The cross section for open-beauty production in photon-photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627/pb of integrated luminosity for electron-positron

Electrons

NbkgNbb¯Nc¯cNuds

χ2/d.o.f.

24.8( xed)172.0±31.0220.5±35.4

.3

0.0+52 0.06.4/6

Table1:Resultsofthe ttothedistributionofthetransversemomentumoftheleptonwithrespecttothenearestjet.The tparametersareconstrainedtobepositive.ThecorrelationbetweenNbb¯andNc¯cis75%.

Uncertaintyoncrosssection(%)

Electrons

10.42.210.08.23.02.01.41.0

18.3

Eventselection

Leptonidenti cationFiducialvolumeJetreconstruction

Massive/masslesscharmTriggere ciency

MonteCarlostatisticsDirect/resolvedratio