Intermediate mass dilepton spectra and the role of secondary hadronic processes in heavy ion collisions

Jul, 1998
25 pages
Published in:
  • Phys.Rev.C 58 (1998) 2914-2927
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Abstract:
We carry out a study of intermediate-mass (between 1 and 2.5 GeV) dilepton spectra from hadronic interactions in heavy-ion collisions. The processes considered are ππllˉ\pi\pi\to l{\bar l}, πρllˉ\pi\rho\to l{\bar l}, πa1llˉ\pi a_1\to l{\bar l}, πωllˉ\pi\omega\to l{\bar l}, KKˉllˉK{\bar K}\to l{\bar l}, and KKˉ+c.cllˉK{\bar K^*}+c.c \to l{\bar l}. The elementary cross sections for those are obtained from chiral Lagrangians involving pseudoscalar, vector, and axial-vector mesons. The respective electromagnetic form factors are determined by fitting to experimental data for the reverse processes of e+ehadronse^+e^-\to hadrons. Based on this input we calculate cross sections and thermal dilepton emission rates and compare our results with those from other approaches. Finally we use these elementary cross sections with a relativistic transport model and calculate dilepton spectra in S+W collisions at SPS energies. The comparison of our results with experimental data from the HELIOS-3 collaboration indicates the importance of the secondary hadronic contributions to the intermediate-mass dilepton spectra.
  • scattering: heavy ion
  • lepton: pair production
  • mass spectrum: dilepton
  • hadron hadron: exclusive reaction
  • pseudoscalar meson
  • vector meson
  • effective Lagrangian: chiral
  • form factor: electromagnetic
  • electron positron: annihilation
  • hadron: electroproduction