2,055 research outputs found
NECAP 4.1: NASA's Energy Cost Analysis Program thermal response factor routine
A thermal response factor is described and calculation sequences and flowcharts for RESFAC2 are provided. RESFAC is used by NASA's (NECAP) to calculate hourly heat transfer coefficients (thermal response factors) for each unique delayed surface. NECAP uses these response factors to compute each spaces' hourly heat gain/loss
Chiral Magnetism of the Nucleon
We study the quark mass expansion of the magnetic moments of the nucleon in a
chiral effective field theory including nucleons, pions and delta resonances as
explicit degrees of freedom. We point out that the usual powercounting applied
so far to this problem misses important quark mass structures generated via an
intermediate isovector M1 nucleon-delta transition. We propose a modified
powercounting and compare the resulting chiral extrapolation function to
available (quenched) lattice data. The extrapolation is found to work
surprisingly well, given that the lattice data result from rather large quark
masses. Our calculation raises the hope that extrapolations of lattice data
utilizing chiral effective field theory might be applicable over a wider range
in quark masses than previously thought, and we discuss some open questions in
this context. Furthermore, we observe that within the current lattice data
uncertainties the extrapolations presented here are consistent with the Pade
fit ansatz introduced by the Adelaide group a few years ago.Comment: 30 pages, Latex, 7 figure
Thermal Dileptons from Quark and Hadron Phases of an Expanding Fireball
A fireball model with time evolution based on transport calculations is used
to examine the dilepton emission rate of an ultra-relativistic heavy-ion
collision. We assume a transition from hadronic matter to a quark-gluon plasma
at a critical temperature T_C between 130-170 MeV. We include thermal
corrections to the hadronic spectra below T_C and use perturbation theory above
T_C. The sensitivity of the spectra with respect to the freeze-out temperature,
the initial fireball temperature and the critical temperature is investigated.Comment: 14 pages, 5 figures; paragraph and one figure added; version to
appear in Eur. Phys. J.
Comment on "Surprises in threshold antikaon-nucleon physics"
It has recently been claimed by Oller et al. [PRL 95 (2005) 172502] that the
DEAR kaonic hydrogen data can be reconciled with K^- p scattering data in a
chiral unitary approach. In this comment we demonstrate that the proposed
solution violates fundamental principles of scattering theory.Comment: 1 page, 1 figur
Note on finite temperature sum rules for vector and axial-vector spectral functions
An updated analysis of vector and axial-vector spectral functions is
presented. The resonant contributions to the spectral integrals are shown to be
expressible as multiples of 4 pi^2 f_pi^2, encoding the scale of spontaneous
chiral symmetry breaking in QCD. Up to order T^2 this behavior carries over to
the case of finite temperature.Comment: 10 pages, 2 figure
Hire Education: Mastery, Modularization and the Workforce Revolution
This new research identifies online competency-based learning as the solution to shifting demands for specialized workforce skills and the front runner for disrupting higher education
Chiral extrapolations of nucleon properties from lattice QCD
We report on recent work about the study of quark mass dependence of nucleon
magnetic moments and axial-vector coupling constant. We examine the feasibility
of chiral effective field theory methods for the extrapolation of lattice QCD
data obtained at relative large pion masses down to the physical values.Comment: 5pages, LaTeX, 3 figures, uses World Scientific style file; presented
at PANIC 02, Osak
Model for dilepton rates from a fireball
We calculate the dilepton emission rate from a fireball created in an
ultra-relativistic heavy-ion collision. For the partonic phase, we complement
the perturbative results by a phenomenological approach based on lattice QCD
results, whereas in the hadronic phase temperature and finite baryon density
effects on the spectral function are considered. The resulting rates are
compared to data from CERES/NA45.Comment: 4 pages, 3 figures. Talk given at 15th International Conference on
Ultrarelativistic Nucleus-Nucleus Collisions (QM2001), Stony Brook, New York,
15-20 Jan 200
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