Search for exclusive free-quark production in e/sup +/e/sup -/ annihilation

The products of e/sup +/e/sup -/ annihilation have been searched at 29-GeV center-of-mass energy for free fractionally charged particles produced in exclusive two-body final states. No evidence for fractionally charged quarks was found and the upper limits on the ratio R/sub q/q-bar = sigma/sub q/q-bar/sigma/sub mumu-bar/ are below 1% for quarks with charges 1/3 e or 2/3 e and masses below about 14 GeV/c/sup 2/. This is the first reported limit for charge 1/3 e. Long-lived fractionally charged leptons are definitely ruled out over a significant range of masses.