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 $\sigma$-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 ($\approx$ 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 $U$ 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