5 TeV, in which case direct detection
of sparticles may be a challenge even at the LHC.Comment: 38 pages, 15 figures. Fig.15 changed, some references were added. A
copy of the paper with better resolution figures can be found at
http://www.hep.fsu.edu/~balazs/Physics/Papers/2003
Supersymmetry Reach of Tevatron Upgrades: The Large Case
The Yukawa couplings of the tau lepton and the bottom quark become comparable
to, or even exceed, electroweak gauge couplings for large values of the SUSY
parameter . As a result, the lightest tau slepton \ttau_1 and
bottom squark \tb_1 can be significantly lighter than corresponding sleptons
and squarks of the first two generations. Gluino, chargino and neutralino
decays to third generation particles are significantly enhanced when
is large. This affects projections for collider experiment reach
for supersymmetric particles. In this paper, we evaluate the reach of the
Fermilab Tevatron collider for supersymmetric signals in the
framework of the mSUGRA model. We find that the reach via signatures with
multiple isolated leptons ( and ) is considerably reduced. For very
large , the greatest reach is attained in the multi-jet+\eslt
signature. Some significant extra regions may be probed by requiring the
presence of an identified -jet in jets+\eslt events, or by requiring one
of the identified leptons in clean trilepton events to actually be a hadronic 1
or 3 charged prong tau. In an appendix, we present formulae for chargino,
neutralino and gluino three body decays which are valid at large .Comment: 31 page Revtex file including 10 PS figure
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