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Title: 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:
 [1];  [2];  [3];  [4];  [5]
  1. Instituto de Fisica, Universidade Federal do Rio de Janeiro, C.P. 68.528, 21941-972 Rio de Janeiro, RJ (Brazil)
  2. (Germany)
  3. Gesellschaft fuer Schwerionenforschung, D-64291 Darmstadt (Germany)
  4. Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D-60438 Frankfurt (Germany)
  5. 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 01-10; MASS; NUCLEAR MATTER; NUCLEONS; PARITY; PHASE TRANSFORMATIONS; PIONS; SIGMA MODEL

Citation Formats

Zschiesche, D., Institut fuer Theoretische Physik, J. W. Goethe Universitaet, D-60438 Frankfurt, Tolos, L., Schaffner-Bielich, 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, D-60438 Frankfurt, Tolos, L., Schaffner-Bielich, 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, D-60438 Frankfurt, Tolos, L., Schaffner-Bielich, 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, D-60438 Frankfurt and Tolos, L. and Schaffner-Bielich, 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 two-flavored parity doublet model within the mean-field 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 liquid-gas 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 liquid-gas transition, and approaches zero at higher chemical potential associated with the chiral symmetry restoration. A 'transition' frommore » meson-rich to baryon-rich matter is also discussed.« less
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  • A unified scheme for investigating weak meson--nucleon vertices defining parity-nonconserving 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 so-called ''best values'' for them were chosen in that paper. Continuing these investigations we propose a self-consistent 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 » color interactions. We have obtained h/sub ..pi../ = 1/3h/sup b.v//sub ..pi../ and h/sub rho//sub ,//sub ..omega../ which in th whole agree with h/sup b.v//sub rho/. The values obtained for h/sub M/ are stated to agree with the available experimental data, and some future experiments are discussed.« less
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  • The quark exchange model is a simple realization of an adiabatic approximation to the strong-coupling 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 wave-function antisymmetry when color degrees of freedom are included. To begin with, we have considered one-dimensional 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 » two quarks in the system are clustered into hadrons) and by performing a variational Monte Carlo calculation of the energy to optimize [lambda] for a fixed density. We calculate the [ital q]-[ital q] correlation function as well, and discuss the qualitative differences between the system at low and high density.« less