9,194 research outputs found
Nucleon-Nucleon Scattering From Fully-Dynamical Lattice QCD
We present results of the first fully-dynamical lattice QCD determination of
nucleon-nucleon scattering lengths in the 1S0 channel and 3S1-3D1 coupled
channels. The calculations are performed with domain-wall valence quarks on the
MILC staggered configurations with lattice spacing of b=0.125 fm in the
isospin-symmetric limit, and in the absence of electromagnetic interactions.Comment: 4 pages, 4 figure
I=2 pi-pi Scattering from Fully-Dynamical Mixed-Action Lattice QCD
We compute the I=2 pi-pi scattering length at pion masses of m_pi ~ 294, 348
and 484 MeV in fully-dynamical lattice QCD using Luscher's finite-volume
method. The calculation is performed with domain-wall valence-quark propagators
on asqtad-improved MILC configurations with staggered sea quarks at a single
lattice spacing, b ~ 0.125 fm. Chiral perturbation theory is used to perform
the extrapolation of the scattering length from lattice quark masses down to
the physical value, and we find m_pi a_2 = -0.0426 +- 0.0006 +- 0.0003 +-
0.0018, in good agreement with experiment. The I=2 pi-pi scattering phase shift
is calculated to be delta = -43 +- 10 +- 5 degrees at |p| ~ 544 MeV for m_pi ~
484 MeV.Comment: 16 pages, 4 figure
In-flight absolute radiometric calibration of the thematic mapper
The TM multispectral scanner system was calibrated in an absolute manner before launch. To determine the temporal changes of the absolute radiometric calibration of the entire system, spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM collections over White Sands, New Mexico. By entering the measured values in an atmospheric radiative transfer program, the radiance levels of the in four of the spectral bands of the TM were determined. Tables show values for the reflectance of snow at White Sands measured by a modular 8 channel radiometer, and values for exoatmospheric irradiance within the TM passbands, calculated for the Earth-Sun distance using a solar radiometer
In-flight absolute radiometric calibration of the thematic mapper
In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, New Mexico area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1:0.45 to 0.52 micrometers, band 2:0.53 to 0.61 micrometers band 3:0.62 to 0.70 micrometers and 4:0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors
The properties of highly luminous IRAS galaxies
From a complete sample of 154 galaxies identified with IRAS sources in a 304 sq deg area centered on the South Galactic Pole, a subsample of 58 galaxies with L sub IR/L sub B > 3 was chosen. Low resolution spectra were obtained for 30% of the subsample and redshifts and relative emission line intensities were derived. As a class these galaxies are very luminous with = 2.9 x 10 to the 11th power L sub 0 and (L sub IR) max = 1.3 x 10 to the 12th power L sub 0. CCD images and JHK photometry were obtained for many of the subsample. The galaxies are for the most part newly identified and are optically faint, with a majority showing evidence of a recent interaction. Radio continuum observations of all galaxies of the subsample were recently obtained at 20 cm VLA with about 75% being detected in a typical integration time of about 10 minutes
Spatial and temporal filtering of a 10-W Nd:YAG laser with a Fabry-Perot ring-cavity premode cleaner
We report on the use of a fixed-spacer Fabry–Perot ring cavity to filter spatially and temporally a 10-W laser-diode-pumped Nd:YAG master-oscillator power amplifier. The spatial filtering leads to a 7.6-W TEMinfinity beam with 0.1% higher-order transverse mode content. The temporal filtering reduces the relative power fluctuations at 10 MHz to 2.8 x 10^-/sqrtHz, which is 1 dB above the shot-noise limit for 50 mA of detected photocurrent
Collapsing Bose-Einstein condensates beyond the Gross-Pitaevskii approximation
We analyse quantum field models of the bosenova experiment, in which
Rb Bose-Einstein condensates were made to collapse by switching their
atomic interactions from repulsive to attractive. Specifically, we couple the
lowest order quantum field correlation functions to the Gross-Pitaevskii
function, and solve the resulting dynamical system numerically. Comparing the
computed collapse times with the experimental measurements, we find that the
calculated times are much larger than the measured values. The addition of
quantum field corrections does not noticeably improve the agreement compared to
a pure Gross-Pitaevskii theory.Comment: 8 pages, 4 figure
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