Update of trigger study for GMSB photons

Shilei Zang

University of Colorado, Boulder

GMSB Meeting, 14th Dec. 2007

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Outline

• Signal efficiency• Background samples processed• Efficiency vs. Rates• Log(eff)/log(b) vs. Cuts• Preliminary results• Backup slides: Eff. vs. Cuts; Rates vs.

Cuts.

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• Bob Hirosky’s GMSB samples at CMSSW_164 are used to estimate signal efficiency.

• I used 10000 GMSB events: 900 GM1b, 800 GM1c, 1800 GM1d, 5900 GM1e, 600 GM1g.

GMSB sample and Background samples

• PreCSA07 (or CSA07) samples are used to estimate the background rates, which includes:

• Photon jets (all pt bin)• QCD jets (all pt bin)• Wenu, Zee, will be included in rate calculation soon.

(since CSA07 Wenu sample is available just in December.)

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HLT paths for photons• L1Match: Reconstructed super-cluster in the ECAL is required to match L1

energy deposit in some eta and phi windows.

• Et : Et of super-cluster in the ECAL is required to exceed a threshold.

• IEcal: ECAL isolation, total Et of all clusters with ΔR<0.3 around the photon candidate, excluding those belonging to the super-cluster itself.

• IHcal: HCAL isolation, total Et of hadron calorimeter towers with ΔR<0.3 around the photon candidate.

• Itrack: Track isolation, number of tracks with Pt>1.5GeV inside a cone ΔR<0.3 of photon candidate.

4 paths with thresholds

Single Photon

Relaxed Single Photon

Double Photon

Relaxed Double Photon

L1 Iso L1 relaxed L1 Iso L1 relaxed

Et (GeV) 30 40 20 20

IEcal 1.5 1.5 2.5 2.5

IHcal(Barrel) 6 6 8 8

IHcal(Endcaps) 4 4 6 6

Itrack 1 1 3 3

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Efficiency(%) vs. HLT paths and modules

Ecal Isolation

Hcal Isolation

Track Isolation

Isolation together

HLT+L1

Single photon 82.7 96.7 84.2 67.35 62.66

Relaxed Single 79.3 94.5 84.0 62.95 62.14

S, RS 81.8 95.1 84.4 65.46 65.00

Double photon 59.9 92.9 97.3 54.08 39.08

S, RS, D 82.3 95.2 89.0 69.78 69.34

Relaxed Double 54.5 86.4 97.1 45.66 44.16

S, RS, D, RD 82.7 95.1 90.0 70.86 70.53

Signal Efficiency (GMSB photons)

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How many events in each background samples do we need to process in the rate calculation

• Suppose the i-th sample has cross section σi ; with a definite integrated luminosity there will be Ni events of i-th sample ; with some cuts we will select ki events; efficiency of cuts on the i-th sample is εi= ki/ Ni.

• Both ki and Ni are Poisson distribution, and independent, so error of εi

is σ(εi)=Sqrt(εi(1+ εi)/ Ni).

• With instant luminosity L, rate of i-th sample is Lσi εi, with an error of Lσi σ(εi).

• To keep a small error of total rate and reduce the number of events to process, we require Lσi σ(εi)= Lσj σ(εj), so

Ni /Nj = (σi / σj)2[εi(1+ εi)]/[εj(1+ εj)].

• Process the i-th sample with small number of events (finally needs to select ~100 events, so the relative error of εi is ~10%) ; roughly determine the efficiency εi with all default HLT paths will use. Then get the ratio of Ni /Nj .

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Background samples processed (1)PhotonJets Cross section

(sigma)Efficiency (eff) (%)

Sigma**2*(1+eff)*eff(10**3 pb**2)

Number of Events processed

0_15 0.17 mb 0 0 500,000

15_20 257 nb 0.064 42,290 50,000

20_30 132 nb 4.698 857,040 606,680

30_50 41 nb 33.6 754,590 386,579

50_80 7.2 nb 46.4 35,210 194,741

80_120 1.3 nb 52.15 1,340 164,000

120_170 275 pb 55.12 64.7 69,993

170_300 87 pb 54.81 6.4 24,993

300_500 8.2 pb 48.65 0.048 15,554

500_7000 0.87 pb 37.49 4E-4 6,666

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Background samples processed (2)QCDJets Cross section

(sigma)Efficiency (eff) (%)

Sigma**2*(1+eff)*eff(10**3 pb**2)

Number of Events processed

0_15 55.2 mb 0 0 295,613

15_20 1.46 mb 2E-4 4,263E6 500,000

20_30 0.63 mb 2.8E-3 11,113E6 2,002,945

30_50 0.163 mb 0.026 6,908E6 1,987,498

50_80 0.0216 mb 0.093 434E6 651,984

80_120 0.00308 mb 0.122 11.57E6 525,594

120_170 494 nb 0.162 395,340 499,389

170_230 101 nb 0.217 22,136 428,888

230_300 24.5 nb 0.303 1,819 172,619

300_380 6.24 nb 0.323 126 82,998

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Background samples processed (3)QCDJets Cross section

(sigma)Efficiency (eff) (%)

Sigma**2*(1+eff)*eff(10**3 pb**2)

Number of Events processed

380_470 1.78 nb 0.375 12 88,086

470_600 683 pb 0.491 2.3 55,000

600_800 204 pb 0.637 0.265 21,974

800_1000 35.1 pb 0.738 9E-3 33,330

1000_1400 10.9 pb 0.830 1E-3 5,299

1400_1800 1.6 pb 1.0 2.6E-5

1800_2200 145 fb 1.2 2.5E-7

2200_2600 23.8 fb

Wenu 7.9 nb Need to process

Zee 0.82 nb

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Efficiency vs. Rates (Single Photon)

• Final Rate is about :

9.4+-0.5, for single photon path.

• HLT study group resut (CMSSW131):

8.4+-0.7.

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Efficiency vs. Rates (Relaxed Single Photon)

• Final Rate is about :

3.0+-0.2, for relaxed single photon path.

• HLT study group resut (CMSSW131):

2.8+-0.2.

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Efficiency vs. Rates (Double Photon)

• Final Rate is about :

0.29+-0.07, for relaxed single photon path.

• HLT study group resut (CMSSW131):

0.6+-0.4.

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Efficiency vs. Rates (Relaxed Double Photon)

• Final Rate is about :

1.81+-0.15, for relaxed single photon path.

• HLT study group resut (CMSSW131):

1.8+-0.5.

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Log(eff)/log(b) vs. Cuts (Single Photon)

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Log(eff)/log(b) vs. Cuts (Relaxed Single Photon)

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Log(eff)/log(b) vs. Cuts (Double Photon)

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Log(eff)/log(b) vs. Cuts (Relaxed Double Photon)

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Preliminary Conclusion

• Rates are comparable with previous CMSSW_131 results given by HLT study group. The rates here have small errors.

• From the figures, we suggest to relax the isolation cuts, especially Ecal isolation and Track isolation. We will give the suggested thresholds later.

• Wenu and Zee samples will be included in rates calculation soon. Some other samples will be processed with more events.

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Efficiency vs. Cuts (Single Photon)

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Efficiency vs. Cuts (Relaxed Single Photon)

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Efficiency vs. Cuts (Double Photon)

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Efficiency vs. Cuts (Relaxed Double Photon)

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Rates vs. Cuts (Single Photon)

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Rates vs. Cuts (Relaxed Single Photon)

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Rates vs. Cuts (Double Photon)

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Rates vs. Cuts (Relaxed Double Photon)