scholarly journals Effect of Meson Exchange Currents on Charge Form Factors of the Three-Nucleon System

1980 ◽  
Vol 63 (6) ◽  
pp. 2127-2132 ◽  
Author(s):  
T. Katayama ◽  
Y. Akaishi ◽  
H. Tanaka
Keyword(s):  
Form Factors ◽  
Meson Exchange ◽  
Nucleon System ◽  
Charge Form ◽  
Meson Exchange Currents

The role of electromagnetic form factors in meson exchange currents

1988 ◽  
Vol 331 (4) ◽  
pp. 509-518 ◽  
Author(s):  
S. K. Singh ◽  
W. Leidemann ◽  
H. Arenh�vel
Keyword(s):  
Form Factors ◽  
Meson Exchange ◽  
Electromagnetic Form Factors ◽  
Meson Exchange Currents

Magnetic form factors for a trinucleon system using different meson exchange nucleon–nucleon interactions

1993 ◽  
Vol 71 (9-10) ◽  
pp. 455-461
Author(s):  
Ahmed Osman ◽  
M. Zaky ◽  
M. A. Allam
Keyword(s):  
Experimental Data ◽  
Momentum Transfer ◽  
Form Factors ◽  
Nucleon Nucleon ◽  
Meson Exchange ◽  
Current Conservation ◽  
Meson Theory ◽  
Transfer Region ◽  
Magnetic Form Factors ◽  
Meson Exchange Currents

The magnetic form factors for the 3He and 3H nuclei have been calculated for different values of momentum transfer. The three-nucleon ground-state wave function is expressed in momentum space and is obtained from the solution of the Faddeev equations with realistic two-body potentials. The potential used is taken from the meson theory to include different meson-exchange contributions satisfying the requirements of current conservation. The different meson-exchange currents and their contributions to the trinucleon magnetic form factors are calculated. The virtual Δ-excitation and the meson–nucleon vertices form factors are included in the 3He and 3H magnetic-form-factors calculations. The present results show the importance of the higher momentum transfer region as being a good source of information to the short-range processes in the nuclear medium. Our results for the 3He and 3H magnetic form factors are in good agreements with the experimental data. The inclusion of the ρ and ω meson exchanges improves the agreement between positions of the minima of the magnetic form factors predicted and the experimental data.

scholarly journals A Six-Quark Dressed-Bag Description of np→dγ Radiative Capture

2003 ◽  
Vol 12 (04) ◽  
pp. 449-478 ◽  
Author(s):  
M. M. Kaskulov ◽  
P. Grabmayr ◽  
V. I. Kukulin
Keyword(s):  
Cross Sections ◽  
Radiative Capture ◽  
Form Factors ◽  
Nucleon Nucleon ◽  
Pion Exchange ◽  
Exchange Current ◽  
Meson Exchange ◽  
Capture Process ◽  
Nucleon Nucleon Interaction ◽  
Meson Exchange Currents

The radiative capture process np→dγ is considered within the framework of a recently developed six-quark dressed-bag model for the nucleon-nucleon interaction. The calculations presented here include both the nucleon current and the meson-exchange current contributions. The latter uses short-range hadronic form factors for the pion exchange currents consistent with the soft cut-off parameter ΛπNN from the NN-potential. Contributions of the pion exchange current and Δ-isobar current to the total cross-section still cannot explain the discrepancy between the theoretical and experimental cross-sections. Possibilities for new types of meson exchange currents associated with chiral fields inside multi-quark dressed-bag states in nuclei are discussed.

Isovector excitation of stretched states in nuclei: effects of meson exchange currents, unbound wave functions, and knockout exchange amplitudes on the extraction of particle–hole strengths

1987 ◽  
Vol 65 (6) ◽  
pp. 666-676 ◽  
Author(s):  
R. A. Lindgren ◽  
M. Leuschner ◽  
B. L. Clausen ◽  
R. J. Peterson ◽  
M. A. Plum ◽  
...  
Keyword(s):  
Electron Scattering ◽  
Transition Amplitude ◽  
Form Factors ◽  
Wave Functions ◽  
Meson Exchange ◽  
Valence Nucleon ◽  
Radial Wave ◽  
Model Calculations ◽  
Nucleus Scattering ◽  
Meson Exchange Currents

It is well known that the strength for excitations of [Formula: see text] high spin, stretched states observed via inelastic scattering, is generally much smaller than that predicted by spherical shell-model calculations. In addition, results obtained from electromagnetic and hadronic studies have discrepancies at the 20% level. For us to gain a better understanding of reduced magnetic strength in electron scattering and hopefully close the gap between experiment and theory, calculations of the electron-scattering form factors have been performed including the effects due to meson exchange currents in the transition amplitude and the effects due to unbound wave functions for the valence nucleon. The effect of the meson exchange-current contributions is to uniformly enhance the form factors near the first maximum, resulting in a 16 to 20% further reduction of the stretched particle–hole strength. The effect due to the radial wave functions deduced from Woods–Saxon potentials in which the nucleon is not bound is to reduce the form factors, thereby resulting in an increase in the spectroscopic strength. As regards the comparison of results obtained with electromagnetic and hadronic probes, the implied sensitivity to higher order current and spin–current transition densities associated with the nonlocality due to the tensor knockout exchange amplitudes in nucleon–nucleus scattering is considered explicitly. It is found that the simplest correspondence between electron and nucleon–nucleus scattering is preserved for isovector excitations but not for isoscalar excitations under the usual assumptions for the tensor interaction. It is clear that precise comparisons between experiment and theory (or between probes) cannot be made unless these and related effects are consistently included.

scholarly journals Isoscalar meson exchange currents and the deuteron form factors

1993 ◽  
Vol 71 (16) ◽  
pp. 2555-2558 ◽  
Author(s):  
Hiroshi Ito ◽  
Franz Gross
Keyword(s):  
Form Factors ◽  
Meson Exchange ◽  
Meson Exchange Currents
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