This web page summarizes the results for the observation of B_c -> J/&psi &pi and the mass measurement of the B_c meson, based upon approximately 0.8 fb^-1 of data.
The results have been approved as of November 10, 2005.
This result is a separate analysis from earlier work on 0.36 fb^-1 data. This work includes that initial 0.36 fb-1 data set and additional data collected since the beginning of 2005.

Using an unbiased selection with requirements chosen on the basis of enhancing the reference decay, B_u -> J/&psi K, we apply those same requirements to the region of interest in J/&psi &pi. We observe an excess of events attributed to the B_c meson with a significance greater than 6&sigma. We measure the mass of the B_c meson to be:

• Mass(Bc) = 6275.2 ± 4.3 (stat) ± 2.3 (syst) MeV/c²

A two page powerpoint summary can be found here: .ppt.
A web page for the analysis for CDF collaborators only: web page

• Figure 1: B_u mass for Opt A and Opt B selection (.eps) (.gif)
• Figure 2: B_u mass for the full sample (.eps) (.gif)
• Figure 3: B_c mass as data accumulates (.eps) (.gif)
• Figure 4: B_c mass for the full sample in three mass ranges (.eps) (.gif)
• Figure 5: B_c mass for the full sample in the extended search region (.eps) (.gif)


• Figure 6: B_c mass with a binned fit superimposed (.eps) (.gif)
• Figure 7: B_c mass with a binned fit and then background subtracted to count signal and background (.eps) (.gif)
• Figure 8: ToyMC probability distribution supporting >6&sigma significance since our data is at S/sqrt(B)=7.6 (.eps) (.gif)
• Figure 9: B_u mass for different 2005 run ranges (.eps) (.gif)
• Figure 10: Table showing B masses for other B hadrons showing very good agreement as a cross-check (.tex) (.ps) (.gif)
• Figure 11: B_u event-by-event mass difference compared with B mass analysis supporting 0.6 MeV systematic (.eps) (.gif)
• Figure 12: Previously blessed study of momentum scale uncertainty translating into mass uncertainty vs Q value of the decay (.eps) (.gif)