Cold, dense nuclear matter in a SU(2) parity doublet model
Abstract
We study dense nuclear matter and the chiral phase transition in a SU(2) parity doublet model at zero temperature. The model is defined by adding the chiral partner of the nucleon, the N{sup '}, to the linear sigma model, treating the mass of the N{sup '} as an unknown free parameter. The parity doublet model gives a reasonable description of the properties of cold nuclear matter, and avoids unphysical behavior present in the standard SU(2) linear sigma model. If the N{sup '} is identified as the N{sup '}(1535), the parity doublet model shows a first order phase transition to a chirally restored phase at large densities, {rho}{approx_equal}10{rho}{sub 0}, defining the transition by the degeneracy of the masses of the nucleon and the N{sup '}. If the mass of the N{sup '} is chosen to be 1.2 GeV, then the critical density of the chiral phase transition is lowered to three times normal nuclear matter density, and for physical values of the pion mass, the first order transition turns into a smooth crossover.
 Authors:
 Instituto de Fisica, Universidade Federal do Rio de Janeiro, C.P. 68.528, 21941972 Rio de Janeiro, RJ (Brazil)
 (Germany)
 Gesellschaft fuer Schwerionenforschung, D64291 Darmstadt (Germany)
 Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D60438 Frankfurt (Germany)
 Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States)
 Publication Date:
 OSTI Identifier:
 20995319
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.055202; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CHIRALITY; DENSITY; GEV RANGE 0110; MASS; NUCLEAR MATTER; NUCLEONS; PARITY; PHASE TRANSFORMATIONS; PIONS; SIGMA MODEL
Citation Formats
Zschiesche, D., Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D60438 Frankfurt, Tolos, L., SchaffnerBielich, Juergen, and Pisarski, Robert D. Cold, dense nuclear matter in a SU(2) parity doublet model. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVC.75.055202.
Zschiesche, D., Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D60438 Frankfurt, Tolos, L., SchaffnerBielich, Juergen, & Pisarski, Robert D. Cold, dense nuclear matter in a SU(2) parity doublet model. United States. doi:10.1103/PHYSREVC.75.055202.
Zschiesche, D., Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D60438 Frankfurt, Tolos, L., SchaffnerBielich, Juergen, and Pisarski, Robert D. Tue .
"Cold, dense nuclear matter in a SU(2) parity doublet model". United States.
doi:10.1103/PHYSREVC.75.055202.
@article{osti_20995319,
title = {Cold, dense nuclear matter in a SU(2) parity doublet model},
author = {Zschiesche, D. and Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D60438 Frankfurt and Tolos, L. and SchaffnerBielich, Juergen and Pisarski, Robert D.},
abstractNote = {We study dense nuclear matter and the chiral phase transition in a SU(2) parity doublet model at zero temperature. The model is defined by adding the chiral partner of the nucleon, the N{sup '}, to the linear sigma model, treating the mass of the N{sup '} as an unknown free parameter. The parity doublet model gives a reasonable description of the properties of cold nuclear matter, and avoids unphysical behavior present in the standard SU(2) linear sigma model. If the N{sup '} is identified as the N{sup '}(1535), the parity doublet model shows a first order phase transition to a chirally restored phase at large densities, {rho}{approx_equal}10{rho}{sub 0}, defining the transition by the degeneracy of the masses of the nucleon and the N{sup '}. If the mass of the N{sup '} is chosen to be 1.2 GeV, then the critical density of the chiral phase transition is lowered to three times normal nuclear matter density, and for physical values of the pion mass, the first order transition turns into a smooth crossover.},
doi = {10.1103/PHYSREVC.75.055202},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}

We study thermodynamics of nuclear matter in a twoflavored parity doublet model within the meanfield approximation. Parameters of the model are chosen to reproduce correctly the properties of the nuclear ground state. The model predicts two phase transitions in nuclear matter, a liquidgas phase transition at normal nuclear density and a chiral transition at higher density. At finite temperature the pion decay constant exhibits a considerable reduction at intermediate values of chemical potential, which is traced back to the presence of the liquidgas transition, and approaches zero at higher chemical potential associated with the chiral symmetry restoration. A 'transition' frommore »

Nuclear matter and neutron stars in a parity doublet model
We investigate the properties of isospinsymmetric nuclear matter and neutron stars in a chiral model approach adopting the SU(2) paritydoublet formulation. This ansatz explicitly incorporates chiral symmetry restoration with the limit of degenerate masses of the nucleons and their parity partners. Instead of searching for an optimized parameter set we explore the general parameter dependence of nuclear matter and star properties in the model. We are able to get a good description of groundstate nuclear matter as well as large values of mass for neutron stars in agreement with observation. 
Formation of paritynonconserving nuclear forces in the standard model SU(2)/sub L/ x U(1) x SU(3)/sub c/
A unified scheme for investigating weak mesonnucleon vertices defining paritynonconserving nuclear forces has been suggested in the paper by Desplanques, Donoghue, Holstein (Ann. Phys. (N. Y.) 124 (1980), 449). Reasonable bounds for the values of constants h/sub M/ were found and the socalled ''best values'' for them were chosen in that paper. Continuing these investigations we propose a selfconsistent approach based on the standard SU(2)/sub L/ x U(1) x SU(3)/sub c/ theory for the calculation of all contributions to h/sub M/. This allows us to analyse the role of each component of the standard model: charged and neutral currents, amore » 
Abnormal dilepton yield from parity breaking in dense nuclear matter
At finite density parity can be spontaneously broken in strong interactions with far reaching implications. In particular, a timedependent pseudoscalar background would modify QED by adding a ChernSimons term to the lagrangian. As a striking consequence we propose a novel explanation for the dilepton excess observed in heavy ion collisions at low invariant masses. The presence of local parity breaking due to a timedependent pseudoscalar condensate substantially modifies the dispersion relation of photons and vector mesons propagating in such a medium, changing the {rho} spectral function and resulting in a potentially large excess of dileptons with respect to the predictionsmore » 
Dynamical color correlations in a SU(2)[sub [ital c]] quark exchange model of nuclear matter
The quark exchange model is a simple realization of an adiabatic approximation to the strongcoupling limit of quantum chromodynamics: the quarks always coalesce into the lowest energy set of flux tubes. Nuclear matter is thus modeled in terms of its quarks. We wish to study the correlations imposed by total wavefunction antisymmetry when color degrees of freedom are included. To begin with, we have considered onedimensional matter with a SU(2) color internal degree of freedom only. We proceed by constructing a totally antisymmetric, color singlet [ital Ansatz] characterized by a variational parameter [lambda] (which describes the length scale over whichmore »