24,657 research outputs found
Nonet Symmetry and Two-Body Decays of Charmed Mesons
The decay of charmed mesons into pseudoscalar (P) and vector (V) mesons is
studied in the context of nonet symmetry. We have found that it is badly broken
in the PP channels and in the P sector of the PV channels as expected from the
non-ideal mixing of the \eta and the \eta'. In the VV channels, it is also
found that nonet symmetry does not describe the data well. We have found that
this discrepancy cannot be attributed entirely to SU(3) breaking at the usual
level of 20--30%. At least one, or both, of nonet and SU(3) symmetry must be
very badly broken. The possibility of resolving the problem in the future is
also discussed.Comment: 9 pages, UTAPHY-HEP-
Energy and Momentum of a Class of Rotating Gravitational Waves
We calculate energy and momentum for a class of cylindrical rotating
gravitational waves using Einstein and Papapetrou's prescriptions. It is shown
that the results obtained are reduced to the special case of the cylindrical
gravitational waves already available in the literature.Comment: 11 pages, no figure, Late
Gastric perforation and pancreatitis manifesting after an inadvertent nissen fundoplication in a patient with superior mesenteric artery syndrome.
Superior mesenteric artery (SMA) syndrome is an uncommon but well-recognized clinical entity. It can lead to proximal small bowel obstruction and severe morbidity and mortality in lieu of late diagnosis and concomitant existing comorbidities. We report a 54-year-old female, with SMA syndrome which manifested itself after Nissen fundoplication along with two major complications. The diagnosis of SMA was established by clinical symptoms and radiological findings
Financial Aid Packages and College Enrollment Decisions: An Econometric Case Study
We study the effects of a change in financial aid policy introduced by a Northeastern university in 1998. Prior to that time, the university's financial aid packages for low-income students consisted of grants, loans, and campus jobs. After the change, the entire loan portion of the package for low-income students was replaced with grants. We find the program increased the likelihood of matriculation by low-income students by about 3 percentage points, although the effect is not statistically significant. The effect among low-income minority students was between 8 and 10 percentage points and statistically significant at the 10 percent level.
The measurement errors in the Swift-UVOT and XMM-OM
The probability of photon measurement in some photon counting
instrumentation, such as the Optical Monitor on the XMM-Newton satellite, and
the UVOT on the Swift satellite, does not follow a Poisson distribution due to
the detector characteristics, but a Binomial distribution. For a single-pixel
approximation, an expression was derived for the incident countrate as a
function of the measured count rate by Fordham, Moorhead and Galbraith (2000).
We show that the measured countrate error is binomial, and extend their
formalism to derive the error in the incident count rate. The error on the
incident count rate at large count rates is larger than the Poisson-error of
the incident count rate.Comment: 4 pages, 2 postscript figures, submitted to MNRA
Energy-Momentum Distribution: Some Examples
In this paper, we elaborate the problem of energy-momentum in General
Relativity with the help of some well-known solutions. In this connection, we
use the prescriptions of Einstein, Landau-Lifshitz, Papapetrou and M\"{o}ller
to compute the energy-momentum densities for four exact solutions of the
Einstein field equations. We take the gravitational waves, special class of
Ferrari-Ibanez degenerate solution, Senovilla-Vera dust solution and
Wainwright-Marshman solution. It turns out that these prescriptions do provide
consistent results for special class of Ferrari-Ibanez degenerate solution and
Wainwright-Marshman solution but inconsistent results for gravitational waves
and Senovilla-Vera dust solution.Comment: 20 pages, accepted for publication in Int. J. Mod. Phys.
Sufficient conditions for the existence of Q-balls in gauge theories
We formulate a set of simple sufficient conditions for the existence of
Q-balls in gauge theories.Comment: 5 page
Charge-Focusing Readout of Time Projection Chambers
Time projection chambers (TPCs) have found a wide range of applications in
particle physics, nuclear physics, and homeland security. For TPCs with
high-resolution readout, the readout electronics often dominate the price of
the final detector. We have developed a novel method which could be used to
build large-scale detectors while limiting the necessary readout area. By
focusing the drift charge with static electric fields, we would allow a small
area of electronics to be sensitive to particle detection for a much larger
detector volume. The resulting cost reduction could be important in areas of
research which demand large-scale detectors, including dark matter searches and
detection of special nuclear material. We present simulations made using the
software package Garfield of a focusing structure to be used with a prototype
TPC with pixel readout. This design should enable significant focusing while
retaining directional sensitivity to incoming particles. We also present first
experimental results and compare them with simulation.Comment: 5 pages, 17 figures, Presented at IEEE Nuclear Science Symposium 201
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