Hadronic Scatterings of Charm Mesons and Enhancement of Intermediate Mass Dileptons

Heavy quark production in hadronic reactions is reasonably well described by perturbative QCD. However, in heavy ion collisions, final-state interactions may affect the spectra of produced heavy mesons. At the Relativistic Heavy Ion Collider (RHIC), a dense partonic system, often called the quark gluon plasma (QGP), is expected to be formed at the early stage. Since the QGP may induce a strong radiative energy loss of the produced heavy quarks, a change in the spectra of heavy meson observables could provide us information on the properties of the QGP. But interactions between heavy mesons and other hadrons may not be negligible and need to be studied. Such a hadronic modification of the charm spectra in heavy ion collisions has been recently suggested 1 as a possible explanation for the observed enhancement of dimuons of intermediate masses in the NA50 experiments at the CERN-SPS. Assuming that charm mesons develop a transverse flow due to rescatterings with hadrons, leading to a harder charm meson m⊥ spectra, dimuons from charm meson decays are also found to have a harder p⊥ spectrum. Based on the energy cuts for muons at the NA50 experiment, more dimuons would then be found to have an invariant mass above 1.5 GeV. Another explanation based on dilepton productions from secondary meson-meson interactions has also been proposed . Whether or not charm mesons acquire a transverse flow depends on how strongly charm mesons interact with other hadrons during their propagation through the matter. In this study, we shall evaluate the scattering cross sections of charm mesons with pion, rho, and nucleon, using an effective Lagrangian. The effects of hadronic scatterings on the charm meson transverse momentum spectra and dileptons from charm meson decays are then estimated for heavy ion collisions at CERN-SPS energies.