19,847 research outputs found
Study of the vacuum matrix element of products of parafields
We study the vacuum matrix elements of products of parafields using graphical
and combinatorial methods.Comment: 15 pages, 4 figures. Figures were omitted in the first versio
Quantum Vacuum in Hot Nuclear Matter - A Nonperturbative Treatment
We derive the equation of state for hot nuclear matter using Walecka model in
a nonperturbative formalism. We include here the vacuum polarisation effects
arising from the nucleon and scalar mesons through a realignment of the vacuum.
A ground state structure with baryon-antibaryon condensates yields the results
obtained through the relativistic Hartree approximation (RHA) of summing
baryonic tadpole diagrams. Generalization of such a state to include the
quantum effects for the scalar meson fields through the -meson
condensates amounts to summing over a class of multiloop diagrams. The
techniques of thermofield dynamics (TFD) method are used for the finite
temperature and finite density calculations. The in-medium nucleon and sigma
meson masses are also calculated in a self consistent manner. We examine the
liquid-gas phase transition at low temperatures ( 20 MeV), as well as
apply the formalism to high temperatures to examine for a possible chiral
symmetry restoration phase transition.Comment: 23 pages with 9 figure
Vacuum polarization effects in hyperon rich dense matter -- a nonperturbative treatment
We derive the equation of state (EOS) for electrically charge neutral dense
matter using Quantum Hadrodynamics (QHD) model. This is carried out in a
nonperturbative manner including quantum corrections for baryons through a
realignment of vacuum with baryon-antibaryon condensates. This yields the
results of relativistic Hartree approximation of summing over baryonic tadpole
diagrams. The quantum corrections from the scalar meson is also taken into
account in a similar way. This leads to a softening of the equation of state
for the hyperonic matter. The formalism also allows us to do a self consistent
calculation of the in-medium sigma meson mass. The effects of such quantum
corrections on the composition of charge neutral dense matter is considered.
The effect of the resulting EOS on the structure of the neutron stars is also
studied.Comment: 26 pages, Latex (ReVTeX style
Spin-Charge Decoupling and Orthofermi Quantum Statistics
Currently Gutzwiller projection technique and nested Bethe ansatz are two
main methods used to handle electronic systems in the infinity limit. We
demonstrate that these two approaches describe two distinct physical systems.
In the nested Bethe ansatz solutions, there is a decoupling between the spin
and charge degrees of freedom. Such a decoupling is absent in the Gutzwiller
projection technique. Whereas in the Gutzwiller approach, the usual
antisymmetry of space and spin coordinates is maintained, we show that the
Bethe ansatz wave function is compatible with a new form of quantum statistics,
viz., orthofermi statistics. In this statistics, the wave function is
antisymmetric in spatial coordinates alone. This feature ultimately leads to
spin-charge decoupling.Comment: 12 pages, LaTex Journal_ref: A slightly abridged version of this
paper has appeared as a brief report in Phys. Rev. B, Vol. 63, 132405 (2001
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