Final-state interaction and screening have a great influence on qqˉ​
production cross sections, which are important quantities in many problems in
quark-gluon plasma physics. They lead to an enhancement of the cross section
for a qqˉ​ color-singlet state and a suppression for a color-octet state.
The effects are large near the production threshold. The presence of screening
gives rise to resonances for qqˉ​ production just above the threshold at
specific plasma temperatures. These resonances, especially ccˉ and bbˉ resonances, may be utilized to search for the quark-gluon plasma by
studying the temperature dependence of heavy-quark pair production just above
the threshold.Comment: 12 pages (Latex), 6 figures. Invited talk presented at Strangeness'96
Meeting, Budapest, May 1996. To be published in "Heavy-Ion Physics