6,778 research outputs found
The Nucleon-Nucleon Potential in the Chromo-Dielectric Soliton Model: Statics
We study the N-N interaction in the framework of the chromo-dielectric
soliton model. Here, the long-range parts of the nonabelian gluon
self-interactions are assumed to give rise to a color-dielectric function which
is parameterized in terms of an effective scalar background field. The
six-quark system is confined in a deformed mean field through an effective
non-linear interaction between the quarks and the scalar field. The CDM is
covariant, respects chiral invariance, leads to absolute color confinement and
is free of the spurious long range Van der Waals forces which trouble
non-relativistic investigations employing a confining potential. Six-quark
molecular-type configurations are generated as a function of deformation and
their energies are evaluated in a coupled channel analysis. By using molecular
states instead of cluster model wave functions, all important six-quark
configurations are properly taken into account. The corresponding Hamiltonian
includes the effective interaction between the quarks and the scalar background
field and quark-quark interactions generated through one gluon exchange treated
in Coulomb gauge. When evaluating the gluonic propagators, the inhomogeneity
and deformation of the dielectric medium are taken into account. Results for
the adiabatic nucleon-nucleon potential are presented, and the various
contributions are discussed. Finally, an outlook is given on how, in the next
stage of our investigation, the dynamical effects will be incorporated by
employing the generator coordinate method.Comment: 43 pages, REVTeX file followed by 11 uuencoded PostScript figures,
DOE/ER/40427-02-N9
Quantum Coulomb systems : screening, recombination and van der Waals forces
The study of quantum Coulomb systems at equilibrium is important for
understanding properties of matter in many physical situations. Screening,
recombination and van der Waals forces are basic phenomena which result from
the interplay of Coulomb interactions, collective effects and quantum
mechanics. Those phenomena are introduced in the first part of this lecture,
through various physical examples. Their treatment within mean-field theories
and phenomenological approaches is also exposed, while related predictions are
discussed. This sheds light on fundamental issues, which must be analyzed
without any \textsl{a priori} approximations or modelizations. The second part
of this lecture is precisely devoted to the presentation of various exact
results for the quantum proton-electron hydrogen plasma. Such results are
derived within the Screened Cluster Representation, which is constructed by
combining the path integral representation of the Coulomb gas with Mayer-like
diagrammatical techniques. They illustrate the breakdown of Debye exponential
screening by quantum fluctuations, as well as the emergence of familiar
chemical species in suitable low-temperature and low-density limits. Also, the
amplitude of van der Waals forces is shown to be reduced by free charges
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