434 research outputs found
Photo- and Electroproduction of Eta Mesons
Eta photo- and electroproduction off the nucleon is investigated in an
effective lagrangian approach that contains Born terms and both vector meson
and nucleon resonance contributions. In particular, we review and develop the
formalism for coincidence experiments with polarization degrees of freedom. The
different response functions appearing in single and double polarization
experiments have been studied. We will present calculations for structure
functions and kinematical conditions that are most sensitive to details of the
lagrangian, in particular with regard to contributions of nucleon resonances
beyond the dominant (1535) resonance.Comment: 24 pages RevTeX/LaTeX2.09, NFSS1, 13 figures (in separate file
(tar,gzip and uue)), accepted for publication in Z. Phys.
What is limiting near-infrared astrometry in the Galactic Center?
We systematically investigate the error sources for high-precision astrometry
from adaptive optics based near-infrared imaging data. We focus on the
application in the crowded stellar field in the Galactic Center. We show that
at the level of <=100 micro-arcseconds a number of effects are limiting the
accuracy. Most important are the imperfectly subtracted seeing halos of
neighboring stars, residual image distortions and unrecognized confusion of the
target source with fainter sources in the background. Further contributors to
the error budget are the uncertainty in estimating the point spread function,
the signal-to-noise ratio induced statistical uncertainty, coordinate
transformation errors, the chromaticity of refraction in Earth's atmosphere,
the post adaptive optics differential tilt jitter and anisoplanatism. For stars
as bright as mK=14, residual image distortions limit the astrometry, for
fainter stars the limitation is set by the seeing halos of the surrounding
stars. In order to improve the astrometry substantially at the current
generation of telescopes, an adaptive optics system with high performance and
weak seeing halos over a relatively small field (r<=3") is suited best.
Furthermore, techniques to estimate or reconstruct the seeing halo could be
promising.Comment: accepted by MNRAS, 13 pages, 14 figure
Mitochondrial localization of a NADR-dependent isocitrate dehydrogenase isoenzyme by using the green fluorescent protein as a marker
To Separate or Not to Separate Investment from Commercial Banking? An Empirical Analysis of Attention Distortion Under Multiple Tasks
The Macroeconomic Effects of the Euro Area's Fiscal Consolidation 2011-2013: A Simulation-Based Approach
The Impact of Social Support Networks on Maternal Employment: A Comparison of West German, East German and Migrant Mothers of Pre-School Children
Self-productivity and complementarities in human development : evidence from MARS
This paper investigates the role of self-productivity and home resources in capability formation from infancy to adolescence. In addition, we study the complementarities between basic cognitive, motor and noncognitive abilities and social as well as academic achievement. Our data are taken from the Mannheim Study of Children at Risk (MARS), an epidemiological cohort study following the long-term outcome of early risk factors. Results indicate that initial risk conditions cumulate and that differences in basic abilities increase during development. Self-productivity rises in the developmental process and complementarities are evident. Noncognitive abilities promote cognitive abilities and social achievement. There is remarkable stability in the distribution of the economic and socio-emotional home resources during the early life cycle. This is presumably a major reason for the evolution of inequality in human development
K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76 TeV
The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76 TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4 GeV/c (0.6 GeV/c for Λ) to 12 GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3 GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9 TeV and at s√=7 TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2 GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio
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