6,884 research outputs found
Chromatographic test facility. Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration
Test facility to verify design concepts and mathematical models of chromatograph for atmospheric composition analysis of Mar
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
The Reach of the Fermilab Tevatron and CERN LHC for Gaugino Mediated SUSY Breaking Models
In supersymmetric models with gaugino mediated SUSY breaking (inoMSB), it is
assumed that SUSY breaking on a hidden brane is communicated to the visible
brane via gauge superfields which propagate in the bulk. This leads to GUT
models where the common gaugino mass is the only soft SUSY breaking
term to receive contributions at tree level. To obtain a viable phenomenology,
it is assumed that the gaugino mass is induced at some scale beyond the
GUT scale, and that additional renormalization group running takes place
between and as in a SUSY GUT. We assume an SU(5) SUSY GUT above
the GUT scale, and compute the SUSY particle spectrum expected in models with
inoMSB. We use the Monte Carlo program ISAJET to simulate signals within the
inoMSB model, and compute the SUSY reach including cuts and triggers approriate
to Fermilab Tevatron and CERN LHC experiments. We find no reach for SUSY by the
Tevatron collider in the trilepton channel. %either with or without %identified
tau leptons. At the CERN LHC, values of (1160) GeV can be probed
with 10 (100) fb of integrated luminosity, corresponding to a reach in
terms of of 2150 (2500) GeV. The inoMSB model and mSUGRA can likely
only be differentiated at a linear collider with sufficient energy to
produce sleptons and charginos.Comment: 17 page revtex file with 9 PS figure
Probing Minimal Supergravity at the CERN LHC for Large
For large values of the minimal supergravity model parameter , the
tau lepton and the bottom quark Yukawa couplings become large, leading to
reduced masses of -sleptons and -squarks relative to their first and
second generation counterparts, and to enhanced decays of charginos and
neutralinos to -leptons and -quarks. We evaluate the reach of the CERN
LHC collider for supersymmetry in the mSUGRA model parameter space. We
find that values of GeV can be probed with just 10
fb of integrated luminosity for values as high as 45, so
that mSUGRA cannot escape the scrutiny of LHC experiments by virtue of having a
large value of . We also perform a case study of an mSUGRA model at
where \tz_2\to \tau\ttau_1 and \tw_1\to \ttau_1\nu_\tau
with branching fraction. In this case, at least within our
simplistic study, we show that a di-tau mass edge, which determines the value
of m_{\tz_2}-m_{\tz_1}, can still be reconstructed. This information can be
used as a starting point for reconstructing SUSY cascade decays on an
event-by-event basis, and can provide a strong constraint in determining the
underlying model parameters. Finally, we show that for large there
can be an observable excess of leptons, and argue that signals
might serve to provide new information about the underlying model framework.Comment: 22 page REVTEX file including 8 figure
Effects of systemic and non-systemic stresses on the thermal characteristics of corn
Experiments were conducted on corn plants using a calibrated spectroradiometer under field conditions in the indium antimonide channel (InSb, 2.8 to 5.6 mm) and the mercury cadmium telluride channel (HgCdTe, 7 to 14 mm). A ground cover experiment, an experiment on nonsystemic corn plants, and an experiment on systemic-stressed corn plants were included. The average spectral radiance temperature of corn plant populations was found (1) to be statistically significantly different for four healthy corn plant populations, (2) to increase with increased blight severity, and (3) to be statistically significantly different for varying rates of nitrogen applications
South Dakotans at Work
The nation\u27s industries-and the jobs associated with those industries-are being created, destroyed, or moved at an accelerating pace. The impact on the U.S. economy is large, and the western plains states of the North-Central Region have been particularly vulnerable to these changes. In South Dakota the changes have been especially dramatic
SIGNALS FOR MINIMAL SUPERGRAVITY AT THE CERN LARGE HADRON COLLIDER: MULTI-JET PLUS MISSING ENERGY CHANNEL,
We use ISAJET to perform a detailed study of the missing transverse energy
\eslt plus multi-jet signal expected from superparticle production at the
CERN LHC. Our analysis is performed within the framework of the minimal
supergravity model with gauge coupling unification and radiative electroweak
symmetry breaking. We delineate the region of parameter space where the \eslt
supersymmetry signal should be observable at the LHC and compare it to the
regions explorable via searches for sleptons and for chargino/neutralino
production. We confirm that, given a data sample of 10~\fb^{-1}, GeV can be explored if m_{\tq}\gg m_{\tg}, while GeV
can be probed if m_{\tq}\simeq m_{\tg}. We further examine what information
can be gleaned from scrutinizing this event sample. For instance, the multi-jet
multiplicity yields information on whether squark production makes a
significant contribution to the observed \eslt sample. Furthermore,
reconstructing hemispheric masses may yield a measure of to . Finally, for favourable ranges of parameters, by reconstructing
masses of tagged jet pairs, it may be possible to detect Higgs
bosons produced via sparticle cascade decay chains.Comment: 22 pages (REVTEX); a PS text file (etmiss.ps) and 12 figures
(etlhc.uu or etlhc.ps) can be obtained via anonymous ftp at
ftp://hep.fsu.edu/anonymous.bae
Hidden SUSY at the LHC: the light higgsino-world scenario and the role of a lepton collider
While the SUSY flavor, CP and gravitino problems seem to favor a very heavy
spectrum of matter scalars, fine-tuning in the electroweak sector prefers low
values of superpotential mass \mu. In the limit of low \mu, the two lightest
neutralinos and light chargino are higgsino-like. The light charginos and
neutralinos may have large production cross sections at LHC, but since they are
nearly mass degenerate, there is only small energy release in three-body
sparticle decays. Possible dilepton and trilepton signatures are difficult to
observe after mild cuts due to the very soft p_T spectrum of the final state
isolated leptons. Thus, the higgsino-world scenario can easily elude standard
SUSY searches at the LHC. It should motivate experimental searches to focus on
dimuon and trimuon production at the very lowest p_T(\mu) values possible. If
the neutralino relic abundance is enhanced via non-standard cosmological dark
matter production, then there exist excellent prospects for direct or indirect
detection of higgsino-like WIMPs. While the higgsino-world scenario may easily
hide from LHC SUSY searches, a linear e^+e^- collider or a muon collider
operating in the \sqrt{s}\sim 0.5-1 TeV range would be able to easily access
the chargino and neutralino pair production reactions.Comment: 20 pages including 12 .eps figure
Trilepton Signature of Minimal Supergravity at the Upgraded Tevatron
The prospects for detecting trilepton events ( or ) from
chargino-neutralino () associated production are
investigated for the upgraded Fermilab Tevatron Collider in the context of the
minimal supergravity model (mSUGRA). In some regions of parameter space,
and decay dominantly into final states with
leptons and the contributions from leptonic decays enhance the trilepton
signal substantially when soft cuts on lepton transverse momenta are used.
Additional sources of the mSUGRA trilepton signal and dominant irreducible
backgrounds are discussed. The dilepton () invariant mass
distribution near the endpoint is considered as a test of mSUGRA mass
relations. Discovery contours for at 2 TeV with an
integrated luminosity of 2 fb to 30 fb are presented in the
mSUGRA parameter space of for several choices of .Comment: Version to appear in Physical Review
Probing Slepton Mass Non-Universality at e^+e^- Linear Colliders
There are many models with non-universal soft SUSY breaking sfermion mass
parameters at the grand unification scale. Even in the mSUGRA model scalar mass
unification might occur at a scale closer to M_Planck, and renormalization
effects would cause a mass splitting at M_GUT. We identify an experimentally
measurable quantity Delta that correlates strongly with delta m^2 =
m^2_{selectron_R}(M_GUT) - m^2_{selectron_L}(M_GUT), and which can be measured
at electron-positron colliders provided both selectrons and the chargino are
kinematically accessible. We show that if these sparticle masses can be
measured with a precision of 1% at a 500 GeV linear collider, the resulting
precision in the determination of Delta may allow experiments to distinguish
between scalar mass unification at the GUT scale from the corresponding
unification at Q ~ M_Planck. Experimental determination of Delta would also
provide a distinction between the mSUGRA model and the recently proposed
gaugino-mediation model. Moreover, a measurement of Delta (or a related
quantity Delta') would allow for a direct determination of delta m^2.Comment: 15 pages, RevTeX, 4 postscript figure
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