We have performed a search for B_c->J/&psi &mu X in 360 pb^-1 of exclusive J/&psi data from Run II. We have identified and estimated several sources of background in the J/&psi+muon mass window of 4.0-6.0 GeV/c², including decay-in-flight and punch-through of pions, kaons and protons, tri-muons arising from the fragmentation of bb pairs, and fake J/&psi together with a third muon.

• Our J/&psi+muon sample of B_c candidates has 106 events with a background of 46.0± 7.3 events.

• The hypothesis that the observed sample can be accounted for by the background is rejected at the level of 5.2 standard deviations.

• The cross-section times branching ratio for B_c->J/&psi &mu &nu relative to B^±->J/&psi K^± is measured and found to be 0.245± 0.045(stat.)± 0.066(syst.)+0.080-0.032(life.) for the case where the B p_T is greater than 6.0 GeV/c.

Here is a complete version of the results: html, ps.

Below are the eps versions of all figures meant for downloads.

• Event Selection Plots
• Figure 1 - Fitted J/&psi Mass
• Figure 2a - J/&psi+Track Mass Distribution
• Figure 2b - J/&psi+&mu Mass Distribution
• Figure 3 - Fitted B± Mass
• Figure 4 - J/&psi+&mu Mass for Generated Bc


• Fake Muon Estimate Plots
• Figure 5a - Third Track dE/dx, 3-3.5 GeV/c
• Figure 5b - Third Track dE/dx, 3.5-4 GeV/c
• Figure 5c - Third Track dE/dx, 4-4.5 GeV/c
• Figure 5d - Third Track dE/dx, 4.5-5 GeV/c
• Figure 6 - Third Track TOF, 2-3 GeV/c
• Figure 7 - Third Track Particle ID Fractions
• Figure 8a - D0 Mass for K- Daughters
• Figure 8b - D0 Mass for K+ Daughters
• Figure 8c - D0 Mass for &pi Daughters
• Figure 8d - D0 Mass for K- Daughters with &mu Match
• Figure 8e - D0 Mass for K+ Daughters with &mu Match
• Figure 8f - D0 Mass for &pi Daughters with &mu Match
• Figure 9 - Fake &mu Probablilities for &pi/K/p
• Figure 15a - D0 Mass for K- Daughters (BGen)
• Figure 15b - D0 Mass for K+ Daughters (BGen)
• Figure 15c - D0 Mass for &pi Daughters (BGen)
• Figure 15d - D0 Mass for K- Daughters with &mu Match (BGen)
• Figure 15e - D0 Mass for K+ Daughters with &mu Match (BGen)
• Figure 15f - D0 Mass for &pi Daughters with &mu Match (BGen)
• Figure 16a - dE/dx Seperation for &pi/K/p
• Figure 16b - TOF Seperation for &pi/K/p
• Figure 17 - 2D TOF vs. dE/dx Fits for Third Track, 2.0-2.8 GeV/c


• Same Sign Muon Study Plots
• Figure 18 - Same Sign &mu&mu Mass Distributions, Data and Predicted Fake &mu
• Figure 19 - Opposite and Same Sign &mu&mu Mass Distribtions, Data and Predicted


• bb Estimate Plots
• Figure 10a - J/&psi&mu &Delta&phi for Pythia Flavor Creation
• Figure 10b - J/&psi&mu &Delta&phi for Pythia Flavor Excitation
• Figure 10c - J/&psi&mu &Delta&phi for Pythia Gluon Splitting
• Figure 11a - J/&psi&mu &Delta&phi for Fake &mu
• Figure 11b - J/&psi&mu &Delta&phi for Fake J/&psi
• Figure 11c - J/&psi&mu &Delta&phi for Fake &mu/Fake J/&psi
• Figure 11d - J/&psi&mu &Delta&phi for BGen Bc
• Figure 12 - Fitted J/&psi&mu &Delta&phi for Data
• Figure 20a - Vertex J/&psi&mu Mass Distribution, Data and Predicted
• Figure 20b - Unvertexed J/&psi&mu Mass Distribution, Data and Predicted
• Figure 21a - Vertex J/&psi&mu Mass Distribution for &Delta&phi>&pi/2, Data and Predicted
• Figure 21b - Unvertex J/&psi&mu Mass Distribution for &Delta&phi>&pi/2, Data and Predicted


• Fake J/&psi Estimate Plots
• Figure 13 - Fake J/&psi Candidates, J/&psi and J/&psi&mu Mass


• Total Background and Signal Plots
• Figure 14a - J/&psi&mu Mass Distributions of Backgrounds
• Figure 14b - J/&psi&mu Mass Distributions of Data, Total Background