Köln 2004 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 24: Electromagnetic and Hadronic Probes III
HK 24.4: Talk
Wednesday, March 10, 2004, 11:45–12:00, B
Finite density QCD sum rules in the large-Nc limit — •Stefan Leupold and Marcus Post — Institut für Theoretische Physik, Universität Giessen, 35392 Giessen, Germany
QCD sum rules are analysed for finite nuclear density for the ρ-meson
channel. On the condensate side in-medium changes can be calculated in the
linear density approximation. On the hadronic side various physical effects
lead to modifications of the current-current correlator, e.g.
(a) changes of the pion cloud of the ρ-meson,
(b) excitation of nucleon-hole states N N−1
and (c) excitation of resonance-hole states R N−1.
In principle, it is complicated to disentangle these effects in sum rule
analyses. It is shown that in the limit of infinitely many colors the
numerically most important in-medium changes of the condensate side remain.
On the other hand, on the hadronic side only the resonance-hole excitations
survive. Assuming that the dominant excitation is the D13(1520) we
determine the coupling constants of the latter with the ρ-nucleon
and the photon-nucleon system. We obtain reasonable agreement with the
experimental situation. In particular, we extract a partial decay width of
the D13 into ρ-N of about 12 MeV.
Work supported by GSI.