1. Jianguo Bian, Guoming Chen,Jian Wang IHEP, Beijing 2011 Oct 7
Double J/ψ Production
Jianguo Bian, Guoming Chen,Jian Wang
IHEP, Beijing
2011 Oct 7

2. Data sample Trigger algorithm 1. DATA SAMPLE AND TRIGGER
/MuOnia/Run2011A-PromptReco-v4/RECO,
luminosity = 913.8/pb.
/MuOnia/Run2011A-PromptReco-v5/RECO,
luminosity = 399.6/pb
/MuOnia/Run2011A-PromptReco-v6/RECO,
luminosity = 655.8/pb
total luminosity=1969.2/pb
Trigger algorithm
HLT_Dimuon0_Jpsi_Muon_v1, v2, v4,v6
Dimuon cuts: mass = ; |y| < 2.4; requires the presence of a third muon (with no pT or y cuts on that 3rd muon)

3. MC sample Trigger algorithm 2. MC SAMPLE AND TRIGGER
private production based on the Color-Singlet Model
(arXiv: )
cross section is 15.5nb for ptJ/ψ<25, |yJ/ψ|<2.4,
CMSSW_4_2_4_hltpatch1
event number is for ptJ/ψ<25, |yJ/ψ|<2.4,
Trigger algorithm
HLT_Dimuon0_Jpsi_Muon_v2_1E33p1E33

4. 3. EVENT SELECTION Moun selction global or tracker muons
muon pT > 0.8 GeV, 2.2<|η|<2.4
muon pT > 1.0 GeV, 1.3<|η|<2.2
muon pT > 2.4 GeV, |η|<1.3
inner track χ2/dof < 1.8,
∆R(μrec,μL3)<0.1
number of muons >=4.
J/ψ selction
two muons have opposite charge,
J/ψ rapidity 0<|y|<2.4,
J/ψ pt <25,
vertex fit probability > 0.001,

5. 3. EVENT SELECTION (con't)
Double J/ψ selection
the two J/ψ's don't share a common muon track
minimal |mµµ | + |mµµ | is required
if number of J/ψ candidates >2,
µµ1 and µµ2 are sorted by yµµ1 > yµµ2,

6. 4. NUMBER OF Double J/ψ From 2 DIMENSION FIT
4 components in 2 dimension fit
µµ_1
µµ_2
label
fit function 1
J/ψ
J/ψ1, J/ψ2
gaussian,
gaussian 2
background
bac1,bac2
2th poly,
2th poly 3
bac3,J/ψ3
2th poly, gaussian 4
J/ψ4, bac4
when fitting, it is assumed that J/ψ1, J/ψ2,J/ψ3, J/ψ4 have same gaussian parameters. bac1,bac3 have same poly parameters, so do bac2,bac4.
µµ_1

7. 4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)1 2 3 4
2 J/ψ are not required to share a common vertex
jpsi4
jpsi3
bac3
jpsi1
jpsi2
bac4
bac1
bac2
Djpsi_Run2011A_PromptReco_165071_175770_Apr_11_v7_n6_c2.ps
doube J/ψ, i.e. jpsi1jpsi2 = 807±69

8. 4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)5 6 7 8
2 J/ψ are required to share a common vertex with probability >0.001
and pdl <0.02 cm
jpsi3
jpsi4
jpsi1
bac3
jpsi2
bac4
bac1
bac2
Djpsi_Run2011A_PromptReco_165071_175770_Apr_11_v7_n6_c2.ps
doube J/ψ, i.e. jpsi1jpsi2 = 309±39

9. 4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)9 10 11 12
MC sample with vertex fit probability>0.001 and pdl<0.02cm
jpsi2
jpsi1
Djpsi_Run2011A_PromptReco_DiJPsi_MC_1E33_Apr_11_v7_n6_c2.ps
doube J/ψ, i.e. jpsi1jpsi2 = 161±13 . Jian Wang will check the sample.

10. 4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)
Double J/ψ mass
pp→double J/ψ
fig. 13
black lines: |mµµ |<3σ=0.126,
|mµµ |<3σ=0.126,
blue lines: sideband

11. 5. Efficiency and Cross section by MC sample
From MC events, we get 161±13 Events (see slide 9)
total efficiency by one step for whole phase space
εtot =(161 ±13) / =(1.4 ± 0.11)E-3.
Cross section=Nevents/ (εtotLumi)/fr2(J/ψ→μμ)=31.9±4.1nb
Theory predicts 15.5nb for ptJpsi<25,|yJpsi|<2.4,

12. 6. Efficiency and Cross section by tag-prob
the efficiency to find one muon: εmuon=εid εqual εtrig
where εtrig= εL1L2 εL3
the efficiency to find 4 muons is
ε4muon= εμ1id εμ1qual εμ2id εμ2qual εμ3id εμ3qual εμ4id εμ4qual
* ε3muontrig,
ε3muontrig is HLT_Dimuon0_Jpsi_Muon trigger efficiency for 4 muon,
ε3muontrig= εμ1trig εμ2trig(1-εμ3trig)εμ4trig εψ1mass
+ εμ1trig εμ2trigεμ3trig(1-εμ4trig) εψ1mass
+ εμ3trig εμ4trig(1-εμ1trig)εμ2trig εψ2mass
+ εμ3trig εμ4trigεμ1trig(1-εμ2trig) εψ2mass
+ εμ1trig εμ2trigεμ3trigεμ4trig (εψ1mass+ εψ2mass- εψ1mass*εψ2mass),
where εψ1mass= εψ1mass(pt,y) ≈1,εψ2mass= εψ2mass(pt,y ) ≈1
to consider ψ mass=(2.80,3.35)

13. 6. Efficiency and Cross section by tag-prob(con’t)
From MC simulation get a total efficiency
ε total= Nfit-after-all-cuts/Ngenerated (see slide 9)
Then get difference between data and MC as the correction factor with Tag&Probe
C= εdata_4moun/ εMC-4moun= 0.776±0.006
(It should be checked using larger MC sample)
The corrected efficiency εtotal×C could be considered as the real efficiency.
Final cross section is
cs=(31.9 ±4.1)/0.776=(41.1 ±5.3)nb for
ptJpsi<25,|yJpsi|<2.4,

14. 6. CONCLUSION AND TO DO LIST
using HLT_Dimuon0_Jpsi_Muon_v1,v2,v4,v6 to select DJpsi events
from /pb data collected by CMS, we obtain
nDJpsi=309±39 for ptJpsi<25,|yJpsi|<2.4,
cross section = 41.1±5.3nb.
theoretical cross section is 15.5 nb.
to do list
produce more MC events to check C factor
reduce background
calculate differential cross section
Calculate the system uncertainty.

15. BACKUP

16. Efficiency from Tag&Probe: MuonID

17. MuonQual

18. MuonL1L2

19. Data: MuonQual pt eta 2~4 4~6 6~15 15~40 0.0~0.2 0.97±0.02 0.97±0.01
0.962±0.005
0.96±0.02
0.2~0.3
1.000±0.007
0.98±0.01
0.966±0.008
0.98±0.02
0.3~0.6
0.958±0.008
0.973±0.008
0.972±0.004
0.990±0.006
0.6~0.8
0.99±0.02
0.96±0.01
0.972±0.005
0.8~1.2
0.968±0.009
1.2~1.6
1.00±0.02
0.979±0.005
1.6~2.1
0.999±0.006
0.985±0.007
0.9883±0.0001
1.000±0.001
2.1~2.4
1.00±0.05
1.00±0.01
1.00±0.08 pt
eta

20. Data: MuonID
2~4
4~6
6~15
15~40
0.0~0.2
0.83±0.02
1.000±0.003
1.000±0.008
0.96±0.06
0.2~0.3
0.67±0.03
0.95±0.02
0.99±0.02
1.00±0.05
0.3~0.6
0.86±0.02
0.99±0.01
0.98±0.01
0.97±0.06
0.6~0.8
0.85±0.02
1.000±0.005
1.00±0.01
1.00±0.03
0.8~1.2
0.94±0.02
1.00±0.02
1.2~1.6
0.96±0.01
0.99±0.08
1.6~2.1
1.0±0.1
2.1~2.4
0.94±0.05
0.3±0.2 pt
eta

21. Data: MuonL1L2
2~4
4~6
6~15
15~40
0.0~0.2
0.38±0.01
0.852±0.008
0.968±0.005
1.000±0.005
0.2~0.3
0.22±0.02
0.63±0.02
0.83±0.03
1.00±0.08
0.3~0.6
0.45±0.01
0.901±0.006
0.970±0.004
0.6~0.8
0.39±0.02
0.892±0.008
0.974±0.005
1.000±0.006
0.8~1.2
0.39±0.01
0.888±0.006
0.953±0.005
0.98±0.01
1.2~1.6
0.543±0.007
0.948±0.006
0.952±0.008
0.97±0.02
1.6~2.1
0.536±0.010
0.84±0.01
0.85±0.02
1.00±0.10
2.1~2.4
0.66±0.04
0.616±0.001
1.0±0.2 pt
eta

22. Pt Efficiency 2~5 5~7 7~9 9~15 15~25 25~40 Data: MuonL3 0.852±0.003
0.987±0.001
7~9
0.996±0.001
9~15
0.995±0.001
15~25
0.992±0.003
25~40
0.98±0.01

23. MC: MuonQual 2~4 4~6 6~15 15~40 eta pt 0.0~0.2 0.97±0.01 0.980±0.007
0.985±0.003
0.993±0.001
0.2~0.3
1.00±0.01
1.0000±0.0004
0.993±0.004
0.988±0.003
0.3~0.6
1.000±0.001
0.984±0.005
0.9875±0.0008
0.6~0.8
0.991±0.005
0.987±0.003
0.995±0.002
0.8~1.2
0.98±0.02
0.978±0.004
0.986±0.002
0.997±0.001
1.2~1.6
0.996±0.001
0.997±0.004
0.998±0.001
1.6~2.1
0.995±0.006
1.0000±0.0003
2.1~2.4
1.0000±0.0006
1.0000±0.0005
1.0000±0.0002
eta pt

24. MC:MuonID
2~4
4~6
6~15
15~40
0.0~0.2
0.741±0.009
0.985±0.002
0.9988±0.0003
0.9993±0.0002
0.2~0.3
0.62±0.01
0.953±0.004
0.9953±0.0007
0.9960±0.0007
0.3~0.6
0.854±0.006
0.990±0.001
0.9982±0.0003
0.9988±0.0002
0.6~0.8
0.833±0.001
0.988±0.001
0.9990±0.0002
0.9987±0.0003
0.8~1.2
0.869±0.005
0.989±0.001
0.9987±0.0002
0.9984±0.0002
1.2~1.6
0.938±0.002
0.9974±0.0005
0.9992±0.0002
1.6~2.1
0.991±0.001
0.9975±0.0005
0.9989±0.0002
0.9991±0.0002
2.1~2.4
0.994±0.002
0.9994±0.0005
0.9997±0.0001
0.9998±0.0001 pt
eta

25. MC:MuonL1L2
2~4
4~6
6~15
15~40
0.0~0.2
0.48±0.01
0.913±0.004
0.976±0.001
0.982±0.001
0.2~0.3
0.33±0.02
0.759±0.008
0.878±0.003
0.887±0.004
0.3~0.6
0.542±0.009
0.936±0.003
0.9794±0.0008
0.981±0.001
0.6~0.8
0.51±0.01
0.978±0.001
0.984±0.001
0.8~1.2
0.42±0.02
0.893±0.003
0.930±0.001
0.904±0.002
1.2~1.6
0.568±0.005
0.935±0.002
0.954±0.001
0.946±0.001
1.6~2.1
0.6±0.3
0.809±0.004
0.814±0.002
0.782±0.003
2.1~2.4
0.553±0.010
0.69±0.01
0.706±0.006
0.702±0.007

26. Pt Efficiency 2~5 5~7 7~9 9~15 15~25 25~40 MC: MuonL3 0.902±0.005
0.991±0.002
7~9
0.9986±0.0006
9~15
0.9995±0.0002
15~25
0.9983±0.0004
25~40
0.9992±0.0004