Phi->KK mass

• plot
• The Phi peak was found using ~30K events in the J/Psi dimuon sample. Using the GtrHtf tracking algorithm, two tracks of opposite sign with Pt> 1.5 GeV and abs(dz)< 2cm were used.
• Note the PDG value for the Phi mass is 1019.4 MeV

Lambda->proton-pion mass

• plot
• This plot correspond to approximately 55000 input events, so that the reconstruction rate of lambda's is about 1.6%/event. This rate is almost the same both for generic events in one run (152422) and for dimuon sample collected over a long period. The tracking algorithm used to find this peak is AA.
• Note the PDG value for the Lambda mass is 1115.683 MeV

J/Psi cross sections in bins of rapidity

• plot
• plot comparing to CDF Run 1 results
• documentation
• We have calculated J/psi cross sections in five rapidity bins and for two pt ranges. Calculations are based on 4.7 pb^-1 of data, dimuon triggers, runs 145100 - 153888, processed with the d0reco version p10.15. Medium-medium dimuons were matched to central tracks using Gavin Hasketh's macro. Track reco/matching efficiencies were estimated from the data. Trigger efficiencies were estimated both from the data and using the Level 1 dimuon trigger simulator. Local muon reconstruction efficiency was based on Monte Carlo and scanning results. There is an overall systematic uncertainty that we estimate to be at the 30% level. The absolute normalization is in an excellent agreement with the Run 1 D0 and CDF results.

Average B lifetime

• plot
• documentation on fitting studies
• documentation on how the B lifetime is calculated
• Also see older documentation for other systematic studies performed on the B lifetime.
• The average B lifetime has been measured to be 492 +- 37 microns (statistical only). The full systematic error has not yet been determined. A double gaussian shape is used to describe the background and prompt J/Psi.
• Note the PDG value for the average B lifetime is: 469 microns.

Average B lifetime

• plot
• documentation
• The average B lifetime is consistent with the PDG value of 1.564 E-12 s. Depending on the choice of eta cuts, background shape, etc. the central value of the lifetime value changes. All lifetime values are consistent within statistical error of the PDG value. The full systematic error has not yet been determined so we currently are not quoting a central value, rather stating that the lifetime is consistent with the PDG and continued studies of systematics are ongoing.

J/Psi cross section as a function of eta

• plot
• documentation
• We have calculated J/psi cross sections in five rapidity bins and for two pt ranges. Calculations are based on 4.8 pb^-1 of data, dimuon triggers, runs 145100 - 153888, processed with the d0reco version p10.15. Medium-medium dimuons were matched to central tracks using Gavin Hasketh's macro. Track reco/matching and trigger efficiencies were estimated from the data. Local muon reconstruction efficiency was based on Monte Carlo and scanning results. There is an overall systematic uncertainty that we estimate, by hand waiving arguments, to be at the 30% level. However, we have decided to plot only relative cross sections for different kinematic regions. The absolute normalization (substitute "arbitrary scale" by "nb") is in an excellent agreement with the Run 1 D0 and CDF results.

b jet cross section

• cross section
• ptrel fit
• documentation
• This analysis is done using local muons (i.e., without a central track match). The current large systematics in the MC predictions are dominated by uncertainties in muon p_T resolution, jet energy resolution, and MC statistics. These are all expected to be reduced in the future. From this mu+jet cross section, fits to pt_rel distributions are being used to extract the b-jet cross section as a function of jet E_T. For the Ptrel fit in the above approved result, the b content is 21.5% +- 4.3%. The 4.3% error is from the HMCMLL fit which includes both the data statistics and MC statistics. It does not include systematics due to uncertainties in the shapes beyond statistics. (Note the b content is a function of Jet E_T so the 21.5% b content is only valid for the 20 GeV < ETjet < 25 GeV region). Necessary jet energy scale corrections need to be more fully understood to unfold the b-jet cross section to compare directly to NLO calculations. Studies using global muons (with a central track match) already show improved separation between b-jets and background in pt_rel distributions.

Charged B mass

• plot
• documentation
• The charged B mass was determined from the same sample of events as the average B lifetime. We are specifically searching for B+(-) --> J/Psi K+(-). For events containing a J/Psi (dimuon mass between 2.8-3.3) a third track is required to originate from the same vertex as the J/Psi. The mass of the third track is set to the kaon mass. The mass of the mu+ mu- K+(-) combination is shown. The mean and width of the mass peak is consistent with MC predictions. This is the first fully reconstructed B signal found at D0.

Kshort mass peak with full CFT/SMT stereo tracking

• Data sample/cuts and plots

J/Psi->mu+ mu- mass peak and Upsilon peak with CFT tracking

• See Muon-ID approved plot page: J/Psi and Upsilon

B-ID approved results:

• See B-ID approved plot page: Approved results

Muon + jet cross section.

• Data sample and cuts
• Cross Section Plot
• Pt rel for MC and data
• More explanation from the b-ID Group

J/Psi->mu+ mu- mass peak

• See Muon-ID approved plot page: J/psi->mu mu data
  Detailed information is also available off the above page

Kshort/Lambda mass peak

• Data sample/cuts and plots