15,234 research outputs found
Advanced high temperature heat flux sensors
To fully characterize advanced high temperature heat flux sensors, calibration and testing is required at full engine temperature. This required the development of unique high temperature heat flux test facilities. These facilities were developed, are in place, and are being used for advanced heat flux sensor development
On the precision of chiral-dispersive calculations of scattering
We calculate the combination (the Olsson sum rule)
and the scattering lengths and effective ranges , and ,
dispersively (with the Froissart--Gribov representation) using, at
low energy, the phase shifts for scattering obtained by Colangelo,
Gasser and Leutwyler (CGL) from the Roy equations and chiral perturbation
theory, plus experiment and Regge behaviour at high energy, or directly, using
the CGL parameters for s and s. We find mismatch, both among the CGL
phases themselves and with the results obtained from the pion form factor. This
reaches the level of several (2 to 5) standard deviations, and is essentially
independent of the details of the intermediate energy region ( GeV) and, in some cases, of the high energy behaviour assumed. We discuss
possible reasons for this mismatch, in particular in connection with an
alternate set of phase shifts.Comment: Version to appear in Phys. Rev. D. Graphs and sum rule added. Plain
TeX fil
An integrable multicomponent quad equation and its Lagrangian formulation
We present a hierarchy of discrete systems whose first members are the
lattice modified Korteweg-de Vries equation, and the lattice modified
Boussinesq equation. The N-th member in the hierarchy is an N-component system
defined on an elementary plaquette in the 2-dimensional lattice. The system is
multidimensionally consistent and a Lagrangian which respects this feature,
i.e., which has the desirable closure property, is obtained.Comment: 10 page
Soliton Solutions for ABS Lattice Equations II: Casoratians and Bilinearization
In Part I [arXiv:0902.4873 [nlin.SI]] soliton solutions to the ABS list of
multi-dimensionally consistent difference equations (except Q4) were derived
using connection between the Q3 equation and the NQC equations, and then by
reductions. In that work central role was played by a Cauchy matrix. In this
work we use a different approach, we derive the -soliton solutions following
Hirota's direct and constructive method. This leads to Casoratians and bilinear
difference equations. We give here details for the H-series of equations and
for Q1; the results for Q3 have been given earlier.Comment: 36 page
About the maximal rank of 3-tensors over the real and the complex number field
High dimensional array data, tensor data, is becoming important in recent
days. Then maximal rank of tensors is important in theory and applications. In
this paper we consider the maximal rank of 3 tensors. It can be attacked from
various viewpoints, however, we trace the method of Atkinson-Stephens(1979) and
Atkinson-Lloyd(1980). They treated the problem in the complex field, and we
will present various bounds over the real field by proving several lemmas and
propositions, which is real counterparts of their results.Comment: 13 pages, no figure v2: correction and improvemen
Convergence of expansions in Schr\"odinger and Dirac eigenfunctions, with an application to the R-matrix theory
Expansion of a wave function in a basis of eigenfunctions of a differential
eigenvalue problem lies at the heart of the R-matrix methods for both the
Schr\"odinger and Dirac particles. A central issue that should be carefully
analyzed when functional series are applied is their convergence. In the
present paper, we study the properties of the eigenfunction expansions
appearing in nonrelativistic and relativistic -matrix theories. In
particular, we confirm the findings of Rosenthal [J. Phys. G: Nucl. Phys. 13,
491 (1987)] and Szmytkowski and Hinze [J. Phys. B: At. Mol. Opt. Phys. 29, 761
(1996); J. Phys. A: Math. Gen. 29, 6125 (1996)] that in the most popular
formulation of the R-matrix theory for Dirac particles, the functional series
fails to converge to a claimed limit.Comment: Revised version, accepted for publication in Journal of Mathematical
Physics, 21 pages, 1 figur
Discovery of Interstellar Hydrogen Fluoride
We report the first detection of interstellar hydrogen fluoride. Using the
Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO), we
have detected the 121.6973 micron J = 2 - 1 line of HF in absorption toward the
far-infrared continuum source Sagittarius B2. The detection is statistically
significant at the 13 sigma level. On the basis of our model for the excitation
of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a
hydrogen fluoride abundance of 3E-10 relative to H2. If the elemental abundance
of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts
for ~ 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to
be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed
rapidly in exothermic reactions of atomic fluorine with either water or
molecular hydrogen; thus the measured HF abundance suggests a substantial
depletion of fluorine onto dust grains. Similar conclusions regarding depletion
have previously been reached for the case of chlorine in dense interstellar
clouds. We also find evidence at a lower level of statistical significance (~ 5
sigma) for an emission feature at the expected position of the 4(3,2)-4(2,3)
121.7219 micron line of water. The emission line equivalent width of 0.5 nm for
the water feature is consistent with the water abundance of 5E-6 relative to H2
that has been inferred previously from observations of the hot core of Sgr B2.Comment: 11 pages (AASTeX using aaspp4.sty) plus 2 figures; to appear in ApJ
Letter
Improved fidelity of triggered entangled photons from single quantum dots
We demonstrate the on-demand emission of polarisation-entangled photon pairs
from the biexciton cascade of a single InAs quantum dot embedded in a GaAs/AlAs
planar microcavity. Improvements in the sample design blue shifts the wetting
layer to reduce the contribution of background light in the measurements.
Results presented show that >70% of the detected photon pairs are entangled.
The high fidelity of the (|HxxHx>+|VxxVx>)/2^0.5 state that we determine is
sufficient to satisfy numerous tests for entanglement. The improved quality of
entanglement represents a significant step towards the realisation of a
practical quantum dot source compatible with applications in quantum
information.Comment: 9 pages. Paper is available free of charge at
http://www.iop.org/EJ/abstract/1367-2630/8/2/029/, see also 'A semiconductor
source of triggered entangled photon pairs', R. M. Stevenson et al., Nature
439, 179 (2006
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