Measurement of Open Beauty Production at HERA

Abstract

The first observation of open b production in ep collisions is reported. An event sample containing muons and jets has been selected which is enriched in semileptonic b quark decays. The visible cross section σ(ep -> b \bar{b}X -> μX&#39;) for Q^2 < 1 GeV^2, 0.1 < y < 0.8 is measured to be 0.176+-0.016(stat.)+0.026-0.017(syst.) nb for the muons to be detected in the range 35 deg < θ^μ< 130 deg and \pt^μ> 2.0 GeV in the laboratory frame. The expected visible cross section based on a NLO QCD calculation is 0.104+-0.017 nb. The cross sections for electroproduction with Q^2<1 GeV^2 and photoproduction are derived from the data and found to be σ(ep-> e b\bar{b}X) = 7.1+-0.6(stat.)+1.5-1.3(syst.) nb and σ(γp-> b\bar{b} X) = 111+-10(stat.)+23-20(syst.) at an average <W_{γp}> \sim 180 GeV, respectively.