New results on J/  +  - and J/ e + e -

1. New results on J/+- and J/e+e- • Significant advances on both analysis during summer • Today: proposal for Hard Probes 2010 talks • Integrated cross sections, central and forward rapidity • d/dpT and d/dy • Comparisons with other LHC experiments and with calculations E. Scomparin for the MUON and JPSI2EE groups – P.F. 6/10/2010

2. Reminder: already approved preliminary results • In the muon sector: • Differential y and pT distributions in arbitrary units • Evaluation of pT2 and pT ..plus various performance plots for both e+e- and +- analyses

3. J/+- : event sample and cuts • Analysis results are based on the • LHC10c1 period (runs 118903-120242)  low intensity • LHC10d1 period (runs 122372-124608)  high intensity • LHC10d2-b period (runs 125628-126424)  low intensity c1:fraction of LHC10c1 period with high trigger efficiency d1: fraction of LHC10d with high intensity d2-b: fraction of LHC10d with low intensity and good tracking performance Only runs surviving QA checks (on the stability of tracking/trigger performances) are used for analysis “default cuts” : 1 muon matching the trigger, at least 1 vertex reconstructed in the SPD, 17.5 < Rabs < 80 cm Analysis performed in the rapidity ranges 2.5<y<4, 2.7<y<3.8

4. J/+- : invariant mass spectra • Total signal: ~ 1.9 103 J/ • As an example, for LHC10d1 (2.5<y<4) : NA60 CrystalBall • Both fits nicely describe the data (NA60: 2 ~0.7, CB: 2 ~1) • ’ mass and width are linked to the J/ ones

5. J/  +- : acceptance  efficiency • Based on realistic simulations performed separately for each period • Realistic y and pT J/ distributions pT  CDF extrapolation y  CEM calculation A   LHC10c1 LHC10d1 LHC10d2-b • The d sub-periods have almost identical A  

6. J/  +- : normalization • Normalization calculated through CINT1B evaluated from V0AND • From the average of the low intensity runs (both c and d periods) • we get V0AND/CINT1B = 0.873 • WithV0AND = 62.3 mb we get CINT1B = 71.4 mb • The integrated luminosity, for the runs selected for analysis, are: • LHC10c1 2 nb-1 • LHc10d1 6.9 nb-1 • LHC10d2-b 4.7 nb-1 13.6 nb-1

7. J/  +- : cross section • We choose as a reference the • crystal ball fit, also used by CMS • and LHCb • Cross sections per unit rapidity • in good agreement (3% difference) LHCb 3% • Results obtained in each period are in agreement within errors The result is in reasonable agreement with the LHCb value: LHCb 2.5<y<4 7.65  0.19 b

8. J/  +- : syst. errors on cross section Uncertainty on signal extraction: CB vs NA60 shapes + influence of tails and background shape 7.5% +2.0 % -1.3 % +1.4 % -1.3 % pT y pT and y shapes used in the MC 4% Trigger efficiency Tracking efficiency 2% Normalization 10% 13.5% Syst. errors combined +12.0 % -20.7 % Polarization (helicity frame)

9. J/  +- : cross section • Our proposed value for the J/ cross section in 2.5<y<4 is which can be compared with the corresponding LHCb result • In the restricted rapidity range 2.7<y<3.8 we get

10. J/  +- : y distribution • ICHEP release was based on the restricted 2.7<y<3.8 range • (some oscillations in dN/dy were observed at the edges of the • rapidity domain) • Yesterday’s discussion inside PWG3: try to perform updated • analysis in 2.5<y<4 No oscillations in d/dy at the edges Adopt 2.5<y<4 in the following

11. Invariant mass spectra, 2.5<y<4 -3.7<y<-3.4 -4<y<-3.7 -3.1<y<-2.8 -2.8<y<-2.5 -3.4<y<-3.1

12. J/  +- : d/dy ALICE preliminary ALICE preliminary

13. J/  +- : pT distribution • Fit, for each pT bin, the invariant mass distributions • pT bins: 0-1, 1-2, 2-3, 3-4, 4-5, 5-6, 6-8 GeV/c (2.5<y<4) ALICE performance

14. Differential cross section snd comparison with LHC-b ALICE preliminary Check: d/dydpT insensitive to the chosen rapidity range Very good agreement with LHCb!

15. Systematic errors Polarization-related  ALICE preliminary ALICE preliminary Point-to-point systematic errors

16. J/  +- : comparison with CEM • Calculation recently sent by Ramona • By her own admission forward region more delicate than central ALICE preliminary N.B.: calculation for prompt J/, i.e. direct +c and ’ feedback

17. J/e+e- : event sample and cuts • Results given for two (partially overlapping) samples: • LHC10b + LHC10c • LHC10b + LHC10c + LHC10d

18. J/e+e- : invariant mass spectra • Periods b+c (pass2)+d (pass1+tender), NJ/ = 199  25 • Like-sign normalized to the region at the right of the J/ peak

19. J/e+e- :acceptance  efficiency • LHC10e2 +LHC10f7 productions

20. J/e+e- :acceptance  efficiency • Combining previous slide’s factors:

21. J/  e+e- : syst. errors on cross section • “Conservative” estimate (18%) proposed for cross section release

22. J/  e+e- : cross section results Periods b+c+d

23. J/  e+e- : cross section results Periods b+c MNR calculation with ad-hoc scaling

24. Splitting muons in rapidity bins

25. Energy dependence • bb cross section times B.R. BJ/ • Factor 2 lacking ? LHCb value could also be plotted

26. Another possible plot Remove, for simplicity, the bb curve

27. J/  e+e- : pT distributions

28. J/  e+e- : pT distribution b+c+d, SPDany • Comparison with CMS encouraging • Efficiency correction not done period by period: arbitrary scale • probably safer

29. Conclusions • Very significant improvements in both electron and muon analyses • Based on the results shown today we would like to propose as • preliminary plots/quantities for the Hard Probes presentations • Integrated inclusive J/ cross sections for |y|<0.88 and 2.5<y<4 • Differential cross sections in pT and y for 2.5<y<4, compared • with LHCb results and CEM calculations • pT distribution (not absolutely normalized) for |y|<0.88, • shape comparison with CMS

30. ALICE preliminary ALICE preliminary

31. 2.7<y<3.8 ALICE performance

32. ALICE preliminary ALICE preliminary

33. x = 3.0  0.4 pT2 = 8.4 +1.1-0.9 (GeV/c)2