Measurement of the Bc+→J/ψμ+ν relative cross section using the complete CDF dataset
Turgun Nigmanov and Paul Shepard
University of Pittsburgh

This web page summarizes the results of the ratio of the production cross section times branching fraction of Bc+→J/ψ μ+ν relative to B+→J/ψK+:


for pT(B)>6 GeV/c and the rapidity range of |y|<0.6. The measurement is done with exclusive J/ψ→μ+μ- trigger using the full CDF run II dataset, which for this measurement has an intergrated luminosity of (8.7±0.5)fb-1.

The results have been approved by B Physics Group Meeting as of February 28, 2014.

A more detailed description of the results can be found here



The invariant mass distributions of the Bc+→J/ψ μ+ν candidate events with the a Monte Carlo simulated signal sample and the calculated backgrounds superimposed (.eps .jpg) . The backgrounds includes the misidentified muon (green), the misidentified J/ψ (dark blue), the bb backgrounds (yellow) and the other Bc+ decay modes (pink). The Bc+ experimental excess shown as the Bc+ Monte Carlo (light blue).




The summary of the Bc+→J/ψμ+ν candidate events, the various backgrounds, the total backgrounds and the Bc+ experimental excess are shown for three mass regions: 3-4 GeV/c2, 4-6 GeV/c2 (the signal region) and 6-10 GeV/c2 (.eps .jpg). The Bc+ Monte Carlo is normalized to the experimental excess within the signal mass region. One might expect that the experimental Bc+ excess in the non-signal region should be consistent with the Monte Carlo. The deviations from expectations are 1.1±12.0 within 3-4 GeV/c2 and 18.1±18.3 within 6-10 GeV/c2.




Systematic uncertainties in the Bc+→J/ψ μ+ decay channel backgrounds (.eps .jpg).




Systematic uncertainties in the relative efficiency (Δεrel) (.eps .jpg)




Systematic uncertainties in the relative cross section times branching fraction (.eps .jpg)




Result for the ratio Bc+ production cross section times the branching fraction to J/ψμ+ν over B+ production cross section times the branching fraction to J/ψK+. The result is given for pT(B)>6 GeV/c and |y|<0.6 (.eps .jpg)



Our early using 1 fb-1 of data with the Bc+→J/ψμ+ν decay channel measurement public web page is here
Below are the eps and jpeg versions of figures and tables meant for download.

  • Figure 1: The ratio of Bc+ to B+ yields versus the dataset section number (.eps) (.jpg)
  • Figure 2: The invariant mass of the Bc+→J/ψμ+ν candidate events using the full CDF dataset (.eps) (.jpg)
  • Figure 3: The invariant mass of the misidentified J/ψ background (J/ψsideμ+ system) (.eps) (.jpg)
  • Figure 4: The invariant mass of the (J/ψTrack) system. This sample is an input to calculate the misidentified muon background (.eps) (.jpg)
  • Figure 5: Hadron to muon misidentified probabilities versus hadron pT. Used to calculate the misidentified muon background (.eps) (.jpg)
  • Figure 6: The fraction of muon tagged events outside of the Do mass peak (.eps) (.jpg)
  • Figure 7: The fit of the dE/dx responses for K tracks from B+→J/ψK+ decays with Gamma distribution (.eps) (.jpg)
  • Figure 8: The distributions of the dE/dx data fitted with two Gamma distributions, one for pions and a second one for the combined K+p (.eps) (.jpg)
  • Figure 9: The p/p fractions in the (J/ψTrack) system (.eps) (.jpg)
  • Figure 10: The Fπ, FK and Fp for the positively charged third tracks from the (J/ψTrack) system (.eps) (.jpg)
  • Figure 11: The Fπ, FK and Fp for the negatively charged third tracks from the (J/ψTrack) system (.eps) (.jpg)
  • Figure 12: The invariant mass of the misidentified muon (black) and the "double fake" (pink) backgrounds (.eps) (.jpg)
  • Figure 13: The Δφ distribution of the (J/ψμ+) pairs, which are not constrained by the vertex (.eps) (.jpg)
  • Figure 14: The Δφ distributions of the three non-bb contributions (.eps) (.jpg)
  • Figure 15: The Δφ distributions of the (J/ψμ+) system where the non-bb contributions are subtracted (.eps) (.jpg)
  • Figure 16: The fit of the Δφ(J/ψμ+) from data using FC (blue) and GS (green) QCD predictions (.eps) (.jpg)
  • Figure 17: The invariant mass distribution of the bb background (.eps) (.jpg)
  • Figure 18: (J/ψμ+) invariant mass from Bc+ decays with backgrounds superimposed. The Monte Carlo simulated events are normalized to the measured experimental excess of Bc+ decays (See Table 1) (.eps) (.jpg)
  • Figure 19: (J/ψK+) invariant mass from B+ decays (.eps) (.jpg)
  • Figure 20: Comparison of the pT((J/ψK+) spectra for data (black) and corrected FONLL model (red) (.eps) (.jpg)
  • Figure 21: Comparison of the pT((J/ψμ+) spectra for data (bullet) and corrected GMVFN model (dashed) (.eps) (.jpg)
  • Table 1: The Bc+→J/ψμ+ν candidate events showing the Bc+ experimental excess and the calculated backgrounds. In the invariant mass distribution in Fig. 18, the Bc+ excess is generated by a Monte Carlo simulation normalized to the experimental excess shown in this table (.eps) (.jpg)
  • Table 2: The systematic uncertainties for the Bc+ →J/ψμ+ decay channel backgrounds. (.eps) (.jpg)
  • Table 3: The systematic uncertainties for the Δεrel (.eps) (.jpg)
  • Table 4: Summary of the systematic uncertainties in the relative cross section times branching fraction (.eps) (.jpg)
  • Table 5: Summary of results (.eps) (.jpg)