21,591 research outputs found
A Higgs Conundrum with Vector Fermions
Many models of Beyond the Standard Model physics involve heavy colored
fermions. We study models where the new fermions have vector interactions and
examine the connection between electroweak precision measurements and Higgs
production. In particular, for parameters which are allowed by precision
measurements, we show that the gluon fusion Higgs cross section and the Higgs
decay branching ratios must be close to those predicted by the Standard Model.
The models we discuss thus represent scenarios with new physics which will be
extremely difficult to distinguish from the minimal Standard Model. We pay
particular attention to the decoupling properties of the vector fermions.Comment: 34 pages, 15 figures. Version accepted for publication in Phys. Rev.
An integrated study of structures, aerodynamics and controls on the forward swept wing X-29A and the oblique wing research aircraft
The results of an integrated study of structures, aerodynamics, and controls using the STARS program on two advanced airplane configurations are presented. Results for the X-29A include finite element modeling, free vibration analyses, unsteady aerodynamic calculations, flutter/divergence analyses, and an aeroservoelastic controls analysis. Good correlation is shown between STARS results and various other verified results. The tasks performed on the Oblique Wing Research Aircraft include finite element modeling and free vibration analyses
Test results of JPL LiSOCl sub 2 cells
In the development of high rate Li-SO-Cl2 cells for various applications, the goal is to achieve 300 watt-hours per kilogram at the C/2 (5 amp) rate in a D cell configuration. The JPL role is to develop the understanding of the performance, life, and safety limiting characteristics in the cell and to transfer the technology to a manufacturer to produce a safe, high quality product in a reproducible manner. The approach taken to achieve the goals is divided into four subject areas: cathode processes and characteristics; chemical reactions and safety; cell design and assembly; and performance and abuse testing. The progress made in each of these areas is discussed
Automated patient monitoring system
Radio-linked patient monitoring system collects several channels of physiological data from as many as 64 hospital patients and transmits the data in digital form to a central control station. The system consists of a central control station and battery-operated patient units comprising small strap-on electronics packages
Technology development for 4k x 4k, back-illuminated, fully depleted scientific CCD imagers
Journal ArticleWe have developed scientific charge-coupled devices (CCDs) that are fabricated on high-resistivity, n-type silicon substrates, and have demonstrated fully depleted operation for substrate thicknesses of 200-675 ÎŒm with formats as large as 2048 Ă 4096 (15 ÎŒm pixels) and 3512 Ă 3512 (10.5 ÎŒm pixels). The main application area for these devices is space and ground-based astronomy, and the CCDs are operated at cryogenic temperatures with slow-scan readout for good performance in terms of dark current and noise. In this work we describe the technology development efforts needed to realize a 4k Ă 4k (15 ÎŒm pixel) CCD with a die area of (64 mm)2. In particular, we describe improved gettering techniques for low dark current and high charge transfer efficiency that have been developed in order to improve fabrication yields for these very large format CCDs
High-voltage-compatible fully depleted CCDs
Journal ArticleWe describe charge-coupled device (CCD) development activities at the Lawrence Berkeley National Laboratory (LBNL). Back-illuminated CCDs fabricated on 200-300 fxm thick, fully depleted, high-resistivity silicon substrates are produced in partnership with a commercial CCD foundry. The CCDs are fully depleted by the application of a substrate bias voltage. Spatial resolution considerations require operation of thick, fully depleted CCDs at high substrate bias voltages. We have developed CCDs that are compatible with substrate bias voltages of at least 200V. This improves spatial resolution for a given thickness, and allows for full depletion of thicker CCDs than previously considered. We have demonstrated full depletion of 650-675 iim thick CCDs, with potential applications in direct x-ray detection. In this work we discuss the issues related to high-voltage operation of fully depleted CCDs, as well as experimental results on high-voltage-compatible CCDs
Enhancement and evaluation of Skylab photography for potential land use inventories, part 1
The author has identified the following significant results. Three sites were evaluated for land use inventory: Finger Lakes - Tompkins County, Lower Hudson Valley - Newburgh, and Suffolk County - Long Island. Special photo enhancement processes were developed to standardize the density range and contrast among S190A negatives. Enhanced black and white enlargements were converted to color by contact printing onto diazo film. A color prediction model related the density values on each spectral band for each category of land use to the spectral properties of the various diazo dyes. The S190A multispectral system proved to be almost as effective as the S190B high resolution camera for inventorying land use. Aggregate error for Level 1 averaged about 12% while Level 2 aggregate error averaged about 25%. The S190A system proved to be much superior to LANDSAT in inventorying land use, primarily because of increased resolution
Exclusive Higgs Boson Production with bottom quarks at Hadron Colliders
We present the next-to-leading order QCD corrected rate for the production of
a scalar Higgs boson with a pair of high p_T bottom and anti-bottom quarks at
the Tevatron and at the Large Hadron Collider. Results are given for both the
Standard Model and the Minimal Supersymmetric Standard Model. The exclusive
b-bbar-h production rate is small in the Standard Model, but it can be greatly
enhanced in the Minimal Supersymmetric Standard Model for large tan(beta),
making b-bbar-h an important discovery mode. We find that the next-to-leading
order QCD results are much less sensitive to the renormalization and
factorization scales than the lowest order results, but have a significant
dependence on the choice of the renormalization scheme for the bottom quark
Yukawa coupling.Comment: 27 pages, 17 figures, RevTeX
The roots of "Western European societal evolution". A concept of Europe by JenĆ SzƱcs
JenĆ SzƱcs wrote his essay entitled Sketch on the three regions of Europe in the early 1980s in Hungary. During these years, a historically well-argued opinion emphasising a substantial difference between Central European and Eastern European societies was warmly received in various circles of the political opposition. In a wider European perspective SzƱcs used the old âliberty toposâ which claims that the history of Europe is no other than the fulfillment of liberty. In his Sketch, SzƱcs does not only concentrate on questions concerning the Middle Ages in Western Europe. Yet it is this stream of thought which brought a new perspective to explaining European history. His picture of the Middle Ages represents well that there is a way to integrate all typical Western motifs of post-war self-definition into a single theory. Mainly, the âliberty motifâ, as a sign of âEuropeanismâ â in the interpretation of BibĂłâs concept, Anglo-saxon Marxists and Weberâs social theory â, developed from medieval concepts of state and society and from an analysis of economic and social structures. SzƱcsâs historical aspect was a typical intellectual product of the 1980s: this was the time when a few Central European historians started to outline non-Marxist aspects of social theory and categories of modernisation theories, but concealing them with Marxist terminology
Unravelling an extended quark sector through multiple Higgs production?
In many new physics scenarios, the particle content of the Standard Model is extended and the Higgs couplings are modified, sometimes without affecting single Higgs production. We analyze two models with additional quarks. In these models, we compute double Higgs production from gluon fusion exactly at leading order, and present analytical results in the heavy-quark mass approximation. The experimental bounds from precision electroweak measurements and from the measured rate of single Higgs production combine to give significant restrictions for the allowed deviation of the double Higgs production rate from the Standard Model prediction as well as on the branching ratio for the Higgs decay into photons. The two models analyzed eventually present a similar Higgs phenomenology as the Standard Model. We connect this result to the magnitude of the dimension six operators contributing to the gluon-fusion Higgs production
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