Transcript Double J/ψ Production

Double J/ψ Production
Jianguo Bian, Guoming Chen,Jian Wang
IHEP, Beijing
2011 Oct 7
1
1. DATA SAMPLE AND TRIGGER
Data sample
/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 = 2.80 -- 3.35; |y| < 2.4; requires the
presence of a third muon (with no pT or y cuts on that 3rd
muon)
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2. MC SAMPLE AND TRIGGER
MC sample
• private production based on the Color-Singlet Model
(arXiv:0903.0954)
• cross section is 15.5nb for ptJ/ψ<25, |yJ/ψ|<2.4,
• CMSSW_4_2_4_hltpatch1
• event number is 114678 for ptJ/ψ<25, |yJ/ψ|<2.4,
Trigger algorithm
HLT_Dimuon0_Jpsi_Muon_v2_1E33p1E33
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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,
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3. EVENT SELECTION (con't)
 Double J/ψ selection
• the two J/ψ's don't share a common muon track
• minimal |mµµ1-3.097| + |mµµ2-3.097| is required
if number of J/ψ candidates >2,
• µµ1 and µµ2 are sorted by yµµ1 > yµµ2,
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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/ψ
J/ψ1, J/ψ2
gaussian,
gaussian
2
background
background
bac1,bac2
2th poly,
2th poly
3
background
J/ψ
bac3,J/ψ3
2th poly,
gaussian
4
J/ψ
background
J/ψ4, bac4
gaussian,
2th poly
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
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4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)
 2 J/ψ are not required to share a common vertex
2
3
4
jpsi4
jpsi3
jpsi1
1
bac3
bac1
doube J/ψ, i.e. jpsi1jpsi2 = 807±69
jpsi2
bac4
bac2
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4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)
 2 J/ψ are required to share a common vertex with probability >0.001
and pdl <0.02 cm
jpsi3
jpsi1
5
6
7
8
jpsi4
bac3
bac1
doube J/ψ, i.e. jpsi1jpsi2 = 309±39
jpsi2
bac4
bac2
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4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)
 MC sample with vertex fit probability>0.001 and pdl<0.02cm
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10
11 12
jpsi1
jpsi2
doube J/ψ, i.e. jpsi1jpsi2 = 161±13 . Jian Wang will check the sample.
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4. NUMBER OF Double J/ψ From 2 DIMENSION FIT(con't)
 Double J/ψ mass
pp→double J/ψ
fig. 13
black lines: |mµµ1-3.091|<3σ=0.126,
|mµµ2-3.091|<3σ=0.126,
blue lines: sideband
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5. Efficiency and Cross section by MC sample
 From 114678 MC events, we get 161±13 Events (see slide 9)
total efficiency by one step for whole phase space
εtot =(161 ±13) /114678 =(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,
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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)
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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,
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6. CONCLUSION AND TO DO LIST
 conclusion
using HLT_Dimuon0_Jpsi_Muon_v1,v2,v4,v6 to select DJpsi events
from 1969.2/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.
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BACKUP
15
Efficiency from Tag&Probe: MuonID
16
MuonQual
17
MuonL1L2
18
Data: MuonQual
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
0.96±0.01
0.8~1.2
0.98±0.02
0.968±0.009
0.962±0.005
0.97±0.01
1.2~1.6
0.97±0.01
1.00±0.02
0.979±0.005
0.98±0.02
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
1.000±0.001
1.00±0.01
1.00±0.08
eta
pt
19
Data: MuonID
pt
2~4
4~6
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
0.99±0.02
1.00±0.02
0.97±0.06
1.2~1.6
0.96±0.01
1.000±0.005 1.00±0.01
0.99±0.08
1.6~2.1
1.000±0.005 1.00±0.01
1.00±0.02
1.0±0.1
2.1~2.4
1.00±0.01
0.94±0.05
0.3±0.2
eta
1.00±0.05
6~15
15~40
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Data: MuonL1L2
2~4
4~6
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
0.3~0.6
0.45±0.01
0.901±0.006 0.970±0.004 1.000±0.005
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
2.1~2.4
0.63±0.02
0.616±0.001 1.0±0.2
eta
pt
0.66±0.04
6~15
0.83±0.03
15~40
1.00±0.08
1.00±0.10
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Data: MuonL3
Pt
Efficiency
2~5
0.852±0.003
5~7
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
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MC: MuonQual
2~4
4~6
6~15
15~40
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
0.993±0.001
0.6~0.8
1.000±0.001
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
1.0000±0.0004
1.6~2.1
0.995±0.006
1.000±0.001
1.0000±0.0003
1.0000±0.0004
2.1~2.4
1.0000±0.0006
1.0000±0.0005
1.0000±0.0002
1.0000±0.0003
eta
pt
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MC:MuonID
eta
pt
2~4
4~6
6~15
15~40
0.0~0.2
0.741±0.009 0.985±0.002 0.9988±0.00 0.9993±0.00
03
02
0.2~0.3
0.62±0.01
0.3~0.6
0.854±0.006 0.990±0.001 0.9982±0.00 0.9988±0.00
03
02
0.6~0.8
0.833±0.001 0.988±0.001 0.9990±0.00 0.9987±0.00
02
03
0.8~1.2
0.869±0.005 0.989±0.001 0.9987±0.00 0.9984±0.00
02
02
1.2~1.6
0.938±0.002 0.9974±0.00 0.9987±0.00 0.9992±0.00
05
02
02
1.6~2.1
0.991±0.001 0.9975±0.00 0.9989±0.00 0.9991±0.00
05
02
02
2.1~2.4
0.994±0.002 0.9994±0.00 0.9997±0.00 0.9998±0.00
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05
01
01
0.953±0.004 0.9953±0.00 0.9960±0.00
07
07
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
0.913±0.004
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
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MC: MuonL3
Pt
Efficiency
2~5
0.902±0.005
5~7
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
26