2,891 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.
Reworking the Tucson-Melbourne Three-Nucleon Potential
We introduce new values of the strength constants (i.e., , , , and
coefficients) of the Tucson-Melbourne (TM) 2 exchange three nucleon
potential. The new values come from contemporary dispersion relation analyses
of meson factory N scattering data. We make variational Monte Carlo
calculations of the triton with the original and updated three-body forces to
study the effects of this update. We remove a short-range -- -range part
of the potential due to the coefficient and discuss the effect on the
triton binding energy.Comment: 12 pages, to appear in Few-Body System
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
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
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