1,030 research outputs found
The Effect of the State Children's Health Insurance Program on Health Insurance Coverage
This paper presents the first national estimates of the effects of the SCHIP expansions on insurance coverage. Using CPS data on insurance coverage during the years 1996 through 2000, we estimate two-stage least squares regressions of insurance coverage. We find that SCHIP had a small, but statistically significant positive effect on insurance coverage. Our regression results imply that between 4% and 10% of children meeting income eligibility standards for the new program gained public insurance. While low, these estimates indicate that states were more successful in enrolling children in SCHIP than they were with prior Medicaid expansions focused on children just above the poverty line. Crowd-out of private health insurance was estimated to be in line with estimates for the Medicaid expansions of the early 1990s, between 18% and 50%.
The impact of the ATLAS zero-lepton, jets and missing momentum search on a CMSSM fit
Recent ATLAS data significantly extend the exclusion limits for
supersymmetric particles. We examine the impact of such data on global fits of
the constrained minimal supersymmetric standard model (CMSSM) to indirect and
cosmological data. We calculate the likelihood map of the ATLAS search, taking
into account systematic errors on the signal and on the background. We validate
our calculation against the ATLAS determinaton of 95% confidence level
exclusion contours. A previous CMSSM global fit is then re-weighted by the
likelihood map, which takes a bite at the high probability density region of
the global fit, pushing scalar and gaugino masses up.Comment: 16 pages, 7 figures. v2 has bigger figures and fixed typos. v3 has
clarified explanation of our handling of signal systematic
Curvature-induced phase transitions in the inflationary universe - Supersymmetric Nambu-Jona-Lasinio Model in de Sitter spacetime -
The phase structure associated with the chiral symmetry is thoroughly
investigated in de Sitter spacetime in the supersymmetric Nambu-Jona-Lasinio
model with supersymmetry breaking terms. The argument is given in the three and
four space-time dimensions in the leading order of the 1/N expansion and it is
shown that the phase characteristics of the chiral symmetry is determined by
the curvature of de Sitter spacetime. It is found that the symmetry breaking
takes place as the first order as well as second order phase transition
depending on the choice of the coupling constant and the parameter associated
with the supersymmetry breaking term. The critical curves expressing the phase
boundary are obtained. We also discuss the model in the context of the chaotic
inflation scenario where topological defects (cosmic strings) develop during
the inflation.Comment: 29 pages, 6 figures, REVTe
Implications of the 125 GeV Higgs boson for scalar dark matter and for the CMSSM phenomenology
We study phenomenological implications of the ATLAS and CMS hint of a GeV Higgs boson for the singlet, and singlet plus doublet non-supersymmetric
dark matter models, and for the phenomenology of the CMSSM. We show that in
scalar dark matter models the vacuum stability bound on Higgs boson mass is
lower than in the standard model and the 125 GeV Higgs boson is consistent with
the models being valid up the GUT or Planck scale. We perform a detailed study
of the full CMSSM parameter space keeping the Higgs boson mass fixed to GeV, and study in detail the freeze-out processes that imply the observed
amount of dark matter. After imposing all phenomenological constraints except
for the muon we show that the CMSSM parameter space is divided
into well separated regions with distinctive but in general heavy sparticle
mass spectra. Imposing the constraint introduces severe tension
between the high SUSY scale and the experimental measurements -- only the
slepton co-annihilation region survives with potentially testable sparticle
masses at the LHC. In the latter case the spin-independent DM-nucleon
scattering cross section is predicted to be below detectable limit at the
XENON100 but might be of measurable magnitude in the general case of light dark
matter with large bino-higgsino mixing and unobservably large scalar masses.Comment: 17 pages, 7 figures. v3: same as published versio
Prospects for Discovering Supersymmetry at the LHC
Supersymmetry is one of the best-motivated candidates for physics beyond the
Standard Model that might be discovered at the LHC. There are many reasons to
expect that it may appear at the TeV scale, in particular because it provides a
natural cold dark matter candidate. The apparent discrepancy between the
experimental measurement of g_mu - 2 and the Standard model value calculated
using low-energy e+ e- data favours relatively light sparticles accessible to
the LHC. A global likelihood analysis including this, other electroweak
precision observables and B-decay observables suggests that the LHC might be
able to discover supersymmetry with 1/fb or less of integrated luminosity. The
LHC should be able to discover supersymmetry via the classic missing-energy
signature, or in alternative phenomenological scenarios. The prospects for
discovering supersymmetry at the LHC look very good.Comment: 8 pages, 11 figure
Probing CP Violation with and without Momentum Reconstruction at the LHC
We study the potential to observe CP-violating effects in SUSY cascade decay
chains at the LHC. We consider squark and gluino production followed by
subsequent decays into neutralinos with a three-body leptonic decay in the
final step. Asymmetries composed by triple products of momenta of the final
state particles are sensitive to CP-violating effects. Due to large boosts
these asymmetries can be difficult to observe at a hadron collider. We show
that using all available kinematic information one can reconstruct the decay
chains on an event-by-event basis even in the case of 3-body decays, neutrinos
and LSPs in the final state. We also discuss the most important experimental
effects like major backgrounds and momentum smearing due to finite detector
resolution. We show that with 300 fb of collected data, CP violation may
be discovered at the LHC for a wide range of the phase of the bino mass
parameter .Comment: Version accepted for publication in JHEP. Clarifications added on the
assumptions used for plots. New references adde
A Two-Tiered Correlation of Dark Matter with Missing Transverse Energy: Reconstructing the Lightest Supersymmetric Particle Mass at the LHC
We suggest that non-trivial correlations between the dark matter particle
mass and collider based probes of missing transverse energy H_T^miss may
facilitate a two tiered approach to the initial discovery of supersymmetry and
the subsequent reconstruction of the LSP mass at the LHC. These correlations
are demonstrated via extensive Monte Carlo simulation of seventeen benchmark
models, each sampled at five distinct LHC center-of-mass beam energies,
spanning the parameter space of No-Scale F-SU(5).This construction is defined
in turn by the union of the Flipped SU(5) Grand Unified Theory, two pairs of
hypothetical TeV scale vector-like supersymmetric multiplets with origins in
F-theory, and the dynamically established boundary conditions of No-Scale
Supergravity. In addition, we consider a control sample comprised of a standard
minimal Supergravity benchmark point. Led by a striking similarity between the
H_T^miss distribution and the familiar power spectrum of a black body radiator
at various temperatures, we implement a broad empirical fit of our simulation
against a Poisson distribution ansatz. We advance the resulting fit as a
theoretical blueprint for deducing the mass of the LSP, utilizing only the
missing transverse energy in a statistical sampling of >= 9 jet events.
Cumulative uncertainties central to the method subsist at a satisfactory 12-15%
level. The fact that supersymmetric particle spectrum of No-Scale F-SU(5) has
thrived the withering onslaught of early LHC data that is steadily decimating
the Constrained Minimal Supersymmetric Standard Model and minimal Supergravity
parameter spaces is a prime motivation for augmenting more conventional LSP
search methodologies with the presently proposed alternative.Comment: JHEP version, 17 pages, 9 Figures, 2 Table
Statistical Properties of Charmonium Spectrum and a New Mechanism of J/\psi Suppression
The statistical properties of Charmonium energy spectrum determined by the
Bethe-Salpeter equation are investigated. It is found that the regular motion
of the system can be expected at a small value of color screening
mass but the chaotic motion at a large one. It is shown that the level mixing
due to color screening serves as a new mechanism resulting in the J/
suppression. Moreover, this kind of suppression can occur before the color
screening mass reaches its critical value for J/ dissociation. It implies
that a strong J/ suppression is possible in the absence of dissociation
of J/.Comment: 13 latex pages, 2 figures. Phys. Rev. C in pres
Constraints on Supersymmetry from Relic Density compared with future Higgs Searches at the LHC
Among the theories beyond the Standard Model (SM) of particle physics
Supersymmetry (SUSY) provides an excellent dark matter (DM) candidate, the
neutralino. One clear prediction of cosmology is the annihilation cross section
of DM particles, assuming them to be a thermal relic from the early universe.
In most of the parameter space of Supersymmetry the annihilation cross section
is too small compared with the prediction of cosmology. However, for large
values of the tan beta parameter the annihilation through s-channel
pseudoscalar Higgs exchange yields the correct relic density in practically the
whole range of possible SUSY masses up to the few TeV range. The required
values of tan beta are typically around 50, i.e. of the order of top and bottom
mass ratio, which happens to be also the range allowing for Yukawa unification
in a Grand Unified Theory with gauge coupling unification. For such large
values of tan beta the associated production of the heavier Higgses, which is
enhanced by tan beta squared, becomes three orders of magnitude larger than the
production of a simlar SM-like Higgs and could be observable as one of the
first hints of new physics at the LHC.Comment: 12 pages, 5 figures, Published version in Phys. Lett. B with updated
references and minor correction
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