Preliminary results are presented of the the single inclusive bottom jet cross section for events containg a Z⁰ boson. The jets must have a transverse energy E_T > 20 GeV and pseudoradity | &eta | < 1.5. Jets are measured with a cone algorithm with cone size 0.7. Events are selected for the decay channels Z⁰ &rarr e⁺e^- and Z⁰ &rarr &mu⁺&mu^-. Jets containing a b hadron are indentified by reconstructing a secondary vertex. The measurement is based on 337 pb^-1 for the e decay channel and 324 pb^-1 for the &mu decay channel. The data are unfolded to the hadron level and compared to predictions from PYTHIA and NLO QCD.

The measurement is made by searching for pairs of electrons or muons with an invariant mass consistent with the Z⁰ boson and a jet which contains a reconstructed secondary vertex. Secondary vertices are more often formed in b jets than charm (c) or light jets due to the long lifetimes of b hadrons. The residual light and c quark jets are distinguished from the b jets on the basis of the mass of all charged tracks reconstructed at the secondary vertex; b jets tend to have higher masses than the c or light quark jets.

Invarient mass of di-electron pair eps version of the plot. log eps version of the plot.

Invarient mass of di-muon pair eps version of the plot. log eps version of the plot.

Backgrounds in the electron and muon channels eps version of the plot.

The signed mass at the secondary vertex for tagged jets with E_T > 20 GeV and pseudoradity | &eta | < 1.5. The mass is given a negative sign if L_xy is negative. The background has been subtracted from the data. Also shown is the results of the fit to the data of the Monte Carlo templates. eps version of the plot.

The signed trasverse distance between the secondary vertex and the primary vertex for tagged jets with E_T > 20 GeV and pseudoradity | &eta | < 1.5. .The background has been subtracted from the data. Also shown is the expectation of PYTHIA after each component has been scaled by the factors obtained by the fit to M_SVtx. eps version of the plot.

The transverse momentum of tagged jets with E_T > 20 GeV and pseudoradity | &eta | < 1.5. .The background has been subtracted from the data. Also shown is the expectation of PYTHIA after each component has been scaled by the factors obtained by the fit to M_SVtx. eps version of the plot.

The pseudorapidity of tagged jets with E_T > 20 GeV and pseudoradity | &eta | < 1.5. .The background has been subtracted from the data. Also shown is the expectation of PYTHIA after each component has been scaled by the factors obtained by the fit to M_SVtx. eps version of the plot.

The measured cross section and cross section ratios, compared with PYTH IA and the NLO QCD calculation. eps version of the plot.