7,688 research outputs found
Complex Scalar Singlet Dark Matter: Vacuum Stability and Phenomenology
We analyze one-loop vacuum stability, perturbativity, and phenomenological
constraints on a complex singlet extension of the Standard Model (SM) scalar
sector containing a scalar dark matter candidate. We study vacuum stability
considerations using a gauge-invariant approach and compare with the
conventional gauge-dependent procedure. We show that, if new physics exists at
the TeV scale, the vacuum stability analysis and experimental constraints from
the dark matter sector, electroweak precision data, and LEP allow both a
Higgs-like scalar in the mass range allowed by the latest results from CMS and
ATLAS and a lighter singlet-like scalar with weak couplings to SM particles. If
instead no new physics appears until higher energy scales, there may be
significant tension between the vacuum stability analysis and phenomenological
constraints (in particular electroweak precision data) to the extent that the
complex singlet extension with light Higgs and singlet masses would be ruled
out. We comment on the possible implications of a scalar with ~125 GeV mass and
future ATLAS invisible decay searches.Comment: 24 pages, 12 figures; v2 - fixed minor typos, added reference,
changed layou
Disseminated eruptive giant mollusca contagiosa in an adult psoriasis patient during efalizumab therapy
Molluscum contagiosum is a common viral skin infection in children with atopic diathesis and not rare in HIV patients. We report a 45-year-old psoriasis patient who developed eruptive mollusca contagiosa during an antipsoriatic treatment with efalizumab. Copyright (C) 2008 S. Karger AG, Basel
Photoluminescence modification by high-order photonic band with abnormal dispersion in ZnO inverse opal
We measured the angle- and polarization-resolved reflection and
photoluminescence spectra of ZnO inverse opals. Significant enhancement of
spontaneous emission is observed. The enhanced emission not only has good
directionality but also can be linearly polarized. A detailed theoretical
analysis and numerical simulation reveal that such enhancement is caused by the
abnormal dispersion of a high-order photonic band. The frozen mode at a
stationary inflection point of a dispersion curve can strongly modify the
intensity, directionality and polarization of spontaneous emission.Comment: 22 pages, 11 figures, figures modified, references added, more
explanation adde
Adaptive User Interface for a Camera Aperture within an Active Display Area
This publication describes systems and techniques to account for an active display area around a camera aperture in a “hole-punch” style display of an electronic device to reduce a light-leaking effect caused by pixels surrounding the camera aperture. Illuminated pixels that are proximate to the camera aperture can degrade a quality of an image captured by a camera sensor by preventing the sensor from properly detecting light from a targeted image, such as a user’s face. To counteract this image degradation, techniques described herein override the illumination control for pixels surrounding the hole in the display. For example, responsive to the camera being engaged, one or more rings of pixels around the display hole can be controlled to have a decreased illumination level based on ambient brightness. The decreased illumination can involve being commanded to be turned off or being commanded to illuminate at a lower level. With less light emanating from pixels that are proximate to the display hole, there is less light pollution funneled into the camera aperture to affect the camera sensor
Sparse tree search optimality guarantees in POMDPs with continuous observation spaces
Partially observable Markov decision processes (POMDPs) with continuous state
and observation spaces have powerful flexibility for representing real-world
decision and control problems but are notoriously difficult to solve. Recent
online sampling-based algorithms that use observation likelihood weighting have
shown unprecedented effectiveness in domains with continuous observation
spaces. However there has been no formal theoretical justification for this
technique. This work offers such a justification, proving that a simplified
algorithm, partially observable weighted sparse sampling (POWSS), will estimate
Q-values accurately with high probability and can be made to perform
arbitrarily near the optimal solution by increasing computational power
Centimeter-wave continuum radiation from the rho Ophiuchi molecular cloud
The rho Oph molecular cloud is undergoing intermediate-mass star formation.
UV radiation from its hottest young stars heats and dissociates exposed layers,
but does not ionize hydrogen. Only faint radiation from the Rayleigh-Jeans tail
of ~10-100K dust is expected at wavelengths longwards of 3mm. Yet Cosmic
Background Imager (CBI) observations reveal that the rho Oph W
photo-dissociation region (PDR) is surprisingly bright at centimetre
wavelengths. We searched for interpretations consistent with the WMAP radio
spectrum, new ISO-LWS parallel mode images and archival Spitzer data.
Dust-related emission mechanisms at 1 cm, as proposed by Draine & Lazarian, are
a possibility. But a magnetic enhancement of the grain opacity at 1cm is
inconsistent with the morphology of the dust column maps Nd and the lack of
detected polarization. Spinning dust, or electric-dipole radiation from
spinning very small grains (VSGs), comfortably explains the radio spectrum,
although not the conspicuous absence from the CBI data of the infrared
circumstellar nebulae around the B-type stars S1 and SR~3. Allowing for VSG
depletion can marginally reconcile spinning dust with the data. As an
alternative interpretation we consider the continuum from residual charges in
rho Oph W, where most of carbon should be photoionised by the close binary
HD147889 (B2IV, B3IV). Electron densities of ~100 cm^{-3}, or H-nucleus
densities n_H > 1E6 cm^{-3}, are required to interpret rho Oph W as the CII
Stromgren sphere of HD147889. However the observed steep and positive
low-frequency spectral index would then require optically thick emission from
an hitherto unobserved ensemble of dense clumps or sheets with a filling factor
~1E-4 and n_H ~ 1E7 cm^{-3}.Comment: accepted for publication in MNRA
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