Measurement of the $b\overline{b}$ production cross section in 920 GeV fixed-target proton-nucleus collisions

Abstract.

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