4,537 research outputs found
The LHC Discovery Potential of a Leptophilic Higgs
In this work, we examine a two-Higgs-doublet extension of the Standard Model
in which one Higgs doublet is responsible for giving mass to both up- and
down-type quarks, while a separate doublet is responsible for giving mass to
leptons. We examine both the theoretical and experimental constraints on the
model and show that large regions of parameter space are allowed by these
constraints in which the effective couplings between the lightest neutral Higgs
scalar and the Standard-Model leptons are substantially enhanced. We
investigate the collider phenomenology of such a "leptophilic"
two-Higgs-doublet model and show that in cases where the low-energy spectrum
contains only one light, CP-even scalar, a variety of collider processes
essentially irrelevant for the discovery of a Standard Model Higgs boson
(specifically those in which the Higgs boson decays directly into a
charged-lepton pair) can contribute significantly to the discovery potential of
a light-to-intermediate-mass (m_h < 140 GeV) Higgs boson at the LHC.Comment: 25 pages, LaVTeX, 11 figures, 1 tabl
Wandering Black Holes in Bright Disk Galaxy Halos
We perform SPH+N-body cosmological simulations of massive disk galaxies,
including a formalism for black hole seed formation and growth, and find that
satellite galaxies containing supermassive black hole seeds are often stripped
as they merge with the primary galaxy. These events naturally create a
population of "wandering" black holes that are the remnants of stripped
satellite cores; galaxies like the Milky Way may host 5 -- 15 of these objects
within their halos. The satellites that harbor black hole seeds are comparable
to Local Group dwarf galaxies such as the Small and Large Magellanic Clouds;
these galaxies are promising candidates to host nearby intermediate mass black
holes. Provided that these wandering black holes retain a gaseous accretion
disk from their host dwarf galaxy, they give a physical explanation for the
origin and observed properties of some recently discovered off-nuclear
ultraluminous X-ray sources such as HLX-1.Comment: Accepted for publication in ApJ Letter
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Induced oscillatory signaling in the beta frequency of top-down pain modulation
Background: Induced synchronized brain activity, particularly in the beta-frequency range, has rarely been investigated in human
electrophysiological studies of attentional modulation of the perception of nociceptive stimuli.
Methods: We measured time-resolved brain responses to nociceptive stimuli in healthy subjects (final data set: n 5 17) using
magnetoencephalography (MEG). In addition to investigating evoked responses as previous studies, we tested whether
synchronized beta activity induced by nociceptive stimuli differs between 2 attentional conditions. Subjects were presented
simultaneously with 2 stimulus modalities (pain-producing intraepidermal electrical stimuli and visual stimuli) in 2 different
experimental conditions, ie, âattention to painâ and âattention to color.â Pain ratings between conditions were compared using a 2-
sided paired-sample t test; MEG data were analyzed with Brainstorm.
Results: Pain ratings were significantly higher in the âattention to painâ compared with the âattention to colorâ condition. Peak
amplitudes of the evoked responses were significantly larger in the âattention to painâ condition bilaterally in the insula and
secondary somatosensory cortex, and in the primary somatosensory cortex (SI) contralateral to stimulation. Induced responses to
painful stimuli were significantly stronger in contralateral SI in the beta-frequency range in the âattention to painâ condition.
Conclusions: This study replicates previous reports w.r.t. the attentional modulation of evoked responses and suggests
a functional role of induced oscillatory activity in the beta frequency in top-down modulation of nociceptive stimuli
Induced Chiral Supergravities in 2D
We analyze actions for 2D supergravities induced by chiral conformal
supermatter. The latter may be thought as described at the classical level by
superspace actions invariant under super-reparametrization, super-Weyl and
super-Lorentz transformations. Upon quantization various anomalies appear which
characterize the non-trivial induced actions for the supergravitational sector.
We derive these induced actions using a chiral boson to represent the chiral
inducing matter. We show that they can be defined in a super-reparametrization
invariant way, but with super-Weyl and super-Lorentz anomalies. We consider the
case of and supergravities by working in their respective
superspace formulations and investigate their quantization in the conformal
gauge. The actions we consider arise naturally in off-critical heterotic and
spinning strings. In the conformal gauge, they correspond to chiral extensions
of the super-Liouville theory.Comment: 28 pages, TeX, (improved text, unchanged conclusions), USITP-93-0
Effective d=2 supersymmetric Lagrangians from d=1 supermatrix models
We discuss supersymmetric matrix models and exhibit the
associated collective field theory in the limit of dense eigenvalues.
From this theory we construct, by the addition of several new fields, a
supersymmetric effective field theory, which reduces to the collective field
theory when the new fields are replaced with their vacuum expectation values.
This effective theory is Poincare invariant and contains perturbative and
non-perturbative information about the associated superstrings. We exhibit
instanton solutions corresponding to the motion of single eigenvalues and
discuss their possible role in supersymmetry breaking.Comment: 59 pages. Contains 5 postscript figures included with epsf macro.
Figures obtained upon request, preprint CERN-TH.7017/9
Correlation between Fermi surface transformations and superconductivity in the electron-doped high- superconductor NdCeCuO
Two critical points have been revealed in the normal-state phase diagram of
the electron-doped cuprate superconductor NdCeCuO by exploring
the Fermi surface properties of high quality single crystals by high-field
magnetotransport. First, the quantitative analysis of the Shubnikov-de Haas
effect shows that the weak superlattice potential responsible for the Fermi
surface reconstruction in the overdoped regime extrapolates to zero at the
doping level corresponding to the onset of superconductivity.
Second, the high-field Hall coefficient exhibits a sharp drop right below
optimal doping where the superconducting transition
temperature is maximum. This drop is most likely caused by the onset of
long-range antiferromagnetic ordering. Thus, the superconducting dome appears
to be pinned by two critical points to the normal state phase diagram.Comment: 9 pages; 7 figures; 1 tabl
Instrumentation for Millimeter-wave Magnetoelectrodynamic Investigations of Low-Dimensional Conductors and Superconductors
We describe instrumentation for conducting high sensitivity millimeter-wave
cavity perturbation measurements over a broad frequency range (40-200 GHz) and
in the presence of strong magnetic fields (up to 33 tesla). A Millimeter-wave
Vector Network Analyzer (MVNA) acts as a continuously tunable microwave source
and phase sensitive detector (8-350 GHz), enabling simultaneous measurements of
the complex cavity parameters (resonance frequency and Q-value) at a rapid
repetition rate (approx. 10 kHz). We discuss the principal of operation of the
MVNA and the construction of a probe for coupling the MVNA to various
cylindrical resonator configurations which can easily be inserted into a high
field magnet cryostat. We also present several experimental results which
demonstrate the potential of the instrument for studies of low-dimensional
conducting systems.Comment: 20 pages including fig
Anesthetic management for neonate with giant cystic hygroma involved upper airway -A case report-
Significant differences exist between neonatal and adult airways. Anesthetic management of the airway may be challenging in neonate and young infant with large neck mass because these patients are at risk for sudden complete airway occlusion resulting in hypoventilation and hypoxemia. We experienced a 30-day-old baby presented with large cystic hygroma on the left side of neck. This mass was infiltrated in pharynx and large enough to disturb swallowing and breathing, and was not reduced despite of sclero-therapy. Therefore he was decided to get surgical removal. During the gaseous induction with sevoflurane, spontaneous respiration was maintained because difficulty was encountered with intubation. Intraoperatively, the endotracheal tube was dislodged unexpectedly because vigorous surgical traction. Postoperatively the baby was extubated 2 day after operation, and suffered from transient facial nerve palsy and continuous discharge from surgical wound. He was administered ICU for a long time
The Heterotic Green-Schwarz Superstring on an N=(2,0) Super-Worldsheet
By defining the heterotic Green-Schwarz superstring action on an N=(2,0)
super-worldsheet, rather than on an ordinary worldsheet, many problems with the
interacting Green-Schwarz superstring formalism can be solved. In the
light-cone approach, superconformally transforming the light-cone
super-worldsheet onto an N=(2,0) super-Riemann surface allows the elimination
of the non-trivial interaction-point operators that complicate the evaluation
of scattering amplitudes. In the Polyakov approach, the ten-dimensional
heterotic Green-Schwarz covariant action defined on an N=(2,0) super-worldsheet
can be gauge-fixed to a free-field action with non-anomalous N=(2,0)
superconformal invariance, and integrating the exponential of the covariant
action over all punctured N=(2,0) super-Riemann surfaces produces scattering
amplitudes that closely resemble amplitudes obtained using the unitary
light-cone approach.Comment: 33 page
Super Weyl invariance: BPS equations from heterotic worldsheets
It is well-known that the beta functions on a string worldsheet correspond to
the target space equations of motion, e.g. the Einstein equations. We show that
the BPS equations, i.e. the conditions of vanishing supersymmetry variations of
the space-time fermions, can be directly derived from the worldsheet. To this
end we consider the RNS-formulation of the heterotic string with (2,0)
supersymmetry, which describes a complex torsion target space that supports a
holomorphic vector bundle. After a detailed account of its quantization and
renormalization, we establish that the cancellation of the Weyl anomaly
combined with (2,0) finiteness implies the heterotic BPS conditions: At the one
loop level the geometry is required to be conformally balanced and the gauge
background has to satisfy the Hermitean Yang-Mills equations.Comment: 1+31 pages LaTeX, 5 figures; final version, discussion relation Weyl
invariance and (2,0) finiteness extended, typos correcte
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