56,850 research outputs found
Enhanced di-Higgs Production through Light Colored Scalars
We demonstrate enhanced di-Higgs production at the LHC in the presence of
modifications of the effective couplings of Higgs to gluons from new, light,
colored scalars. While our results apply to an arbitrary set of colored
scalars, we illustrate the effects with a real color octet scalar -- a simple,
experimentally viable model involving a light (~125-300 GeV) colored scalar.
Given the recent LHC results, we consider two distinct scenarios: First, if the
Higgs is indeed near 125 GeV, we show that the di-Higgs cross section could be
up to nearly one thousand times the Standard Model rate for particular octet
couplings and masses. This is potentially observable in \emph{single} Higgs
production modes, such as as well as where a small fraction of the
or events near the putative Higgs invariant mass peak contain
also a resonance consistent with the Higgs mass. Second, if the
Higgs is not at 125 GeV (and what the LHC has observed is an impostor), we show
that the same parameter region where singly-produced Higgs production can be
suppressed below current LHC limits, for a heavier Higgs mass, also
simultaneously predicts substantially enhanced di-Higgs production. We point
out several characteristic signals of di-Higgs production with a heavier Higgs
boson, such as , which could use same-sign
dileptons or trileptons plus missing energy to uncover evidence.Comment: 13 pages, 8 figure
Financial work incentives in Britain: comparisons over time and between family types
This paper reviews various techniques for quantifying financial incentives to work, shows how financial work incentives have changed across the population since 1979, and estimates how much of these changes are due to changes in the tax and benefit system
Skyrme models and nuclear matter equation of state
We investigate the role of pressure in a class of generalised Skyrme models. We introduce pressure as the trace of the spatial part of the energy-momentum tensor and show that it obeys the usual thermodynamical relation. Then, we compute analytically the mean-field equation of state in the high and medium pressure regimes by applying topological bounds on compact domains. The equation of state is further investigated numerically for the charge one skyrmions. We identify which term in a generalised Skyrme model is responsible for which part in the equation of state. Further, we compare our findings with the corresponding results in the Walecka model
Off-Mass-Shell N Scattering and
We adapt the off-shell N amplitude of the Tucson-Melbourne three-body
force to the half-off-shell amplitude of the pion rescattering contribution to
near threshold. This {\em pion} rescattering contribution,
together with the impulse term, provides a good description of the data when
the half-off-shell amplitude is linked to the phenomenological invariant
amplitudes obtained from meson factory N scattering data.Comment: 3 pages, contributed to STORRI99, Bloomington, Indiana, September
199
Radial vibrations of BPS skyrmions
We study radial vibrations of spherically symmetric skyrmions in the BPS
Skyrme model. Concretely, we numerically solve the linearised field equations
for small fluctuations in a skyrmion background, both for linearly stable
oscillations and for (unstable) resonances. This is complemented by numerical
solutions of the full nonlinear system, which confirm all the results of the
linear analysis. In all cases, the resulting fundamental excitation provides a
rather accurate value for the Roper resonance, supporting the hypothesis that
the BPS Skyrme model already gives a reasonable approximate description of this
resonance. Further, for many potentials additional higher resonances appear,
again in agreement with known experimental results.Comment: Latex, 41 pages, 22 pdf figures; v2: minor change
Normal mere exposure effect with impaired recognition in Alzheimer’s disease.
We investigated the mere exposure effect and the explicit memory in Alzheimer’s disease (AD) patients and elderly control subjects, using unfamiliar faces. During the exposure phase, the subjects estimated the age of briefly flashed faces. The mere exposure effect was examined by presenting pairs of faces (old and new) and asking participants to select the face they liked. The participants were then presented with a forced-choice explicit recognition task. Controls subjects exhibited above-chance preference and recognition scores for old faces. The AD patients also showed the mere exposure effect but no explicit recognition. These results suggest that the processes involved in the mere exposure effect are preserved in AD patients despite their impaired explicit recognition. The results are discussed in terms of Seamon et al.’s proposal (1995) that processes involved in the mere exposure effect are equivalent to those subserving perceptual priming. These processes would depend on extrastriate areas which are relatively preserved in AD patients
Model-robust regression and a Bayesian ``sandwich'' estimator
We present a new Bayesian approach to model-robust linear regression that
leads to uncertainty estimates with the same robustness properties as the
Huber--White sandwich estimator. The sandwich estimator is known to provide
asymptotically correct frequentist inference, even when standard modeling
assumptions such as linearity and homoscedasticity in the data-generating
mechanism are violated. Our derivation provides a compelling Bayesian
justification for using this simple and popular tool, and it also clarifies
what is being estimated when the data-generating mechanism is not linear. We
demonstrate the applicability of our approach using a simulation study and
health care cost data from an evaluation of the Washington State Basic Health
Plan.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS362 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Roper resonances and quasi-normal modes of Skyrmions
Radial vibrations of charge one hedgehog Skyrmions in the full Skyrme model
are analysed. We investigate how the properties of the lowest resonance modes
(quasi normal modes) - their frequencies and widths - depend on the form of the
potential (value of the pion mass as well as the addition of further
potentials) and on the inclusion of the sextic term. Then we consider the
inverse problem, where certain values for the frequencies and widths are
imposed, and the field theoretic Skyrme model potential giving rise to them is
reconstructed. This latter method allows to reproduce the physical Roper
resonances, as well as further physical properties of nucleons, with high
precision.Comment: LaTex, 24 pages, 18 figure
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