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Title: Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates

Abstract

The effects of mode-mode and isospin-isospin correlations on nonequilibrium chiral dynamics are investigated by using the method of the time-dependent variational approach with squeezed states as trial states. Our numerical simulations show that large domains of the disoriented chiral condensate (DCC) are formed because of the combined effect of the mode-mode and isospin-isospin correlations. Moreover, it is found that, when the mode-mode correlation is included, the DCC domain formation is accompanied by the amplification of the quantum fluctuation, which implies the squeezing of the state. However, neither the DCC domain formation nor the amplification of the quantum fluctuation is observed if only the isospin-isospin correlation is included. This suggests that the mode-mode coupling plays a key role in the DCC domain formation.

Authors:
 [1];  [2];  [1];  [3]
  1. Department of Physics, Osaka University, Toyonaka 560-0043 (Japan)
  2. (RCNP), Osaka University, Ibaraki 567-0047 (Japan)
  3. Physics Division, Faculty of Science, Kochi University, Kochi 780-8520 (Japan)
Publication Date:
OSTI Identifier:
20771491
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.73.045212; (c) 2006 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; BOSE-EINSTEIN CONDENSATION; CHIRALITY; COMPUTERIZED SIMULATION; CORRELATIONS; COUPLING; FLUCTUATIONS; HEAVY ION REACTIONS; ISOSPIN; PHASE TRANSFORMATIONS; TIME DEPENDENCE; VARIATIONAL METHODS

Citation Formats

Ikezi, N., Research Center for Nuclear Physics, Asakawa, M., and Tsue, Y. Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.045212.
Ikezi, N., Research Center for Nuclear Physics, Asakawa, M., & Tsue, Y. Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates. United States. doi:10.1103/PhysRevC.73.045212.
Ikezi, N., Research Center for Nuclear Physics, Asakawa, M., and Tsue, Y. Sat . "Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates". United States. doi:10.1103/PhysRevC.73.045212.
@article{osti_20771491,
title = {Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates},
author = {Ikezi, N. and Research Center for Nuclear Physics and Asakawa, M. and Tsue, Y.},
abstractNote = {The effects of mode-mode and isospin-isospin correlations on nonequilibrium chiral dynamics are investigated by using the method of the time-dependent variational approach with squeezed states as trial states. Our numerical simulations show that large domains of the disoriented chiral condensate (DCC) are formed because of the combined effect of the mode-mode and isospin-isospin correlations. Moreover, it is found that, when the mode-mode correlation is included, the DCC domain formation is accompanied by the amplification of the quantum fluctuation, which implies the squeezing of the state. However, neither the DCC domain formation nor the amplification of the quantum fluctuation is observed if only the isospin-isospin correlation is included. This suggests that the mode-mode coupling plays a key role in the DCC domain formation.},
doi = {10.1103/PhysRevC.73.045212},
journal = {Physical Review. C, Nuclear Physics},
number = 4,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • We discuss the effect of the chiral anomaly as a possible mechanism for triggering the formation of domains of disoriented chiral condensate (DCC) in relativistic heavy ion collisions. The anomalous {pi}{sup 0}{r_arrow}2{gamma} coupling and the strong, Lorentz contracted electromagnetic fields of the heavy ions combine to produce the {open_quotes}anomaly kick{close_quotes} to the field configuration of the neutral pion field. We implement the effect of the anomaly kick in our numerical simulation of the linear sigma model in a schematic way which preserves its characteristic features: the effect is coherent over a large region of space but is opposite in signmore » above and below the ion scattering plane. We demonstrate by detailed simulations with longitudinal expansion that the DCC domain formation is dramatically enhanced by the anomaly kick in spite of its small absolute magnitude. We examine the behavior of various physical quantities such as pion fields, the axial vector currents, and their correlation functions. Our results also provide useful insight into the mechanism and properties of DCC domain formation, in general. Finally, we discuss some experimental observables which can signal the anomaly induced formation of DCC. {copyright} {ital 1998} {ital The American Physical Society}« less
  • Two- and three-pion correlations are investigated in cases when a disoriented chiral condensate (DCC) occurs. A chaoticity and weight factor are used as measures of two- and three-pion correlations, and the various models for the DCC are investigated. Some models are found to yield the chaoticity and weight factor in a reasonable agreement with recent experimental data.
  • If coherent states describe the disoriented chiral condensates (DCC`s), many states of different chiral orientations should equally contribute to a given hadronic process. However, in the classical field description, we ignore the interference between the different DCC amplitudes. It results in a disregard of isospin invariance. We examine quantitatively how good this approximation is for the DCC`s of a typical size.
  • Isospin density and thermal corrections for several condensates are discussed, at the one-loop level, in the frame of chiral dynamics with pionic degrees of freedom. The evolution of such objects gives an additional insight into the condensed-pion phase transition that occurs basically when vertical bar {mu}{sub I} vertical bar>m{sub {pi}}, vertical bar {mu}{sub I} vertical bar being the isospin chemical potential. Calculations are done in both phases, showing a good agreement with lattice results for such condensates.
  • The nonequilibrium evolution of the hadronic plasma produced in a high energy heavy ion collision is studied in the O(4) linear [sigma] model to leading order in a large [ital N] expansion. Starting from an approximate equilibrium configuration at an initial proper time [tau] in the disordered phase we study the transition to the ordered broken symmetry phase as the system expands and cools. We give results for the proper time evolution of the effective pion mass, the order parameter [l angle][sigma][r angle] as well as for the pion two point correlation function. We study the phase space of initialmore » conditions that lead to instabilities (exponentially growing long wavelength modes) which can lead to disoriented chiral condensates. We find that as a consequence of the strong self-coupling instabilities can exist for proper times that are at most 3 fm/[ital c] and lead to condensate regions that do not contain large number of particles.« less