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

EUROPEANORGANIZATIONFORNUCLEARRESEARCH

CERN-PH-EP/2005-007February23,2005

Measurementofthe

CrossSectionforOpen-BeautyProduction

inPhoton-PhotonCollisionsatLEP

arXiv:hep-ex/0507041v1 9 Jul 2005

TheL3Collaboration

Abstract

Thecrosssectionforopen-beautyproductioninphoton-photoncollisionsismea-suredusingthewholehigh-energyandhigh-luminositydatasamplecollectedbytheL3detectoratLEP.Thiscorrespondsto627pb 1ofintegratedluminosityforelectron-positroncentre-of-massenergiesfrom189GeVto209GeV.Eventscon-tainingbquarksareidenti edthroughtheirsemi-leptonicdecayintoelectronsor

¯crosssectionismeasuredwithinour ducialvolumemuons.Thee+e →e+e bbX

andthenextrapolatedtothefullphasespace.Theseresultsarefoundtobeinsig-ni cantexcesswithrespecttoMonteCarlopredictionsandnext-to-leadingorderQCDcalculations.

SubmittedtoPhys.Lett.B