16,314 research outputs found
Lone Higgs at the LHC
We address the possible scenario that the Large Hadron Collider (LHC)
discovers only a Higgs boson after 10 fb^{-1} of operation, and attempt to
identify this Higgs boson as that of the Standard Model (SM), the minimal
universal extra dimension model (MUED), the littlest Higgs model with T-parity
(LHT), or the minimal supersymmetric Standard Model (MSSM), using only the
measurement of the product of gluon-fusion production cross section and the
di-photon branching ratio. In MUED, by decoupling any new physics sufficiently
to evade the discovery reach at the LHC, the deviation of the signal from the
SM is not statistically significant. However, in LHT and MSSM, it is possible
to have a significant deviation in the signal that is consistent with this
"lone Higgs scenario", and, in the case of a very large suppression, we can
distinguish MSSM and LHT before the discovery of any new resonances. Starting
with the lone Higgs scenario and the deviation in this measurement from the
Standard Model prediction (whether or not statistically significant), we offer
tests that may discriminate the models and search strategies of discovering new
physics signatures with increasing integrated luminosity.Comment: 32 pages, 25 figures, PRD versio
The Taiwan ECDFS Near-Infrared Survey: Ultra-deep J and Ks Imaging in the Extended Chandra Deep Field-South
We present ultra-deep J and Ks imaging observations covering a 30' * 30' area
of the Extended Chandra Deep Field-South (ECDFS) carried out by our Taiwan
ECDFS Near-Infrared Survey (TENIS). The median 5-sigma limiting magnitudes for
all detected objects in the ECDFS reach 24.5 and 23.9 mag (AB) for J and Ks,
respectively. In the inner 400 arcmin^2 region where the sensitivity is more
uniform, objects as faint as 25.6 and 25.0 mag are detected at 5-sigma. So this
is by far the deepest J and Ks datasets available for the ECDFS. To combine the
TENIS with the Spitzer IRAC data for obtaining better spectral energy
distributions of high-redshift objects, we developed a novel deconvolution
technique (IRACLEAN) to accurately estimate the IRAC fluxes. IRACLEAN can
minimize the effect of blending in the IRAC images caused by the large
point-spread functions and reduce the confusion noise. We applied IRACLEAN to
the images from the Spitzer IRAC/MUSYC Public Legacy in the ECDFS survey
(SIMPLE) and generated a J+Ks selected multi-wavelength catalog including the
photometry of both the TENIS near-infrared and the SIMPLE IRAC data. We
publicly release the data products derived from this work, including the J and
Ks images and the J+Ks selected multiwavelength catalog.Comment: 25 pages, 25 figures, ApJS in pres
Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout
As part of the government response to the Deepwater Horizon blowout, a Well Integrity Team evaluated the geologic hazards of shutting in the Macondo Well at the seafloor and determined the conditions under which it could safely be undertaken. Of particular concern was the possibility that, under the anticipated high shut-in pressures, oil could leak out of the well casing below the seafloor. Such a leak could lead to new geologic pathways for hydrocarbon release to the Gulf of Mexico. Evaluating this hazard required analyses of 2D and 3D seismic surveys, seafloor bathymetry, sediment properties, geophysical well logs, and drilling data to assess the geological, hydrological, and geomechanical conditions around the Macondo Well. After the well was successfully capped and shut in on July 15, 2010, a variety of monitoring activities were used to assess subsurface well integrity. These activities included acquisition of wellhead pressure data, marine multichannel seismic pro- files, seafloor and water-column sonar surveys, and wellhead visual/acoustic monitoring. These data showed that the Macondo Well was not leaking after shut in, and therefore, it could remain safely shut until reservoir pressures were suppressed (killed) with heavy drilling mud and the well was sealed with cement
Ground-based PIV and numerical flow visualization results from the surface tension driven convection experiment
The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the United States Microgravity Laboratory-1 (USML-1) Spacelab mission planned for June, 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electric, two dimensional Particle Image Velocimetry (PIV) technique called Particle Displacement Tracking (PDT), which uses a simple space domain particle tracking algorithm. Results using the ground based STDCE hardware, with a radiant flux heating mode, and the PDT system are compared to numerical solutions obtained by solving the axisymmetric Navier Stokes equations with a deformable free surface. The PDT technique is successful in producing a velocity vector field and corresponding stream function from the raw video data which satisfactorily represents the physical flow. A numerical program is used to compute the velocity field and corresponding stream function under identical conditions. Both the PDT system and numerical results were compared to a streak photograph, used as a benchmark, with good correlation
Far-infrared measurements of oxygen-doped polycrystalline La2CuO4.0315 superconductor under slow-cooled and fast-cooled conditions
We have studied the far-infrared (far-IR) charge dynamics of an equilibrated
pure oxygen doped La2CuO4+0.0315 under slow-cooled and fast-cooled conditions.
The superconducting transition temperature (Tc) for the slow-cooled and that
for the fast-cooled processes were respectively found to be close to the two
intrinsic Tc's: One at 30 K and the other at 15 K. Direct comparison with our
previous results and other far-IR and Raman studies on single crystalline
La2-xSrxCuO4, we conclude that the topology of the pristine electronic phases
that are responsible for the two intrinsic Tc's is holes arranged into
two-dimensional (2D) square lattices.Comment: Submitted to PR
SAO mission support software and data standards, version 1.0
This document defines the software developed by the SAO AXAF Mission Support (MS) Program and defines standards for the software development process and control of data products generated by the software. The SAO MS is tasked to develop and use software to perform a variety of functions in support of the AXAF mission. Software is developed by software engineers and scientists, and commercial off-the-shelf (COTS) software is used either directly or customized through the use of scripts to implement analysis procedures. Software controls real-time laboratory instruments, performs data archiving, displays data, and generates model predictions. Much software is used in the analysis of data to generate data products that are required by the AXAF project, for example, on-orbit mirror performance predictions or detailed characterization of the mirror reflection performance with energy
Effects of Kinks on DNA Elasticity
We study the elastic response of a worm-like polymer chain with reversible
kink-like structural defects. This is a generic model for (a) the
double-stranded DNA with sharp bends induced by binding of certain proteins,
and (b) effects of trans-gauche rotations in the backbone of the
single-stranded DNA. The problem is solved both analytically and numerically by
generalizing the well-known analogy to the Quantum Rotator. In the small
stretching force regime, we find that the persistence length is renormalized
due to the presence of the kinks. In the opposite regime, the response to the
strong stretching is determined solely by the bare persistence length with
exponential corrections due to the ``ideal gas of kinks''. This high-force
behavior changes significantly in the limit of high bending rigidity of the
chain. In that case, the leading corrections to the mechanical response are
likely to be due to the formation of multi-kink structures, such as kink pairs.Comment: v1: 16 pages, 7 figures, LaTeX; submitted to Physical Review E; v2: a
new subsection on soft kinks added to section Theory, sections Introduction
and Conclusions expanded, references added, other minor changes; v3: a
reference adde
- …