Improved measurement of the b-anti-b production cross section in 920-GeV fixed-target proton-nucleus collisions.

HERA-B COLLABORATION , H. WAHLBERG

PHYSICAL REVIEW D - PARTICLE AND FILDS

Año: 2006 vol. 73 p. 52005 - 52005

0556-2821

A new measurement of the b-bbar production cross section in 920 GeV proton-nucleus collisions is presented by the HERA-B collaboration. The b-bbar production is tagged via inclusive bottom quark decays into J/psi mesons, by exploiting the longitudinal separation of J/psi->ll decay vertices from the primary proton-nucleus interaction point. Both e+e- and mu+mu- channels are reconstructed, for a total of 83 +- 12 inclusive b->J/psi X events found. The combined analysis yields a b-bbar to prompt J/psi cross section ratio of ${rac{{Deltasigma(bbbar)}}{{Deltasigma_{jpsi}}}} = 0.032pm 0.005 stat pm 0.004 sys$ measured in the x_f acceptance (-0.35 <x_f <0.15), extrapolated to $sigma(bbbar) = 14.9 pm 2.2 stat pm 2.4