摘要:

An extended version of the Nambu‐Jona‐Lasinio (NJL) model is applied to describe both nuclear matter and surface properties of finite nuclei. Several parameter sets are discussed and a comparison of the saturation properties and equation of state (EOS) with the NL3 parametrization of the non‐linear Walecka model is made. The confinement‐deconfinement phase transition and the properties of asymmetric matter are discussed. A full bosonization of the model is performed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570575

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The behavior of &eegr; and &eegr;′ in hot strange quark matter in weak equilibrium with temperature, is investigated within the SU(3) Nambu‐Jona‐Lasinio [NJL] model. Possible manifestations of restoration of symmetries, by temperature or density, in the behavior of &eegr; and &eegr;′ are discussed. The role played by the combined effect of temperature and density in the nature of the phase transition and meson behavior is also analyzed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570576

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The data for⟨pt2⟩(Et)ofJ/&psgr; produced in Pb‐Pb collisions at the CERN‐SPS contain information about when anomalous suppression is active. A general transport equation which describes transverse motion ofJ/&psgr; in the absorptive medium is proposed and solved for a QGP and a comover scenario of suppression. While inconsistencies appear in the QGP, the comover approach accounts for the data fairly well. For central collisions the bulk of anomalous suppression happens rather late, 3–4 fm/cafter the nuclear overlap. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570577

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We discuss rare events in particle production, with an emphasis on theJ/&psgr; suppression in heavy ion and nucleon collisions, and the role of two dimensional continuum percolation. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570578

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We summarize the results of theSU(4) chiral meson Lagrangian approach to the cross section for J/&psgr; breakup by pion impact. The major weakness of this approach is the arbitrariness in the choice of hadronic form factors. We evaluate the dependence of the cross section on the masses of the final D‐meson states and compare the result to a parametrization that has been employed for the study of in‐medium effects on this quantity. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570579

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Elastic virtual photoproduction of charmonia on nucleons is calculated in a parameter free way with the light‐cone dipole formalism and the same input: factorization in impact parameters, light‐cone wave functions for the photons and the charmonia, and the universal phenomenological dipole cross section which is fitted to other data. The charmonium wave functions are calculated with four known realistic potentials, and two models for the dipole cross section are tested. Very good agreement with data for the cross section of charmonium electroproduction is found in a wide range ofsandQ2. Using the ingredients from those calculations we calculate also exclusive electroproduction of charmonia off nuclei. Here new effects become important, (i) color filtering of thecc¯pair on its trajectory through nuclear matter, (ii) dependence on the finite lifetime of thecc¯fluctuation (coherence length) and (iii) gluon shadowing in a nucleus compared to the one in a nucleon. Total coherent and incoherent cross sections for C, Cu and Pb as functions ofsare presented. The results can be tested with future electron‐nucleus colliders or in the peripheral collisions of relativistic heavy ions. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570580

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We use the QCD sum rules to evaluate theD*D&pgr;,DD&rgr; andDDJ/&psgr; form factors as well as theJ/&psgr; &pgr; → open charm cross sections. The form factors are evaluated as a function of the momentumQ2of the off‐shell meson and the cross sections as a function ofs. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570581

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We study meson (&pgr;,&Kgr;) form factors in general, and specialize at a later stage to a specific scheme, namely the quark‐level linear &sgr; model (L&sgr;M). We compute a variety of electromagnetic and weak observables of light mesons, including pion and kaon form factors and charge radii, charged‐pion polarizabilities, semileptonic weak &Kgr;l3decay, semileptonic weak radiative pion and kaon form factors, radiative decays of vector mesons, and nonleptonic weak &Kgr;2&pgr;decay. We find good to very good agreement with experiment of all these predicted observables. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570582

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A causal, non‐Hermitian, renormalizable, local, unitary and Lorentz convariant formulation of Quantum Theory (QT) (= Quantum Mechanics (QM) and Quantum Field Theory (QFT)) is developed which is free of formalistic problems we face in the commonly used Hermitian formulation of QT. Side effects of the new formulation of QT are the derivation of a consistent (anti)causal neutrino Lagrangian, the enrichment of chiral symmetries, the removal of the Dirac sea, the separation of positive and negative energy states including a reformulation of the anti‐particle concept and a critical analysis of the concept of probability currents. In a first step we apply the new formulation of QT to establish a relation between perturbative Quantum Chromodynamics (QCD) and the (axial)vector meson extended Quark‐Level Linear Sigma Model (QLLSM) at high energies. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570583

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a method to evaluate the pion structure functions from a box diagram calculation. Pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The &ggr;*&pgr; →qq¯cross‐section is evaluated and related to the structure functions. We then show that the introduction of non‐perturbative effects, related to the pion size and preserving gauge invariance, provides us with a straighforward relation with the quark distribution. It is predicted that higher‐twist terms become negligible forQ2larger than about 2 GeV2and that quarks in the pion have a momentum fraction smaller than in the proton. We enlarge the discussion concerning this violation of the momentum sum rule, emphasizing that the sum rule is recovered in the chiral limit and also when the finite size condition is not imposed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570584

出版商:AIP    

年代:1903

数据来源: AIP