2,423 research outputs found
R-Parity Violating Supersymmetry Explanation for Large t tbar Forward-Backward Asymmetry
We propose a supersymmetric explanation for the anomalously high forward
backward asymmetry in top pair production measured by CDF and D0. We suppose
that it is due to the t-channel exchange of a right-handed sbottom which
couples to d_R and t_R, as is present in the R-parity violating minimal
supersymmetric standard model. We show that all Tevatron and LHC experiments' t
tbar constraints may be respected for a sbottom mass between 300 and 1200 GeV,
and a large Yukawa coupling >2.2, yielding A_{FB} up to 0.18. The non Standard
Model contribution to the LHC charge asymmetry parameter is Delta
A_C^y=0.017-0.045, small enough to be consistent with current measurements but
non-zero and positive, allowing for LHC confirmation in the future within 20
fb^-1. A small additional contribution to the LHC t tbar production
cross-section is also predicted, allowing a further test. We estimate that 10
fb^-1 of LHC luminosity would be sufficient to rule out the proposal to 95%
confidence level, if the measurements of the t tbar cross-section turn out to
be centred on the Standard Model prediction.Comment: 5 pages, 2 figures, v2 has added comments and references and
increased statistics, leading to more accurate numerical predictions. v3 has
typos in Fig 1 fixed: arrow directions and t and tbar labels. v4 has added
discussion and corrections to Eq 4. v5 has luminosity predictions, additional
checks and small numerical change
Investigating the Supersymmetric Explanation of Anomalous CDF lepton(s) photon(s) Missing-E_T Events
The recent excess over the Standard Model prediction in the \mu \gamma
missing-E_T channel reported by CDF can be well-explained by resonant smuon
production with a single dominant R-parity violating coupling \lambda'_{211},
in the context of models where the gravitino is the lightest supersymmetric
particle. The slepton decays to the lightest neutralino and a muon followed by
neutralino decaying to a gravitino and photon. The kinematical distributions
are fitted well by our hypothesis and we use them to constrain the available
parameter space. The model also provides an explanation for the ee\gamma\gamma
missing-E_T event observed in Run I of the Tevatron by the CDF experiment. Our
model predicts an excess of between 5 and 35 events in a \gamma missing-E_T
channel at Run I. We provide predictions for signatures expected by the model
at Run II.Comment: 23 pages, Latex file + 10 figures and 4 Tables (included) Includes
JHEP3.cls and axodraw.st
Configuration management and automatic control of an augmentor wing aircraft with vectored thrust
An advanced structure for automatic flight control logic for powered-lift aircraft operating in terminal areas is under investigation at Ames Research Center. This structure is based on acceleration control; acceleration commands are constructed as the sum of acceleration on the reference trajectory and a corrective feedback acceleration to regulate path tracking errors. The central element of the structure, termed a Trimmap, uses a model of the aircraft aerodynamic and engine forces to calculate the control settings required to generate the acceleration commands. This report describes the design criteria for the Trimmap and derives a Trimmap for Ames experimental augmentor wing jet STOL research aircraft
Oxygen production on Mars and the Moon
Significant progress was made in the area of in-situ oxygen production in the last year. In order to reduce sealing problems due to thermal expansion mismatch in the disk configuration, several all-Zirconia cells were constructed and are being tested. Two of these cells were run successfully for extended periods of time. One was run for over 200 hours and the other for over 800 hours. These extended runs, along with gas sample analysis, showed that the oxygen being produced is definitely from CO2 and not from air leaks or from the disk material. A new tube system is being constructed that is more rugged, portable, durable, and energy efficient. The important operating parameters of this system will be better controlled compared to previous systems. An electrochemical compressor will also be constructed with a similar configuration. The electrochemical compressor will use less energy since the feed stock is already heated in the separation unit. In addition, it does not have moving parts
Correlations due to localization in quantum eigenfunctions of disordered microwave cavities
Non-universal correlations due to localization are observed in statistical
properties of experimental eigenfunctions of quantum chaotic and disordered
microwave cavities. Varying energy {E} and mean free path {l} enable us to
experimentally tune from localized to delocalized states. Large level-to-level
Inverse Participation Ratio (IPR I_{2}) fluctuations are observed for the
disordered billiards, whose distribution is strongly asymmetric about .
The density auto-correlations of eigenfunctions are shown to decay
exponentially and the decay lengths are experimentally determined. All the
results are quantitatively consistent with calculations based upon nonlinear
sigma-models.Comment: 4 pages, LaTex, 5 .jpg figures. This paper with 5 embedded postscript
figures available (PS,PDF) at http://sagar.physics.neu.edu/preprints
PROTON PUMP INHIBITORS AND THE RISK OF CHRONIC KIDNEY DISEASES: A CRITICAL REVIEW
Proton pump inhibitors (PPIs) are most widely used medications for acid related gastrointestinal disorders. Accessible evidence based studies suggest that the increased use of PPI is linked to a greater risk of developing kidney diseases. This review aims to determine the association of kidney disease with the use of proton pump inhibitor with various study designs. PubMed, Scopus and Google Scholar databases as well as a reference list of relevant articles were systematically searched for studies by using the following search terms; ‘proton pump inhibitors’, ‘acute kidney injury’, ‘chronic kidney disease’ and ‘end stage renal disease’. Both observational and randomized controlled trials (RCTs) exploring the association of PPI use with kidney disease were eligible for inclusion. A total of 8 articles, including 9 studies (n = 794,349 participants) were identified and included in the review. Majority of the studies showed a higher risk of kidney outcomes in patients taking PPIs, with effect higher of acute kidney injury (4-to 6-fold) compared with chronic kidney disease and end stage renal disease (1.5-to 2.5-fold). However, the studies suggest that the strength of evidence is weak and could not prove causation. The risk increased considerably with the use of high dose of PPIs and prolonged duration of exposure necessitates the monitoring of renal function. Exercising vigilance in PPI use and cessation of proton pump inhibitor when there is no clear indication may be a reasonable approach to reduce the population burden of kidney diseases
Dendrite growth direction measurements : understanding the solute advancement in continuous casting of steel
Maintaining competitiveness in steel manufacturing requires improving process efficiency and production volume whilst enhancing product quality and performance. This is particularly challenging for producing value-added advanced steel grades such as advanced high strength steels and electrical steels. These grades due to higher weight percentage of alloying elements cause difficulties in various stages of upstream and downstream processing, and this includes continuous casting, wherein high solute levels are critical towards macro-segregation. Interface growth direction in systems with more than one component is dictated by the solute profile ahead of the moving solidification front. Understanding the profile of growth direction with casting process parameters during the progress of casting will provide an important perspective towards reducing the macro-segregation in the cast product. In the present study, two steel slab samples from conventional slab caster under the influence of electromagnetic brake (EMBR) at Tata Steel in IJmuiden (The Netherlands) have been investigated for dendrite deflection measurements. The samples showed a transition zone where a change in the deflection behavior occurs. Also, the magnitude of the deflection angle decreases away from the slab surface. Correlating these experimental data with modeled fluid flow profile will help in improving the understanding of the dynamic nature of the solute advancement so that the casting parameters can be optimized to improve product quality
1,5-Dimethyl-3-oxo-2-phenyl-2,3-diÂhyÂdro-1H-pyrazol-4-aminium 2-hydroxyÂbenzoate
In the title salt, C11H14N3O+·C7H5O3
−, the phenyl ring of the cation is oriented at an angle of 67.0 (1)° with respect to the five-membered pyrazolone ring. The carboxylÂate plane of the anion is twisted out from the plane of the aromatic ring at an angle of 13.7 (3)°. In the crystal, the cations form hydrogen-bonded dimers with an R
2
2(10) ring motif. The salicylate anion has an intraÂmolecular O—H⋯O hydrogen bond
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