[PDF] Three Nucleon Force The Delta Mechanism For Pion Production And Pion Absorption eBook

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Page : 26 pages
File Size : 12,55 MB
Release : 1993
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The description of the three-nucleon system in terms of nucleon and [Delta] degrees of freedom is extended to allow for explicit pion production (absorption) from single dynamic [Delta] de-excitation (excitation) processes. This mechanism yields an energy dependent effective three-body hamiltonean. The Faddeev equations for the trinucleon bound state are solved with a force model that has already been tested in the two-nucleon system above pion-production threshold. The binding energy and other bound state properties are calculated. The contribution to the effective three-nucleon force arising from the pionic degrees of freedom is evaluated. The validity of previous coupled-channel calculations with explicit but stable A isobar components in the wavefunction is studied.

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Page : pages
File Size : 23,5 MB
Release : 1983
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In the deuteron, the simplest pion production mechanism is the quasifree process in which the pion is produced on a single nucleon, with the second nucleon acting as a spectator. More interesting mechanisms, however, are those in which both the nucleons are actively involved, as shown in Figs. 1b to 1d. In addition, there exist higher-order two-nucleon processes involving both ..pi..N and NN rescatterings. At T/sub ..pi../> 250 MeV, there is evidence that the basic production could proceed via intermediate ..pi..N- and ..pi pi..-resonances, including the ..delta..(1232) resonance. Considering the fact that the ..pi..N rescattering can also proceed through the formation of a ..delta..(1232), we then have a situation in which two ..delta..(1232) can be simultaneously present. Recently, G.E. Brown et al. have proposed a double-..delta.. model to explain certain features of pion absorption by nuclei. It seems useful to further examine this mechanism by use of other nuclear reactions, such as the ..pi..−d ..-->.. ..pi ... pi..−nn reaction. In this report, we only briefly describe our calculations of the quasifree process and ..pi.. production followed by ..pi..N rescattering. We have also omitted the distortion of the incoming pion wave. This approximation should not affect our conclusion concerning the relative importance of the two diagrams studied. (WHK).

Author : R.J. Peterson
Publisher : American Institute of Physics
Page : 602 pages
File Size : 49,30 MB
Release : 1988
Category : Science
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Proceedings of the Los Alamos conference held in Aug. 1987. Topics: few-body questions, charge exchange reactions, heavier mesons, low-energy pion reactions, pion absorption, physics in the continuum, nuclear structure, deltas in nuclei. No index. Acidic paper. Annotation copyright Book News, Inc. Portland, Or.

Author : Torleif Erik Oskar Ericson
Publisher : Oxford University Press, USA
Page : 506 pages
File Size : 17,90 MB
Release : 1988
Category : Language Arts & Disciplines
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The pion plays an outstanding role in nuclear physics as a generator of the nuclear force and as an important part of the nuclear many-body problem. At the same time, pion beams are used as probes to explore the nucleus and its interactions. As pion physics has matured over the years, a rich and diverse variety of phenomena has been uncovered. The aim of this book is to examine the underlying physical picture behind these phenomena in a systematic and coherent way. The authors emphasize the interplay between physical concepts and experimental facts more than the formal tools, which are presented in a series of appendices. The book is directed towards advanced students as well as research workers.

Author : M J Vicente-vacas
Publisher : World Scientific
Page : 730 pages
File Size : 48,43 MB
Release : 1992-03-27
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ISBN : 9814555916

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The proceedings reflect the recent experimental and theoretical progress in pion nuclear physics in topics like pionic atoms, pion absorption, charge exchange, (π, 2π), and others involving pions in nuclei using different probes, as electron photons or heavy ions. Related topics on chiral symmetry, low energy πN and (γ, π⁰) and quark degrees of freedom are also addressed.

Author : Declan Persram
Publisher :
Page : 124 pages
File Size : 40,39 MB
Release : 1996
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"We present a calculation of $ Delta$ production cross section in the one-boson-exchange model for the reaction $NN to N Delta.$ Our calculation is in quantitative agreement with a previous calculation by Huber and Aichelin (1). The effect of the $NN to N Delta$ anisotropic differential cross section on $ pi$ production in Au + Au collisions at a kinetic energy of $1{GeV over A}$ is studied. We find that there is no large effect on the final $ pi$ transverse momentum spectra." --