7,323 research outputs found
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
Argentina's default and the lack of dire consequences
We analyze the 2001 Argentine default on its foreign debt and its consequences in terms of the existing literature on sovereign debt default. It is our purpose to evaluate this experience and to see to what extent the Argentine case requires a re-thinking on the nature and consequences of defaults. We show that the Argentine case contradicts many of their standard predictions, in particular its posterior lack of access to international credit, restriction to international trade and negative economic growth. Moreover, it corroborates the historical fact that many defaulters “get away with it.
Combustion chemistry of solid propellants
Several studies are described of the chemistry of solid propellant combustion which employed a fast-scanning optical spectrometer. Expanded abstracts are presented for four of the studies which were previously reported. One study of the ignition of composite propellants yielded data which suggested early ammonium perchlorate decomposition and reaction. The results of a study of the spatial distribution of molecular species in flames from uncatalyzed and copper or lead catalyzed double-based propellants support previously published conclusions concerning the site of action of these metal catalysts. A study of the ammonium-perchlorate-polymeric-fuel-binder reaction in thin films, made by use of infrared absorption spectrometry, yielded a characterization of a rapid condensed-phase reaction which is likely important during the ignition transient and the burning process
Study of high resolution wind measuring systems. phase i survey, july through september 1964
High resolution wind measuring systems using probes, tracers, and sound technique
Debt as a control device in transitional economies : the experiences of Hungary and Poland
The basic economic challenge in the transition from socialism to capitalism is creating incentive structures and institutions that promote enterprise change and restructuring. This is the motivation for most of the reforms debated during the transition - whether privatization, demonopolization, trade reform, or financial sector reform. Most research on corporate governance and privatization has focused on the role of owners - whether on the problems inherent in the separation of ownership and management (most Western literature) or on the need for true owners who represents the interests of capital (most literature on transition economies). But debt is also an important control device, as Western literature on corporate finance increasingly recognizes. The authors explore debt's role as a control device in transition economies, focusing especially on Hungary and Poland, which are relatively far along in the reform process. They ask, first, in what ways creditors exert control over firms in advanced market economies and how such control interacts with that exerted by equity holders. They then ask whether creditors in Central and Eastern European countries play similar roles and, if not, what roles they should play, and what can be done to give them the capacity and incentives to play those roles. They focus on three fundamental requirements for debt to function as a control device: information, proper incentives for creditors (including banks, suppliers, and government), and an efficient legal framework for debt collection (including collateral, workout, and bankruptcy regimes). While both countries are making progress in all three areas, there is still much to be done. Hungary and Poland illustrate only two of many approaches. Other transitional economies, such as the Czech Republic, Estonia, and Russia, are following different approaches that should be explored in future analysis.International Terrorism&Counterterrorism,Banks&Banking Reform,Payment Systems&Infrastructure,Environmental Economics&Policies,Financial Intermediation,Banks&Banking Reform,Environmental Economics&Policies,Financial Intermediation,Financial Crisis Management&Restructuring,Housing Finance
The Zieschang-McCool method for generating algebraic mapping-class groups
Let g and p be non-negative integers.
Let A(g,p) denote the group consisting of all those automorphisms of the free
group on {t_1,...,t_p, x_1,...,x_g, y_1,...y_g} which fix the element
t_1t_2...t_p[x_1,y_1]...[x_g,y_g] and permute the set of conjugacy classes
{[t_1],....,[t_p]}. Labru\`ere and Paris, building on work of Artin, Magnus,
Dehn, Nielsen, Lickorish, Zieschang, Birman, Humphries, and others, showed that
A(g,p) is generated by a set that is called the ADLH set. We use methods of
Zieschang and McCool to give a self-contained, algebraic proof of this result.
Labru\`ere and Paris also gave defining relations for the ADLH set in A(g,p);
we do not know an algebraic proof of this for g > 1. Consider an orientable
surface S(g,p) of genus g with p punctures, such that (g,p) is not (0,0) or
(0,1). The algebraic mapping-class group of S(g,p), denoted M(g,p), is defined
as the group of all those outer automorphisms of the one-relator group with
generating set {t_1,...,t_p, x_1,...,x_g, y_1,...y_g} and relator
t_1t_2...t_p[x_1,y_1]...[x_g,y_g] which permute the set of conjugacy classes
{[t_1],....,[t_p]}. It now follows from a result of Nielsen that M(g,p) is
generated by the image of the ADLH set together with a reflection. This gives a
new way of seeing that M(g,p) equals the (topological) mapping-class group of
S(g,p), along lines suggested by Magnus, Karrass, and Solitar in 1966.Comment: 21 pages, 0 figure
Non-critical String Cosmologies
Non-critical String Cosmologies are offered as an alternative to Standard Big
Bang Cosmology. The new features encompassed within the dilaton dependent
non-critical terms affect the dynamics of the Universe\'s evolution in an
unconventional manner being in agreement with the cosmological data.
Non-criticality is responsible for a late transition to acceleration at
redshifts z=0.2. The role of the uncoupled rolling dilaton to relic abundance
calculations is discussed. The uncoupled rolling dilaton dilutes the neutralino
relic densities in supersymmetric theories by factors of ten, relaxing
considerably the severe WMAP Dark Matter constraints, while at the same time
leaves almost unaffected the baryon density in agreement with primordial
Nucleosynthesis.Comment: 16 pages, 7 figures, conference tal
Confronting Electroweak Fine-tuning with No-Scale Supergravity
Applying No-Scale Supergravity boundary conditions at a heavy unification
scale to the Flipped grand unified theory with extra TeV-scale
vector-like multiplets, No-Scale -, we express the
-boson mass as an explicit function of the boundary gaugino mass
, , with implicit dependence upon a
dimensionless ratio of the supersymmetric Higgs mixing parameter and
. Setting the top Yukawa coupling consistent with GeV at
GeV, the value of naturally tends toward , which
indirectly suggests underlying action of the Giudice-Masiero mechanism.
Proportional dependence of all model scales upon the unified gaugino mass
in the No-Scale - model suggests one possible
mechanism of confronting the electroweak fine tuning problem.Comment: Physics Letters B version; 8 Pages, 7 Figures, 1 Tabl
Ammonium-perchlorate diffusion flames - A spectrographic investigation
Spectroscopic analyses on ammonium perchlorate diffusion flames with various fuel
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
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