221 research outputs found
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
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
Megasatellites: a peculiar class of giant minisatellites in genes involved in cell adhesion and pathogenicity in Candida glabrata
Minisatellites are DNA tandem repeats that are found in all sequenced genomes. In the yeast Saccharomyces cerevisiae, they are frequently encountered in genes encoding cell wall proteins. Minisatellites present in the completely sequenced genome of the pathogenic yeast Candida glabrata were similarly analyzed, and two new types of minisatellites were discovered: minisatellites that are composed of two different intermingled repeats (called compound minisatellites), and minisatellites containing unusually long repeated motifs (126–429 bp). These long repeat minisatellites may reach unusual length for such elements (up to 10 kb). Due to these peculiar properties, they have been named ‘megasatellites’. They are found essentially in genes involved in cell–cell adhesion, and could therefore be involved in the ability of this opportunistic pathogen to colonize the human host. In addition to megasatellites, found in large paralogous gene families, there are 93 minisatellites with simple shorter motifs, comparable to those found in S. cerevisiae. Most of the time, these minisatellites are not conserved between C. glabrata and S. cerevisiae, although their host genes are well conserved, raising the question of an active mechanism creating minisatellites de novo in hemiascomycetes
Naturalness and superpartner masses or when to give up on weak scale supersymmetry
Superpartner masses cannot be arbitrarily heavy if supersymmetric extensions
of the standard model explain the stability of the gauge hierarchy. This
ancient and hallowed motivation for weak scale supersymmetry is often quoted,
yet no reliable determination of this upper limit on superpartner masses
exists. In this paper we compute upper bounds on superpartner masses in the
minimal supersymmetric model, and we identify which values of the superpartner
masses correspond to the most natural explanation of the hierarchy stability.
We compare the most natural value of these masses and their upper limits to the
physics reach of current and future colliders. As a result, we find that
supersymmetry could explain weak scale stability naturally even if no
superpartners are discovered at LEP II or the Tevatron (even with the Main
Injector upgrade). However, we find that supersymmetry cannot provide a
complete explanation of weak scale stability, if squarks and gluinos have
masses beyond the physics reach of the LHC. Moreover, in the most natural
scenarios, many sparticles, for example, charginos, squarks, and gluinos, lie
within the physics reach of either LEP II or the Tevatron. Our analysis
determines the most natural value of the chargino (squark) ((gluino)) mass
consistent with current experimental constraints is 50 (250) ((250)) GeV
and the corresponding theoretical upper bound is 250 (700) ((800)) GeV.Comment: 14 pages, LaTex, 17 figures uuencoded, gz-compressed file. Minor
revisions bring archived manuscript in line with the published versio
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
Left ventricular apical diseases
There are many disorders that may involve the left ventricular (LV) apex; however, they are sometimes difficult to differentiate. In this setting cardiac imaging methods can provide the clue to obtaining the diagnosis. The purpose of this review is to illustrate the spectrum of diseases that most frequently affect the apex of the LV including Tako-Tsubo cardiomyopathy, LV aneurysms and pseudoaneurysms, apical diverticula, apical ventricular remodelling, apical hypertrophic cardiomyopathy, LV non-compaction, arrhythmogenic right ventricular dysplasia with LV involvement and LV false tendons, with an emphasis on the diagnostic criteria and imaging features
Tevatron and LEP-II Probes of Minimal and String-Motivated Supergravity Models
We explore the ability of the Tevatron to probe Minimal Supersymmetry with
high energy scale boundary conditions motivated by supersymmetry breaking in
the context of supergravity/superstring theory. A number of boundary condition
possibilities are considered: dilaton-like string boundary conditions applied
at the standard GUT unification scale or alternatively at the string scale; and
extreme (``no-scale'') minimal supergravity boundary conditions imposed at the
GUT scale or string scale. For numerous specific cases within each scenario the
sparticle spectra are computed and then fed into ISAJET 7.07 so that explicit
signatures can be examined in detail. We find that, for some of the boundary
condition choices, large regions of parameter space can be explored via
same-sign dilepton and isolated trilepton signals. For other choices, the mass
reach of Tevatron collider experiments is much more limited. We also compare
mass reach of Tevatron experiments with the corresponding reach at LEP 200.Comment: 44 pages, requires phyzzx.tex, tables.tex, full postscript file
including embedded figures available via anonymous ftp at ucdhep.ucdavis.edu
as [anonymous.gunion]bgkp.ps, preprint UCD-94-1
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