1,936 research outputs found
First NACO observations of the Brown Dwarf LHS 2397aB
Observations of the standard late type M8 star LHS 2397aA were obtained at
the ESO-VLT 8m telescope ``Yepun'' using the NAOS/CONICA Adaptive Optics
facility. The observations were taken during the NACO commissioning, and the
infrared standard star LHS 2397aA was observed in the H, and Ks broad band
filters. In both bands the brown dwarf companion LHS2397aB was detected. Using
a program recently developed (Bouy et al., 2003) for the detection of stellar
binaries we calculated the principal astrometric parameters (angular binary
separation and position angle P.A.) and the photometry of LHS 2397aA and LHS
2397aB. Our study largely confirms previous results obtained with the
AO-Hokupa'a facility at Gemini-North (Freed et al., 2003); however a few
discrepancies are observed.Comment: 5 page
Technologies, markets and challenges for development of the Canadian Oil Sands industry
This paper provides an overview of the current status of development of the Canadian oil sands industry, and considers possible paths of further development. We outline the key technology alternatives, critical resource inputs and environmental challenges and strategic options both at the company and government level. We develop a model to calculate the supply cost of bitumen and synthetic crude oil using the key technologies. Using the model we evaluate the sensitivity of the supply costs to the critical model inputs
On the nature of the residual meson-meson interaction from simulations with a QED model
A potential between mesons is extracted from 4-point functions within lattice
gauge theory taking 2+1 dimensional QED as an example. This theory possesses
confinement and dynamical fermions. The resulting meson-meson potential has a
short-ranged hard repulsive core and the expected dipole-dipole forces lead to
attraction at intermediate distances. Sea quarks lead to a softer form of the
total potential.Comment: 4 pages, uuencoded tar-compressed postscript file, contribution to
Lattice'9
Three-Nucleon Force and the -Mechanism for Pion Production and Pion Absorption
The description of the three-nucleon system in terms of nucleon and
degrees of freedom is extended to allow for explicit pion production
(absorption) from single dynamic de-excitation (excitation) processes.
This mechanism yields an energy dependent effective three-body hamiltonean. The
Faddeev equations for the trinucleon bound state are solved with a force model
that has already been tested in the two-nucleon system above pion-production
threshold. The binding energy and other bound state properties are calculated.
The contribution to the effective three-nucleon force arising from the pionic
degrees of freedom is evaluated. The validity of previous coupled-channel
calculations with explicit but stable isobar components in the
wavefunction is studied.Comment: 23 pages in Revtex 3.0, 9 figures (not included, available as
postscript files upon request), CEBAF-TH-93-0
Skyrmions and the Nuclear Force
The derivation of the nucleon-nucleon force from the Skyrme model is
reexamined. Starting from previous results for the potential energy of
quasistatic solutions, we show that a calculation using the Born-Oppenheimer
approximation properly taking into account the mixing of nucleon resonances,
leads to substantial central attraction. We obtain a potential that is in
qualitative agreement with phenomenological potentials. We also study the
non-adiabatic corrections, such as the velocity dependent transition
potentials, and discuss their importance.Comment: 24 pages, UPR-0124M
Administrator Surveys as Alternative Policy Instruments
Little attention has been given to the professional development needs of educational administrators
Cross section and analyzing power of pol{p}p -> pn pi+ near threshold
The cross section and analyzing power of the pol{p}p -> pn pi+ reaction near
threshold are estimated in terms of data obtained from the pol{p}p -> d pi+ and
pp -> pp pi0 reactions. A simple final state interaction theory is developed
which depends weakly upon the form of the pion-production operator and includes
some Coulomb corrections. Within the uncertainties of the model and the input
data, the approach reproduces well the measured energy dependence of the total
cross section and the proton analyzing power at a fixed pion c.m. angle of
90deg, from threshold to T_p = 330 MeV. The variation of the differential cross
section with pion angle is also very encouraging.Comment: 20 pages, Latex including 4 eps figure
Baryon-Baryon Potentials on the Lattice
The interaction of spatially extended heavy baryons is investigated in the
framework of lattice QCD with dynamical quarks. It is shown that the expected
dipole forces have a very short range and that the baryon-antibaryon
interaction is more attractive than the baryon-baryon interaction. Sea quarks
play a minor important role.Comment: 8 pages, uuencoded postscript file; Physics Letters B, in pres
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