5,842 research outputs found
Deuteron Compton scattering and electromagnetic polarizabilities of the nucleon
Differential cross section of deuteron Compton scattering has been calculated
using the Bonn NN-potential, a consistent set of meson-exchange currents and
seagulls, and lowest- and higher-order electromagnetic polarizabilities of the
nucleon. Estimates of the polarizabilities of the neutron are obtained from
recent experimental data.Comment: 3 pages, 2 figures, Latex2e with ps fonts. Talk at the FB16
Conference, Taipei, March 6-10, 2000. To appear in proceeding
Nuclear effects in positive pion electroproduction on the deuteron near threshold
Positive pion electroproduction from the deuteron near threshold has been
considered within an approach based on the unitary transformation method. The
gauge independence of the treatment is provided by using an explicitly gauge
independent expression for the reaction amplitude. The results of calculations
for kinematics of the experiments on forward-angle meson
electroproduction accomplished at Saclay and Jefferson Laboratory are discussed
and compared with those given by the impulse approximation. It is shown that
the observed behaviour of the cross sections is in accordance with the
calculations based on the pion-nucleon dynamics. In particular, the pion
production rate suppression in the reaction compared to that
for the one can be due to such ``nuclear medium'' effects as
nucleon motion and binding along with Pauli blocking in the final state.Comment: 15 pages, 8 figure
Structure of the -meson and diamagnetism of the nucleon
The structure of the meson and the diamagnetism of the nucleon are
shown to be topics which are closely related to each other. Arguments are found
that the meson couples to two photons via its non-strange
structure component. This ansatz leads to a quantitative explanation of the
-channel component of the difference of electromagnetic polarizabilities,
(\alpha-\beta)^t(\alpha-\beta)^t_{p,n}=(5\alpha_e g_{\pi MM})/(6\pi^2 m^2_\sigma
f_\pi)=15.310^{-4}{\rm fm}^3(\alpha-\beta)^t_p=15.1\pm 1.3(\alpha-\beta)^t_n=14.8\pm 2.7\pi\pi\sigma(\alpha-\beta)^t_{p,n}=14\pm 2$, what also is in agreement with
the experimental results.Comment: Contribution made by Martin Schumacher to the International Workshop
on the Physics of Excited Baryons, 12 - 15 Oct. 2005, Tallahasse, Florida US
Compton Scattering from the Deuteron and Extracted Neutron Polarizabilities
Differential cross sections for Compton scattering from the deuteron were
measured at MAX-lab for incident photon energies of 55 MeV and 66 MeV at
nominal laboratory angles of , , and . Tagged
photons were scattered from liquid deuterium and detected in three NaI
spectrometers. By comparing the data with theoretical calculations in the
framework of a one-boson-exchange potential model, the sum and difference of
the isospin-averaged nucleon polarizabilities, and (in units of fm),
have been determined. By combining the latter with the global-averaged value
for and using the predictions of the Baldin sum rule for
the sum of the nucleon polarizabilities, we have obtained values for the
neutron electric and magnetic polarizabilities of (total) (model) and (total) (model), respectively.Comment: 4 pages, 2 figures, revtex. The text is substantially revised. The
cross sections are slightly different due to improvements in the analysi
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