197 research outputs found
Magnetic Moments of the Baryon Decuplet in a Relativistic Quark Model
The magnetic moments of the baryon decuplet are calculated in a relativistic
constituent quark model using the light-front formalism. Of particular interest
are the magnetic moments of the and for which new
recent experimental measurements are available. Our calculation for the
magnetic moment ratio is in excellent agreement with
the experimental ratio, while our ratio is
slightly higher than the experimental ratio.Comment: 10 pages ReVTeX, SLAC-PUB-621
Ratios of Elastic Scattering of Pions from 3H and 3He
We have measured the elastic-scattering ratios of normalized yields for
charged pions from 3H and 3He in the backward hemisphere. At 180 MeV, we
completed the angular distribution begun with our earlier measurements, adding
six data points in the angular range of 119 deg to 169 deg in the pi-nucleus
center of mass. We also measured an excitation function with data points at
142, 180, 220, and 256 MeV incident pion energy at the largest achievable angle
for each energy between 160 deg and 170 deg in the pi-nucleus center of mass.
This excitation function corresponds to the energies of our forward-hemisphere
studies. The data, taken as a whole, show an apparent role reversal of the two
charge-symmetric ratios r1 and r2 in the backward hemisphere. Also, for data >
100 deg we observe a strong dependence on the four-momentum transfer squared
(-t) for all of the ratios regardless of pion energy or scattering angle, and
we find that the superratio R data match very well with calculations based on
the forward-hemisphere data that predicts the value of the difference between
the even-nucleon radii of 3H and 3He. Comparisons are also made with recent
calculations incorporating different wave functions and double scattering
models.Comment: RevTex 8pages, 12 figure file
Delta--Excitation and Exchange Corrections for NN--Bremsstrahlung
The role of the relativistic amplitudes for a number of
processes usually neglected in potential model calculations of
NN--bremsstrahlung is investigated. In particular, we consider the
--excitation pole contributions related to the one--pion and one--rho
exchange and in addition include the exchange contributions induced by the
radiative decays. The contributions are
calculated from relativistic Born amplitudes fitted to --production and
absorption data in the energy range up to 1 GeV and then used to supplement
potential model and soft photon calculations for nucleon--nucleon
bremsstrahlung. The effects on --observables, although moderate in
general, are found to be important in some kinematic domains.Comment: 15 pages in LaTex, using Revtex, 6 figures as uufile'd, compressed
Postscript file included, TRIUMF preprint TRI-PP-94-9
Dynamical model for Pion - Nucleon Bremsstrahlung
A dynamical model based on effective Lagrangians is proposed to describe the
bremsstrahlung reaction at low energies. The
degrees of freedom are incorporated in a way consistent with
both, electromagnetic gauge invariance and invariance under contact
transformations. The model also includes the initial and final state
rescattering of hadrons via a T-matrix with off-shell effects. The differential cross sections are calculated using three different
T-matrix models and the results are compared with the soft photon
approximation, and with experimental data. The aim of this analysis is to test
the off-shell behavior of the different T-matrices under consideration.Comment: 16 pages, latex, 6 eps figures. Accepted for publication in Physical
Review
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