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Title: Impact of Four-Quark Condensates on In-Medium Effects of Hadrons

Abstract

Spectral properties of hadrons in nuclear matter are treated in the framework of QCD sum rules. The influence of the ambient strongly interacting medium is encoded in various condensates. Especially, the structure of different four-quark condensates and their density dependencies in light quark systems are exemplified for the {omega} meson and the nucleon.

Authors:
 [1];  [2];  [3];  [1];  [4]
  1. Forschungszentrum Dresden-Rossendorf, PF 510119, 01314 Dresden (Germany)
  2. Institut fuer Theoretische Physik, TU Dresden, 01062 Dresden (Germany)
  3. TU Dresden, Lohrmann-Observatorium, 01062 Dresden (Germany)
  4. (Germany)
Publication Date:
OSTI Identifier:
21056830
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 892; Journal Issue: 1; Conference: QCHS7: 7. conference on quark confinement and the hadron spectrum, Ponta Delgada, Acores (Portugal), 2-7 Sep 2006; Other Information: DOI: 10.1063/1.2714393; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; D QUARKS; NUCLEAR MATTER; NUCLEONS; OMEGA-782 MESONS; QUANTUM CHROMODYNAMICS; QUARK CONDENSATION; STRONG INTERACTIONS; SUM RULES; U QUARKS

Citation Formats

Thomas, R., Hilger, T., Zschocke, S., Kaempfer, B., and Institut fuer Theoretische Physik, TU Dresden, 01062 Dresden. Impact of Four-Quark Condensates on In-Medium Effects of Hadrons. United States: N. p., 2007. Web. doi:10.1063/1.2714393.
Thomas, R., Hilger, T., Zschocke, S., Kaempfer, B., & Institut fuer Theoretische Physik, TU Dresden, 01062 Dresden. Impact of Four-Quark Condensates on In-Medium Effects of Hadrons. United States. doi:10.1063/1.2714393.
Thomas, R., Hilger, T., Zschocke, S., Kaempfer, B., and Institut fuer Theoretische Physik, TU Dresden, 01062 Dresden. Tue . "Impact of Four-Quark Condensates on In-Medium Effects of Hadrons". United States. doi:10.1063/1.2714393.
@article{osti_21056830,
title = {Impact of Four-Quark Condensates on In-Medium Effects of Hadrons},
author = {Thomas, R. and Hilger, T. and Zschocke, S. and Kaempfer, B. and Institut fuer Theoretische Physik, TU Dresden, 01062 Dresden},
abstractNote = {Spectral properties of hadrons in nuclear matter are treated in the framework of QCD sum rules. The influence of the ambient strongly interacting medium is encoded in various condensates. Especially, the structure of different four-quark condensates and their density dependencies in light quark systems are exemplified for the {omega} meson and the nucleon.},
doi = {10.1063/1.2714393},
journal = {AIP Conference Proceedings},
number = 1,
volume = 892,
place = {United States},
year = {Tue Feb 27 00:00:00 EST 2007},
month = {Tue Feb 27 00:00:00 EST 2007}
}
  • Utilizing the QCD sum rule approach to the behavior of the {omega} meson in nuclear matter we derive evidence for in-medium changes of particular four-quark condensates from the recent CB-TAPS experiment for the reaction {gamma}+A{yields}A{sup '}+{omega}({yields}{pi}{sup 0}{gamma}) with A=Nb and LH{sub 2}.
  • We propose an analogue of the familiar gap equation for the case of four-quark condensates at finite temperature. The condensates of interest correspond to scalar, vector, pseudoscalar, axial vector, and tensor Dirac structures. Working with correlators at zero chemical potential without factorization, we arrive at coupled equations for these four-quark condensates and the masses of certain light-quark mesons. We study the temperature dependence of the four-quark condensates and masses; in one of our models, factorization of the four-quark condensates is shown to be increasingly violated as the temperature is increased toward T{sub c}. The 2{sup ++} tensor mesons a{sub 2}(1320)-f{submore » 2}(1270) are identified as especially sensitive probes of the four-quark condensates. (c) 2000 The American Physical Society.« less
  • Recent works concerning QCD sum rules in nuclear matter have provided a new method for the calculation of the nucleon self-energy in matter. The results of that program depend strongly on assumptions made concerning the density dependence of four-quark condensates. If a factorization scheme is used to express the four-quark condensate values in terms of the two-quark condensates, the (Lorentz) scalar self-energy of the nucleon is small. However, if the four-quark condensates have only a weak density dependence, the nucleon scalar self-energy is large and attractive, and is in accordance with Dirac phenomenology. In this paper our goal is tomore » show how the Nambu--Jona-Lasinio model may be used to calculate the density dependence of four-quark condensates. As an elementary example we calculate some of the contributions to a four-quark condensate containing scalar-isoscalar [ital [bar q]q] pairs. These calculations suggest only a very small modification of the value of the scalar-isoscalar condensate in matter relative to the value obtained in the factorization scheme. However, when we continue our study of the correlator of operators with the quantum numbers of the nucleon, we encounter some new and important terms among the four-quark condensates. These have their origin in an exchange process between diquarks in the nucleon and diquarks present in the nucleons of the nuclear medium (nuclear matter). These terms may be taken to represent the effects of diquark condensates'' they are present in nuclear matter. If we use the interpolating field advocated by Ioffe we obtain a correction that eliminates the problematic density dependence of the four-quark condensates described above, if nuclear matter contains a similar amount of scalar ([ital T]=0) diquarks and axial-vector ([ital T]=1) diquarks. We believe that our paper provides increased confidence in the use of QCD sum rules in the study of the properties of hadrons in matter.« less
  • Sum rules are calculated by considering the operator expansion for the correlator of two cureents. (AIP)
  • The magnitudes of gluon and four-quark condensates are found from the analysis of vector mesons consisting of light quarks (the families of {rho} and {omega} mesons) in the three-loops approximation. The QCD model with an infinite number of vector mesons is used to describe the function R(s). This model describes well the experimental function R(s). Polarization operators calculated with this model coincide with the Wilson operator expansion at large Q{sup 2}. The improved perturbative theory, such that the polarization operators have correct analytical properties, is used. The result is <0|({alpha}{sub s}/{pi})G{sup 2}|0>=0.062{+-}0.019 GeV{sup 4}. The electronic widths of {rho}(1450) andmore » {omega}(1420) are calculated.« less