[PDF] Chiral Perturbation Theory Calculation Of Pion Production In Nucleon Nucleon Collisions eBook

Author :
Publisher :
Page : 40 pages
File Size : 16,31 MB
Release : 1991
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ISBN :

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I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons,?N scattering and the?-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.

Author : Hartmut Machner
Publisher : World Scientific
Page : 618 pages
File Size : 20,31 MB
Release : 1995-05-31
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ISBN : 9814549169

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The investigation of hadronic and nuclear probes with protons and electrons in the energy range of a few GeV is of great importance for the understanding of the properties of nucleons and mesons as well as of their interaction. Experimental results from studies with these beams provide the basis for the development and the tests of theoretical approaches in the energy regime of non-perturbative QCD. They can also clarify the effect of the nuclear medium on elementary reactions. The conference has reviewed the present status of this field of research. The topics have beenThe conference topics comprised investigations near energy thresholds in the tradition of the conferences on Particle Production near Threshold in Nashville, IN, USA, 1990, and Uppsala, Sweden, 1992.

Author : National Aeronaut Administration (Nasa)
Publisher : Createspace Independent Publishing Platform
Page : 58 pages
File Size : 17,1 MB
Release : 2018-07-10
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ISBN : 9781722685447

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The effects of pion (PI) production are expected to play an important role in radiation exposures in the upper atmosphere or on the Martian surface. Nuclear databases for describing pion production are developed for radiation transport codes to support these studies. We analyze the secondary energy spectrum of pions produced in nucleon-nucleon (NN) collisions in the relativistic one-pion exchange model. Parametric formulas of the isospin cross sections for one-pion production channels are discussed and are used to renormalize the model spectrum. Energy spectra for the deuteron related channels (NN yields dPi) are also described. Cucinotta, Franics A. and Wilson, John W. and Norbury, John W. Langley Research Center...