7,478 research outputs found
LOW ENERGY SUPERSYMMETRY PHENOMENOLOGY
We summarize the current status and future prospects for low energy (weak
scale) supersymmetry. In particular, we evaluate the capabilities of various
, and colliders to discover evidence for supersymmetric
particles. Furthermore, assuming supersymmetry is discovered, we discuss
capabilities of future facilities to dis-entangle the anticipated spectrum of
super-particles, and, via precision measurements, to test mass and coupling
parameters for comparison with various theoretical expectations. We comment
upon the complementarity of proposed hadron and machines for a
comprehensive study of low energy supersymmetry.Comment: 74 page (Latex) file; a PS or uuencoded manuscript with embedded
figures is available via anonymous ftp at
ftp://hep.fsu.edu/preprints/baer/FSUHEP950401.ps or .uu . Contributed chapter
to DPF study group on Electroweak Symmetry Breaking and Beyond the Standard
Model
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
Impact of R-Parity Violation on Supersymmetry Searches at the Tevatron
We evaluate cross sections for \eslt, 1 and various dilepton and
multilepton event topologies that result from the simultaneous production of
all sparticles at the Tevatron collider, both within the minimal model
framework as well as in two different -parity violating scenarios. Our
analysis assumes that these -violating couplings are small, and that their
sole effect is to cause the lightest supersymmetric particle to decay inside
the detector. We reassess future strategies for sparticle searches at the
Tevatron, and quantify by how much the various signals for supersymmetry could
differ from their minimal model expectations, if -parity is not conserved
due to either baryon number or lepton number violating operators. We also
evaluate the Tevatron reach in for the various models, and find that
rate-limited multilepton signals ultimately provide the largest reach for both
-parity conserving and -parity violating cases.Comment: preprint nos. FSU-HEP-941001, UR-1387, ER-40685-836 and
UH-511-807-94, 13 pages (REVTEX) plus 3 uuencoded figures attache
Prospects for Supersymmetry at LEP2
Working within the framework of the minimal supergravity model with gauge
coupling unification and radiative electroweak symmetry breaking (SUGRA), we
map out regions of parameter space explorable by experiments at LEP2, for
center of mass energy options of , and 205 GeV. We
compute signals from all accessible SUSY pair production
processes using the ISAJET simulation program, and devise cuts that enhance the
signal relative to Standard Model backgrounds, and which also serve to
differentiate various supersymmetric processes from one another. We delineate
regions of SUGRA parameter space where production of neutralino pairs, chargino
pairs, slepton pairs and the production of the light Higgs scalar of SUSY is
detectable above Standard Model backgrounds and distinguishable from other SUSY
processes. In addition, we find small regions of SUGRA parameter space where
\te\te, \tz_2\tz_2 and \tnu_L\tnu_L production yields spectacular events
with up to four isolated leptons. The combined regions of parameter space
explorable by LEP2 are compared with the reach of Tevatron Main Injector era
experiments. Finally, we comment on how the reach via the neutralino pair
channel is altered when the radiative electroweak symmetry breaking constraint
is relaxed.Comment: 22 page REVTEX file + 9 uuencoded figures; a uuencoded PS file with
PS figures is available via anonymous ftp at
ftp://hep.fsu.edu/preprints/baer/FSUHEP950501.u
SUPERSYMMETRY REACH OF AN UPGRADED TEVATRON COLLIDER
We examine the capability of a TeV Tevatron collider
to discover supersymmetry, given a luminosity upgrade to amass of
data. We compare with the corresponding reach of the Tevatron Main Injector
( of data). Working within the framework of minimal supergravity
with gauge coupling unification and radiative electroweak symmetry breaking, we
first calculate the regions of parameter space accessible via the clean
trilepton signal from \tw_1\tz_2\to 3\ell +\eslt production, with detailed
event generation of both signal and major physics backgrounds. The trilepton
signal can allow equivalent gluino masses of up to GeV to
be probed if is small. If is large, then GeV can
be probed for and large values of , the
rate for \tz_2\to\tz_1\ell\bar{\ell} is suppressed by interference effects,
and there is {\it no} reach in this channel. We also examine regions where the
signal from \tw_1\overline{\tw_1}\to \ell\bar{\ell}+\eslt is detectable.
Although this signal is background limited, it is observable in some regions
where the clean trilepton signal is too small. Finally, the signal
\tw_1\tz_2\to jets+\ell\bar{\ell} +\eslt can confirm the clean trilepton
signal in a substantial subset of the parameter space where the trilepton
signal can be seen. We note that although the clean trilepton signal may allow
Tevatron experiments to identify signals in regions of parameter space beyond
the reach of LEP II, the dilepton channels generally probe much the same region
as LEP II.Comment: 19 page REVTEX file; a uuencoded PS file with PS figures is available
via anonymous ftp at ftp://hep.fsu.edu/preprints/baer/FSUHEP950301.u
Contact Interactions and Resonance-Like Physics at Present and Future Colliders from Unparticles
High scale conformal physics can lead to unusual unparticle stuff at our low
energies. In this paper we discuss how the exchange of unparticles between
Standard Model fields can lead to new contact interaction physics as well as a
pseudoresonance-like structure, an unresonance, that might be observable at the
Tevatron or LHC in, e.g., the Drell-Yan channel. The specific signatures of
this scenario are quite unique and can be used to easily identify this new
physics given sufficient integrated luminosity.Comment: 20 pages, 10 figs; minor text changes, ref added; typos correcte
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
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
Supersymmetry Reach of the Tevatron via Trilepton, Like-Sign Dilepton and Dilepton plus Tau Jet Signatures
We determine the Tevatron's reach in supersymmetric parameter space in
trilepton, like-sign dilepton, and two lepton one tau-jet channels. We
critically study the standard model background processes. We find larger
backgrounds and, hence, significantly smaller reach regions than recent
analyses. We identify the major cause of the background discrepancy. We improve
signal-to-noise by introducing an invariant mass cut which takes advantage of a
sharp edge in the signal dilepton invariant mass distribution. Also, we
independently vary the cuts at each point in SUSY parameter space to determine
the set which yields the maximal reach. We find that this cut optimization can
significantly enhance the Tevatron reach.Comment: 30 pages, 10 figure
Anomaly-Free Gauged R-Symmetry
We review the gauging of an R-symmetry in local and global susy. We then
construct the first anomaly-free models. We break the R-symmetry and susy at
the Planck scale and discuss the low-energy effects. We include a solution to
the mu-problem, and the prediction of observable effects at HERA. The models
also nicely allow for GUT-scale baryogenesis and R-parity violation without the
sphaleron interactions erasing the baryon-asymmetry.Comment: 6 pages, latex, no figures. Talk presented at SUSY-95. Work done in
collaboration with A. Chamseddin
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