8 research outputs found
Pion photoproduction off the proton in a gauge-invariant chiral unitary framework
We investigate pion photoproduction off the proton in a manifestly
gauge-invariant chiral unitary extension of chiral perturbation theory. In a
first step, we consider meson-baryon scattering taking into account all
next-to-leading order contact interactions. The resulting low-energy constants
are determined by a fit to s-wave pion-nucleon scattering and the low-energy
data for the reaction pi- p --> eta n. To assess the theoretical uncertainty,
we perform two different fit strategies. Having determined the low-energy
constants, we then analyse the data on the s-wave multipole amplitudes E0+ of
pion and eta photoproduction. These are parameter-free predictions, as the two
new low-energy constants are determined by the neutron and proton magnetic
moments.Comment: 23 pages, 17 figure
Pion photoproduction on nucleons in a covariant hadron-exchange model
We present a relativistic dynamical model of pion photoproduction on the
nucleon in the resonance region. It offers several advances over the existing
approaches. The model is obtained by extending our -scattering
description to the electromagnetic channels. The resulting photopion amplitude
is thus unitary in the , \ga N channel space, Watson's theorem is
exactly satisfied. At this stage we have included the pion, nucleon,
\De(1232)-resonance degrees of freedom. The and meson
exchanges are also included, but play a minor role in the considered energy
domain (up to GeV). In this energy range the model provides a
good description of all the important multipoles. We have allowed for only two
free parameters -- the photocouplings of the -resonance. These
couplings are adjusted to reproduce the strength of corresponding
resonant-multipoles and at the resonance position.Comment: 17 pages, 4 figs, version to appear in Phys. Rev. C 70 (2004
Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus -- the "D-shuttle" project --
Twelve high schools in Japan (of which six are in Fukushima Prefecture), four
in France, eight in Poland and two in Belarus cooperated in the measurement and
comparison of individual external doses in 2014. In total 216 high-school
students and teachers participated in the study. Each participant wore an
electronic personal dosimeter "D-shuttle" for two weeks, and kept a journal of
his/her whereabouts and activities. The distributions of annual external doses
estimated for each region overlap with each other, demonstrating that the
personal external individual doses in locations where residence is currently
allowed in Fukushima Prefecture and in Belarus are well within the range of
estimated annual doses due to the background radiation level of other
regions/countries