ACCIARRI, M (reprint author), IST NAZL FIS NUCL, VIA CELORIA 16, I-20133 MILAN, ITALY.
The production of B* mesons in Z decays has been measured at LEP with the L3 detector. A sample of Z --> b ($) over bar b events was obtained by tagging muons in 1.6 million hadronic Z decays collected in 1991, 1992 and 1993. A signal with a peak value of E(y) = 46.3+/-1.9 (stat) MeV in the B rest frame energy spectrum was interpreted to come from the decay B* --> gamma B. The inclusive production ratio of B* mesons relative to B mesons was determined from a fit to the spectrum to be N-B*/(N-B* + N-B) = 0.76+/-0.08+/-0.06, where the first error is statistical and the second is systematic.