OPEN CHARM CONTRIBUTION TO DILEPTON SPECTRA PRODUCED IN NUCLEAR COLLISIONS AT SPS ENERGIES

Measurements of open charm hadro-production from CERN and Fermilab exp eriments are reviewed, with particular emphasis on the absolute cross sections and on their A and root s dependences. Differential p(T) and x(F) cross sections calculated with the PYTHIA event generator are fou nd to be in reasonable agreement with recent data. The calculations ar e scaled to nucleus-nucleus collisions and the expected lepton pair yi eld is deduced. The charm contribution to the low mass dilepton contin uum observed by the CERES experiment is found to be negligible. In par ticular, it is shown that the observed low mass dilepton excess in S-A u collisions cannot be explained by charm enhancement.