Abstract submitted to the
         International Europhysics Conference on High Energy Physics
                  July 12 - 18, 2001, Budapest, Hungary
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       Beauty photoproduction in the muon semi-leptonic decay mode at HERA

                    
                               ZEUS Collaboration





                                    Abstract


     The production of beauty quarks in the photoproduction process e^+p ->
     muon^{\pm} + dijet + X for photon virtuality Q^2 < 1 GeV^2 has been 
     studied with the ZEUS detector at HERA using an integrated luminosity 
     of 38 pb^{-1}. Events with a muon and at least two jets with large 
     transverse energies were selected and the fraction of beauty quarks 
     in the data was determined using the transverse momentum of the muon 
     relative to the axis of the closest jet. Beauty differential cross 
     sections were compared to leading-order parton-shower Monte Carlo 
     models and next-to-leading-order perturbative QCD calculations.