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

σ(ee → eecc,bb X) pb

10

–

+-–

10

+-

10

1

Figure5:Theopen-charm,upper,andopen-beauty,lower,productioncrosssectionsinphoton-photoncollisionsmeasuredwiththeL3detector.Statisticalandsystematicuncertaintiesareaddedinquadrature.Thedashedlinescorrespondtothedirect-processcontributionandthesolidlinesrepresenttheNLOQCDpredictionforthesumofthedirectandsingle-resolvedprocesses.Thee ectsofadi erentchoiceofthevaluesofthequarkmasses,mcandmb,areillustrated.