Charm Estimate from the Dilepton Spectra in Nuclear Collisions

A validity of a recent estimate of an upper limit of charm production in central Pb+Pb collisions at 158 A·GeV is critically discussed. Within a simple model we study properties of the background subtraction procedure used for an extraction of the charm signal from the analysis of dilepton spectra. We demonstrate that a production asymmetry between positively and negatively charged background muons and a large multiplicity of signal pairs leads to biased results. Therefore the applicability of this procedure for the analysis of nucleus–nucleus data should be reconsidered before final conclusions on the upper limit estimate of charm production could be drawn. E–mail: [email protected]–frankfurt.de E–mail: [email protected]