Measurement of the bb̄ Cross Section at HERA-B

Abstract

Abstract. The bb production cross section has been measured in collisions of 920 GeV protons off a nuclei target using the HERA-B detector. The identification of bb events was done via inclusive bottom quark decays into J/ψ by exploiting the longitudinal separation of the J/ψ → l + l − decay vertices from the primary proton nucleus interaction, where both the µ + µ − and the e + e − decay channels have been reconstructed. The first measurement, using data collected during a short period in 2000, yields a cross section in the combined analysis of σ (bb) = 32 +14 −12 (stat) +6 −7 (sys) nb/nucleon. On the most recent data samples taken in 2002/3, a much more accurate measurement with the uncertainties reduced to 10 % is expected.

Bottomonium and Drell–Yan production in p–A collisions at 450 GeV

“…Various results on Υ production in proton-induced collisions exist at fixed target and at ISR energies [12][13][14][15][16][17][18][19][20][21][22][23][24][25], but they are usually less precise than the corresponding charmonium results. Up to now, no data are available at 450 GeV ( √ s = 29.1 GeV), and the A-dependence of the production cross-section has only been studied by the E772 experiment [22], at a higher incident energy.…”