45,139 research outputs found
Stability of P11 Resonance Extracted from pi-N Data
We address a question about how much resonance poles and residues extracted
from data depend on a model used for the extraction, and on the precision of
data. We focus on the P11 pi-N scattering and use the dynamical coupled-channel
(DCC) model developed in Excited Baryon Analysis Center (EBAC) at JLab. We
examine the model-dependence of the poles by varying parameters largely within
the EBAC-DCC model. We find that two poles associated with the Roper resonance
are fairly stable against the variation. We also study the stability of the
Roper poles against different analytic structure of the P11 amplitude below
pi-N threshold by using a bare nucleon model. We again find a good stability of
the Roper poles.Comment: 4 pages, 4 figures, Contribution to the proceedings of 12th
International Conference on Meson-Nucleon Physics and the Structure of the
Nucleon (MENU2010), Williamsburg, USA, May 31-June 4 201
Evaluation of truncation error and adaptive grid generation for the transonic full potential flow calculations
The effects of truncation error on the numerical solution of transonic flows using the full potential equation are studied. The effects of adapting grid point distributions to various solution aspects including shock waves is also discussed. A conclusion is that a rapid change of grid spacing is damaging to the accuracy of the flow solution. Therefore, in a solution adaptive grid application an optimal grid is obtained as a tradeoff between the amount of grid refinement and the rate of grid stretching
Gauge-invariant variables in general-relativistic perturbations: globalization and zero-mode problem
An outline of a proof of the local decomposition of linear metric
perturbations into gauge-invariant and gauge-variant parts on an arbitrary
background spacetime is briefly explained. We explicitly construct the
gauge-invariant and gauge-variant parts of the linear metric perturbations
based on some assumptions. We also point out the zero-mode problem is an
essential problem to globalize of this decomposition of linear metric
perturbations. The resolution of this zero-mode problem implies the possibility
of the development of the higher-order gauge-invariant perturbation theory on
an arbitrary background spacetime in a global sense.Comment: (v1) 16 pages, no figure; (v2) 9 pages, no figure. Compactified for
"2012 Awards for Essays on Gravitation" promoted by Gravity Research
Foundation. References are deleted. no ingredients is changed. This version
received Honorable Mention for 201
Monte Carlo Study of Two-Color QCD with Finite Chemical Potential - Status report of Wilson fermion simulation
Using Wilson fermions, we study SU(2) lattice QCD with the chemical potential
at . The ratio of fermion determinants is evaluated at each
Metropolis link update step. We calculate the baryon number density, the
Polyakov loops and the pseudoscalar and vector masses on and lattices. Preliminary data show the pseudoscalar meson becomes massive
around , which indicates the chiral symmetry restoration. The
calculation is broken down when approaching to the transition region. We
analyze the behavior of the fermion determinant and eigen value distributions
of the determinant, which shows a peculiar ``Shell-and-Bean'' pattern near the
transition.Comment: 4 pages, 5 figures, Lattice 2000 (Finite Density
COST PASS-THROUGH IN THE U.S. COFFEE INDUSTRY
A rich data set of coffee prices and costs was used to determine to what extent changes in commodity costs affect manufacturer and retail prices. On average, a 10-cent increase in the cost of a pound of green coffee beans in a given quarter results in a 2-cent increase in manufacturer and retail prices in that quarter. If a cost change persists for several quarters, it will be incorporated into manufacturer prices approximately cent-forcent with the commodity-cost change. Given the substantial fixed costs and markups involved in coffee manufacturing, this translates into about a 3-percent change in retail prices for a 10-percent change in commodity prices. We do not find robust evidence that coffee prices respond more to increases than to decreases in costs.cost pass-through, retail prices, manufacturer prices, commodity costs, coffee, Demand and Price Analysis,
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