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

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Figure3:Distributionsofthetransversemomentumofa)theelectroncandidateandb)themuoncandidatewithrespecttotheclosestjetforthedataandtheresultsofthe t.Thepointsarethedatawhilethedottedlinerepresentsthebackgroundfromthee+e →q¯q,e+e →τ+τ ,e+e →W+W ande+e →e+e τ+τ processes.Thedashedlinesarethesumofthisback-groundandthelight-quarkcontribution,whilethesolidlinesalsoincludeb-quarkproduction.Thenormalisationfollowsfromthe tdiscussedinthetext.