4,294 research outputs found
Darwin-Foldy term and proton charge radius
In this contribution we study the Dirac equation for a finite size proton in
an external electric field with explicit introduction of Dirac-Pauli form
factors. Our aim is twofold. On the one hand, we wish to study whether our
conclusions regarding the exact cancellation between Dirac form factor and
Foldy term contributions occurring for the neutron still hold for the proton.
On the other hand, we wish to clearly illustrate some of the specific features
of the description of a composite particle like the proton with the Dirac
equation.Comment: contribution to XVIIth European Conference of Few-Body Problems in
Physics, Evora, Portugal Sept 2000, to be published in Nucl. Phys.
Meson PVV Interactions are determined by Quark Loops
We show that all abnormal parity three-body meson interactions can be
adequately described by quark loops, evaluated at zero external momentum, with
couplings determined by symmetry. We focus primarily on radiative
meson decays which involve one pseudoscalar. The agreement with experiment for
non-rare decays is surprisingly good and requires very few parameters, namely
the coupling constants and and some mixing angles.
This agreement extends to some three-body decays that are dominated by pion
pairs in a P-wave state.Comment: 21 pages, Revtex, one figur
Vector Meson Dominance and Rho-Omega Mixing
The scale of a phenomenologically successful charge-symmetry-violating
nucleon-nucleon interaction, that attributed to meson exchange with a rho-omega transition, is set by the Coleman-Glashow SU(2) breaking tadpole
mechanism. A single tadpole scale has been obtained from symmetry arguments,
electromagnetic meson and baryon measured mass splittings, and the observed
isospin violating () decay . The hadronic
realization of this tadpole mechanism lies in the scalar meson.
We show that measured hadronic and two-photon widths of the meson, with
the aid of the Vector Meson Dominance model, recover the universal
Coleman-Glashow tadpole scale.Comment: 18 pages, 2 figures, to appear in Physical Review
Momentum and Coordinate Space Three-nucleon Potentials
In this paper we give explicit formulae in momentum and coordinate space for
the three-nucleon potentials due to and meson exchange, derived
from off-mass-shell meson-nucleon scattering amplitudes which are constrained
by the symmetries of QCD and by the experimental data. Those potentials have
already been applied to nuclear matter calculations. Here we display additional
terms which appear to be the most important for nuclear structure. The
potentials are decomposed in a way that separates the contributions of
different physical mechanisms involved in the meson-nucleon amplitudes. The
same type of decomposition is presented for the TM force: the
, the chiral symmetry breaking and the nucleon pair terms are isolated.Comment: LATEX, 33 pages, 3 figures (available as postscript files upon
request
Off-Mass-Shell N Scattering and
We adapt the off-shell N amplitude of the Tucson-Melbourne three-body
force to the half-off-shell amplitude of the pion rescattering contribution to
near threshold. This {\em pion} rescattering contribution,
together with the impulse term, provides a good description of the data when
the half-off-shell amplitude is linked to the phenomenological invariant
amplitudes obtained from meson factory N scattering data.Comment: 3 pages, contributed to STORRI99, Bloomington, Indiana, September
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RESULTS OF THE RURAL CASS COUNTY BUSINESS AND SERVICES PREFERENCE SURVEY
Changing demographics in rural and urban North Dakota have provided both opportunities and challenges for rural communities. Cass County boasts the state's largest and fastest growing urban center, but the impact of the county's growth extends beyond the Fargo-West Fargo city limits. Towns like Casselton, Horace, and Kindred have experienced substantial changes not only in the number of residents, but also in the composition of households and their business and service needs and preferences. To address these questions, the Rural Cass County Business and Services Preference Survey was designed to identify and quantify residents' perceptions on a variety of issues. This report details respondents' perceptions on quality of life issues, business and service patronization, as well as describes some basic demographic characteristics of rural Cass County residents.rural development, rural Cass County, population growth, Community/Rural/Urban Development,
Channel and noise variance estimation and tracking algorithms for unique-word based single-carrier systems
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