摘要:

We study the bound states of anti-nucleons emerging from the lower continuum in finite nuclei within the relativistic Hartree approach including the contributions of the Dirac sea to the source terms of the meson fields. The Dirac equation is reduced to two Schro¨dinger-equivalent equations for the nucleon and the anti-nucleon respectively. These two equations are solved simultaneously in an iteration procedure. Numerical results show that the bound levels of anti-nucleons vary drastically when the vacuum contributions are taken into account. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427452

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427453

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Based on the self-consistent chiral symmetric scheme of the SU(2) Nambu-Jona-Lasinio model, the meson effects have been investigated on the chiral symmetry breaking vacuum and chiral symmetry restoration by exactly calculating the next-to-leading (NLO) order Feynman diagrams in the1/Ncexpansion. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427454

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

With the global color symmetry model (GCM) being extended to finite chemical potential, the density dependence of the local and nonlocal two- and four-quark condensates in nuclear matter are investigated. The calculated results indicate that, the quark condensates decrease gradually with the increasing of the nuclear matter density. Nevertheless no sudden change emerges. As a maximal nuclear matter density is reached, the quark condensates vanish. It indicates that the chiral symmetry is restored. Furthermore the nonlocal quark condensates vanish at a smaller nuclear matter density, if the quarks are separated farther away from each other. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427455

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A two-source statistical model of an ideal hadron gas is developed and used to analyze the experimental data on hadron yields and ratios in 158A GeVPb+Pbcollisions. The model results fit to the experimental data very well and provide a reasonable and clear physical picture. The whole particle source is composed of a hot small inner source and a bigger and cooler outer source. Baryons are mostly distributed in the outer source, while almost all anti-baryons are contained in the inner source. The strangeness density is found to be non-zero having opposite signs in the two sources. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427456

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We report on the recent results obtained in QMD calculations of theK+production in heavy ion reactions focusing on the physical conclusions one can draw comparing the simulations with the recent data of the KAOS and FOPI collaboration. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427457

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

By using the Isospin Dependent Quantum Molecular Dynamics Model (IQMD), we show the influence of initial N/Z, isospin symmetry potential and medium correction of two-body cross sections on equilibration in momentum space in intermediate energy heavy ion collisions. By investigating the isospin distribution in emitted nucleons, light charged particles and intermediate mass fragmentations for four mass symmetric and isospin asymmetric96+96systemsRu+Ru,Ru+Zr,Zr+Ru,andZr+Zrat 400 AMeV and 100 AMeV we further study the degree of equilibration with respect to isospin degree of freedom in intermediate energy heavy ion collisions. We also propose the sensitive probes to the degree of equilibration in intermediate energy heavy ion collisions. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427458

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The inclusive light fragment(Z⩽7)yield data inAu+Aureactions, measured by the EOS Collaboration at the LBNL Bevalac, are presented and discussed. For peripheral collisions the measured charge distributions develop progressively according to a power law which can be fitted by a single &tgr; exponent independently of the bombarding energy in the range 250–1200 A MeV. In addition to this universal feature, we observe that the location of the maximum in the individual yields of different charged fragments shift towards lower multiplicity as the fragment charge increases fromZ=3toZ=7.This trend is common to all six measured beam energies. Moments of charge distributions and correlations among different moments are reported. Finally, theTHe,DTthermometer has been constructed for central and peripheral collisions using the double yield ratios ofHeandD,Tprojectile fragments. Themeasurednuclear temperatures are in agreement with experimental findings in other fragmentation reactions. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427459

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Within the framework of an isospin-dependent quantum molecular dynamics (IDQMD) model, we study systematically the isospin dependence of four main categories of collective motions in intermediate energy heavy ion collisions, i.e., the in-plane directed flow, in-plane rotational flow, out-of-plane squeeze-out flow, and radial expansion flow. In particular, the influence of symmetry energy and isospin-dependent nucleon-nucleon cross sections on the isospin dependence of the collective flows is studied. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427460

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Study of nuclear clustering by the use of antisymmetrized molecular dynamics (AMD) is discussed for both nuclear structure problems and nuclear collision problems. AMD enables us to describe both the mean field dynamics and the cluster formation. In the study of nuclear structure of light nuclei up to the neutron dripline, it presents us with a unique theoretical method which can describe both shell model structure and the cluster structure and the structure-change between the two. Capability of treating both the mean field dynamics and the dynamical formation of clusters is especially important in the study of heavy ion collisions at intermediate energies because the reaction process is dominated by various types of fragmentation mechanisms. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427461

出版商:AIP    

年代:1901

数据来源: AIP