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Constraints on vector mesons with finite momentum in nuclear matter

Authors
Journal
Nuclear Physics A
0375-9474
Publisher
Elsevier
Publication Date
Volume
653
Issue
1
Identifiers
DOI: 10.1016/s0375-9474(99)00171-2
Keywords
  • Intermediate And High Energy Heavy Ion Physics
Disciplines
  • Physics

Abstract

Abstract Using the QCD operator product expansion, we derive the real part of the transverse and longitudinal vector-vector correlation function with the quantum numbers of the ϱ and ω mesons to leading order in density and three-momentum ( q 2 ) for ω 2 → −∞. The operator product expansion provides, through the Borel transformed energy dispersion relation, a model independent constraint for the momentum dependence of the vector-meson spectral density in nuclear matter. Existing model calculations for the dispersion effect of the ϱ, where the vector-meson nucleon scattering amplitude is obtained by resonance saturation in the s-channel, in general violate this constraint. We trace this to an inconsistent choice for the form factor of the ΔNϱ vertex. With a consistent choice, where both the form factor and the coupling constant are obtained from the Bonn potential, the contribution of the Δ is substantially reduced and we find good agreement with the constraint equation. We briefly comment on the implications of our result for attempts to interpret the enhancement of low-mass dileptons in heavy-ion collisions.

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