1. Gluon Gluon to jpsi jpsi
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2. Typical Feynman diagrams of pair production in p p collision at leading order in color-singlet scheme
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3. Typical Feynman diagrams of pair production in p p collision at leading order in color-singlet scheme
The generator is on the basis of FDC system(arXiv: hep-ph/ ), and the generator could generate events in color-singlet and –octet scheme, respectively.
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4. Comparison between theoretical cross-section calculations and the results of my generator (see arxiv v3 for mathematica results)
Down limit
(2jpsi)
( )
Theoretical calculations in Mathematica
Generator results
Single-color
Octet-color
5GeV
1.08pb
1.15pb
1.329pb
1.492pb
6GeV
0.37pb
0.74pb
0.402pb
0.908pb
7GeV
0.14pb
0.49pb
0.144pb
0.583pb
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5. Signals
If set the down limit of Pt of double jpsi at 5GeV，because if Pt of jpsi was lower than 5GeV, the c quark fragmentation is not appropriate.
cross-section of single-color model is 1.125pb;
cross-section of octet-color model is 1.131pb.
(10 TeV)
This result has included branching ratio of jpsi to mumu:5.6% for each jpsi
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6. CMSSW_3_1_1, 10 TeV Model Pre-selection Color-singlet (100,000 events)
93030
Color-octet (100,000 events)
88249
Pre-selection: dimuon with different charge, Pt >0.7, |eta|<2.5, invariant mass (3.0, 3.2)
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7. Recomuon Number (trackermuon)
Octet
Singlet
Singlet
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8. Inva_mass fitting 2 Cut the first di-muon mass: 2.9-3.3;
Two vertex fitting, chi-square<100.
Fitting area
6566
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9. (pt<3&&fabs(eta)<1)||(pt<3-(1. 5/0. 2
(pt<3&&fabs(eta)<1)||(pt<3-(1.5/0.2*(fabs(eta)-1))&&fabs(eta)<1.2&&fabs(eta)>1)
||(pt<1.5-(0.8/1.3*(fabs(eta)-1.2))&&fabs(eta)<2.5&&fabs(eta)>1.2))
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10. Muon +track Cut the first di-muon mass: 2.9-3.3;
Two vertex fitting, chi-square<100.
Fitting area
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11. Event selection (logical order)
Select first good jpsi: firstly, I require vertex fitting CL>0.001; then mass window:
Bin according to Pt of first good jpsi:0-6,6-8,8-10, 10-12,12+ or 0-6, 6-8, 8-10, 10+
Require vertex fitting CL of the second muon pair or muon + track > So I can decrease background from mis-pairing.
Fit invariant mass of second particle pair. Only could I attain the event number from fitted invariant mass of second particle pair!!!
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12. Efficiency
The numerator is number of second particle pair after fitting.
The denominator is generated events whose jpsi’s Pt is in responding Pt bin. Because Pt of both jpsi is equal, so I can choose Pt of any jpsi to calculate the denominator.
I should check whether Pt of first jpsi is equal to that of fitted second particle pair.
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13. CMS Meeting 8-20

14. CMS Meeting 8-20

15. Octet MCjpsi Pt Bin:0-6,6-8,8-10,10-13,13+ CMS Meeting 8-20
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16. 0-6
512
6-8
1122
8-10
1290
10-13
1090
13+
1432
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17. 0-6
1920
6-8
3608
8-10
2777
10-13
1284
13+
965
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18. Singlet MCjpsi Pt
Bin: 0-6, 6-8, 8-10, 10+
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19. 1495
1376
698
240
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20. 3621
5133
1614
324
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21. General Efficiency
Trig is efficiency of trigger path to select events.
Final-parti-reco is efficiency of final particles like muon, photon, jet, etc.
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