Measurement of the bb̄ production cross section in 920 GeV fixed-target proton-nucleus collisions: The HERA - B collaboration

Abstract

Using the HERA - B detector, the bb̄ production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The bb̄ production was tagged via inclusive bottom quark decays into J/ψ by exploiting the longitudinal separation of J/ψ → l+l- decay vertices from the primary proton-nucleus interaction. Both e+e- and μ+μ- channels have been reconstructed and the combined analysis yields the cross section σ(bb̄) = 32-12+14 (stat)-7+6(sys) nb/nucleon.