1. J/ψ→μ+μ- Trigger For the First 1/fb Data
M. Yang G. M. Chen
IHEP Beijing
Sep. 25, 2006

2. Introduction
With the first 1/fb data, it is intended to collect a large amount of:
1) prompt J/ψ to calibrate the detector and to study the polarization;
2) B hadrons contain J/ψ decay to check the performance of the detector; Bs→ J/ψ φ to study CP violation;
And to collect enough Bc to measure it’s mass and life time
They are all low pT stuff, low pT dimuon trigger is needed, but the HLT rates must be within the bandwidth allowed.

3. Dimuon trigger at 2x1033 L1 dimuon trigger threshold: 3GeV
HLT pT threshold
(GeV)
HLT rate
(Hz)
Dimuon isolated
7, 7
4.8 ±0.4
Dimuon relaxed
10, 10
8.6±0.6
(PTDR vol2 Table E12)

4. MC Data Samples
QCD, W+jets, Z+jets: CMS official production with OSCAR ORCA
bbbar→μμ X, ccbar→μμX, B hadrons
decay containing J/ψ →μμ, prompt J/ψ
were produced by FAMOS in Beijing

5. QCD datasets Dataset σ(mb) No. of events jm03b_qcd_0_15 55.22 23999
44999
jm03b_qcd_20_30
89999
jm03b_qcd_30_50
92997
jm03b_qcd_50_80
198993
jm03b_qcd_80_120
90000
jm03b_qcd_120_170
70000
jm03b_qcd_170_230
40000
jm03b_qcd_230_300
2.3855*10-5
20000
jm03b_qcd_300_380
*10-6
243983
jm03b_qcd_380_470
*10-6
5000

6. QCD dimuon efficiency withμPt > 3GeV
Dataset
events
QCD →μ
(eff)²
QCD→μμ
eff
0_15
23999 15
(3.92.0)*10-7
15_20
44999
153
(1.2 0.2)*10-5 1
( 2.2 2.2 )*10-5
20_30
89999
572
(4.0 0.3)*10-5 6
( 6.72.7)*10-5
30_50
92997
1139
(1.5 0.1)*10-4 20
(2.2 0.5)*10-4
50_80
198993
5116
(6.6 0.2)*10-4
158
(7.9 0.6)*10-4
80_120
90000
3878
(1.9 0.1) *10-3
163
(1.8 0.1)*10-3
120_170
70000
4314
(3.8 0.1)*10-3
286
(4.1 0.2)*10-3
170_230
40000
3403
(7.2 0.2)*10-3
276
(7.0 0.4)*10-3
230_300
20000
2125
(1.1 0.0)*10-2
199
(1.0 0.1)*10-2
300_380
243983
33606
(1.9 0.0)*10-2
4051
(1.70.0)*10-2
380_470
5000
774
(2.4 0.2)*10-2
117
( 2.30.2)*10-2

7. Trigger Rate at 1033 μPt >3GeV μPt >4GeV μPt >5GeV
0_15
( 21.511.0)
(11.6 7.2)
( 2.42.1)
(0.9 1.0)
(0.3 0.5)
15_20
( 18.03.0)
( 12.62.3)
(5.4 1.2)
(2.30.6)
(1.0 0.3)
20_30
( 25.71.9)
(18.6 1.9)
( 11.61.3)
( 6.40.6)
(3.1 0.4)
30_50
( 23.41.6)
(18.7 1.6)
(12.3 0.9)
( 7.30.6)
(4.5 0.5)
50_80
( 13.90.4)
(11.3 0.4)
( 8.60.2)
(6.1 0.2)
( 4.00.2)
80_120
( 5.60.3)
(4.7 0.3)
( 3.80.3)
(2.8 0.1)
(2.1 0.1)
120_170
(1.9 0.0)
(1.6 0.5)
( 1.30.0)
(1.0 0.0)
(0.8 0.0)
170_230
(0.7 0.0)
(0.6 0.0)
(0.4 0.0)
(0.3 0.0)
230_300
( 0.20.0)
(0.2 0.0)
(0.1 0.0)
300_380
380_470
(0.0 0.0)
( 0.00.0)
Total
(111 11.7)
( 80.18.0)
(46.3 2.9)
( 27.51.5)
( 16.30.9)

8. Isolation could not separate QCD and B hadron

9. J/ψ mass window can be used to reduce the HLT rates
2 windows :
small [3.0, 3.2] large [2.9, 3.3]

10. Mass of di-muons from QCD

12. QCD J/ψmass window (small) efficiency
Dataset σ(mb) Total No. of events
jm03b_qcd_15_20 → jm03b_qcd_ ,971
No. of events dimuon (μPt>3GeV) within [3.0,3.2] = 64

13. QCD HLT rates with small window at 1033
μPt>3GeV (Hz)
And 3.0<Mass<3.2GeV (Hz)
0_15
( 21.511.0)
( 0.26  0.13)
15_20
( 18.03.0)
(0.22  0.04)
20_30
( 25.71.9)
(0.31  0.02)
30_50
( 23.41.6)
( 0.28  0.02)
50_80
( 13.90.4)
( 0.17  0.00)
80_120
( 5.60.3)
(0.07  0.00)
120_170
(1.9 0.0)
(0.02  0.00)
170_230
(0.7 0.0)
(0.01  0.00)
230_300
(0.3 0.0)
(0.00  0.00)
300_380
(0.1 0.0)
( 0.00  0.00)
380_470
(0.0 0.0)
Total
(111 11.7)
(  0.14)

14. W+jets HLT rates at 1033 μPt>3GeV & 3.0<Mass<3.2 GeV 0_20
(3.318 0.336)*10-5
20_50
(2.142  0.126)*10-5
50_85
(1.554  0.042)*10-5
85_150
(1.428  0.042)*10-5
150_250
(4.62  0.00)*10-6
250_400
(1.554 0.084)*10-6
Total
(9.06  0.01) *10-5 (Hz)

15. Z+jets HLT rates with small window at 1033
μPt>3GeV & 3.0<Mass<3.2 GeV
0_20
(7.58 0.14) *10-5
20_50
(1.67 0.08) *10-5
50_85
(0.59 0.00) *10-5
85_150
(0.27 0.00) *10-5
150_250
(0.08 0.00) *10-5
250_400
(0.03 0.00) *10-5
Total
(1.022  0.16) *10-4 (Hz)

16. Other channels Small window sum 1.55±0.15 Hz
μPt>3GeV & 3.0<Mass<3.2 GeV
bbbar→ μμ+ X
 (Hz)
ccbar→ μμ+ X
 (Hz)
prompt J/ψ → μμ
 (Hz)
B+ → J/ ψ (μμ)+X
 (Hz)
Bs → J/ ψ (μμ)+ X
 (Hz)
B0 → J/ ψ (μμ)+ X
 (Hz)
Λb → J/ ψ (μμ)+X
 (Hz)
Small window sum ±0.15 Hz

17. QCD HLT rates with large window at 1033
Data
μPt>3GeV & 2.9<Mass<3.3GeV
0_15
( 0.36  0.18)
15_20
( 0.30  0.06)
20_30
( 0.43  0.03)
30_50
( 0.39  0.03)
50_80
( 0.23  0.01)
80_120
( 0.10  0.01)
120_170
( 0.03  0.00)
170_230
( 0.01  0.00)
230_300
( 0.00  0.00)
300_380
380_470
Total
(  0.19) (Hz)

18. Large mass window Large window sum 2.14±0.20 Hz Data
μPt>3GeV & 2.9<Mass<3.3GeV
bbbar→ μμ+ X
 (Hz)
ccbar→ μμ+ X
 (Hz)
prompt J/ψ → μμ+ X
 (Hz)
B+ → μμ+X
 (Hz)
Bs → μμ+ X
 (Hz)
B0 → μμ+ X
 (Hz)
Λb → μμ+X
 (Hz)
Total
(  ) (Hz)
Large window sum ±0.20 Hz

19. Preliminary suggestion
Dimuon trigger for the first 1/fb data collection:
L< pT>3GeV
L>1032, pT>7GeV
or pT>3GeV & J/ψ mass window
increasing the trigger rate by about

20. Outlook
Study the J/ψ→μ+μ- trigger with CSA06 data in the CMSSW framework
Consider the trigger efficiency for B hadrons and prompt J/ψ
Consider timing