Measurement of cross sections for b jet production in events with a Z boson in p(p)over-bar collisions at root s=1.96 TeV

A measurement of the b jet production cross section is presented for events containing a Z boson produced in p (p) over bar collisions at root s = 1.96 TeV, using data corresponding to an integrated luminosity of 2 fb(-1) collected by the CDF II detector at the Tevatron. Z bosons are selected in the electron and muon decay modes. Jets are considered with transverse energy E(T) > 20 GeV and pseudorapidity vertical bar eta vertical bar < 1.5 and are identified as b jets using a secondary vertex algorithm. The ratio of the integrated Z + b jet cross section to the inclusive Z production cross section is measured to be 3.32 +/- 0.53(stat) +/- 0.42(syst) x 10(-3). This ratio is also measured differentially in jet E(T), jet eta, Z-boson transverse momentum, number of jets, and number of b jets. The predictions from leading-order Monte Carlo generators and next-to-leading-order QCD calculations are found to be consistent with the measurements within experimental and theoretical uncertainties.