Measurement of the b Jet Production Cross Section in Events with a W± Boson

 
Christopher Neu, Evelyn Thomson, Joel Heinrich (Penn) mail us


&sigma b-jets (W+b-jets) &sdot BR(W &rarr l v) = 2.74 ± 0.27 (stat) ± 0.42(syst) pb
in events with a pT > 20 GeV/c, |&eta| < 1.1 electron or muon,
a pT > 25 GeV/c neutrino, and
1 or 2 ET > 20 GeV/c2, |&eta| < 2.0 jets regardless of species.
 

Links to pertinent information:
  • Abstract
  • Public note
  • Plots
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     Abstract
     
    The b jet production cross section is measured for events with a W boson in ppbar collisions at 1.96 TeV. The data were collected using the Collider Detector at Fermilab (CDF) experiment during Run II of the Fermilab Tevatron collider. W + b jet events are selected by requiring a high pT central electron or muon, large MET and one or two high ET central jets; vertex information are used from the jets to select the subset that are consistent with originating from b quark production. For this analysis a new operating point for the widely used CDF vertex tagger was implemented that has significantly increased b purity over standard methods. Assuming standard model cross sections for top and diboson processes, the b jet production cross section for events with a leptonically decaying W boson is measured to be 2.74 +- 0.27 (stat) +- 0.42(syst) pb. The measurement is compared to several available theoretical predictions. This measured cross section provides a data-driven measurement of a difficult-to-predict background for single top and Higgs searches.
     
     
     Plots and Tables
     
     
    		 Vertex mass fit for the tagged jets in the selected sample.
     

     
    		 Vertex mass shapes from simulated jets for three species: b, c and light flavor (u/d/s).
     

     
    		Calibration of b shape using data. Same plots, one without the residual.
     

     
    		Data-to-simulation comparison for tagged jet ET and eta.
     

     
    		Data-to-simulation comparison for tagged jet total track multiplicity (left) and vertex track multiplicity (right).
     

     
    		Data-to-simulation comparison for vertex displacement from primary in transverse plane L_2d (left) and its significance (right).
     

     
    		 Summary of the impact of systematic errors on the measured b jet cross section.
     

     
    		 Yields of tagged jets in 1.9/fb of data.
     

    Christopher Neu
    Last modified: Wed May 21 15:33:35 CDT 2008