1. Invariant Mass Calculation J/ψ Rosi Reed 3/5/08

2. Introduction J/ψ is the first excited state of charmonium Rest mass 3.096 Gev/c 2 Full Width 93.4 keV One decay channel is: e + e - –BR 5.94% –Width 5.55 keV J/ ψ Triggers 117705 and 137705 –Run # > 7132061 for full CTB coverage –pp 2006

3. First cuts on dE/dx

4. Gaussian Fits to log(dEdx) TPC Hits 15 TPC Hits 30

5. Invariant Mass Calculation w/Errors Cut log(dEdx>1.25)

6. Invariant Mass Calculation w/Errors TPC Hits > 30 P >2.0, log(dEdx*1e6)>1.24 P >2.5, log(dEdx*1e6)>1.26 P >3.0, log(dEdx*1e6)>1.28 P >4.0, log(dEdx*1e6)>1.31

7. TPC Hits – 30 is too tight

8. Invariant Mass Calculation w/Errors TPC Hits > 23 P >2.0, log(dEdx*1e6)>1.24 P >2.5, log(dEdx*1e6)>1.26 P >3.0, log(dEdx*1e6)>1.28 P >4.0, log(dEdx*1e6)>1.31

9. Invariant Mass Calculation w/Errors TPC Hits > 23 P >1.5, log(dEdx*1e6)>1.2

10. Future Work + Questions Extrapolate track to tower in the EMC –Plot p/E per event –Include cuts based on EMC signal Towers separated by >60 degrees phi p/E for PID? Total E? Inv. Mass calculation has –B = 2*(N++N--)^2 Why is this multiplied by 2? What was the measured number of J/ψ in the pp2006 data set?