| Abstract: | The low mass dimuon spectra collected in p-U collisions by the NA38 experiment significantly exceeds the total cross section
expected from previous analysis, done by other experiments. The ‘excess’ events have a harder distribution than the muon pairs from and Dalitz decays, expected to dominate the mass window 0.4–0.65 GeV/. We conjecture that the excess events may be due to annihilations, negligible at low but made visible by the cut applied in the NA38 data. Taking this assumption to parametrise the p-U spectra, we proceed with the corresponding analysis
of the S-Cu, S-U and Pb-Pb data, collected by the NA38 and NA50 experiments, comparing the measured low mass dimuon spectra
with the ‘expected cocktail’.
Received: 14 July 1999 / Revised version: 3 November 1999 / Published online: 27 January 2000 |
