Efficiency of the Efficiency of the L1 Trigger for SUSYL1 Trigger for SUSY

Study performed byStudy performed by

L. Boldizsár, P. HidasL. Boldizsár, P. HidasKFKI BudapestKFKI Budapest

J. Erö, M. Fierro, A. Jeitler, N. Neumeister, P. Porth, J. Erö, M. Fierro, A. Jeitler, N. Neumeister, P. Porth, H. Rohringer, L. Rurua, H. Sakulin, A. Taurok, C.-E. H. Rohringer, L. Rurua, H. Sakulin, A. Taurok, C.-E.

WulzWulzHEPHY ViennaHEPHY Vienna

presented by

Claudia-Elisabeth WulzClaudia-Elisabeth WulzCPT Week, CERN, 8 May 2003

C.-E. Wulz 2 CPT Week, May 2003

Tridas Scenario and Physics Channels

• Luminosity: 2x1033 cm-2s-1

• Tridas scenario: 50 kHz Level-1 trigger rate (16 kHz with safety factor)• 8 physics channels studied (A-H)

- A: Smuons at Snowmass point 1a - LL with L ->

- B: Charginos/neutralinos at Snowmass point 1a -

- with ->

and ->

; ->

; -> e

- C: Gluinos/squarks Snowmass point 1a

- D: Gluinos/squarks Snowmass point 2

- E: Sparticles JetMet mSUGRA4

- F: Sparticles JetMet mSUGRA5

- G: Sparticles JetMet mSUGRA6

- H: WW with W -> (benchmark channel)

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Parameter Choice

Snowmass point 1a

Snowmass point 2

tan = 10, sgn() = A0 = 100 GeV (A,B,C)

A0 = GeV (E,F,G)

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mSUGRA Jet and Missing ET distributions

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Monte Carlo Input

A, B, C, D, H: PYTHIA 6.158 E, F, G: ISAJET 7.51

Parton distribution functions CTEQ5L used for all channels.1000 events for SUSY channels, 2000 events for WW channel.

On average 3.5 minimum bias events produced with PYTHIA 6.158 added.

C.-E. Wulz 6 CPT Week, May 2003

Detector and Trigger Simulation

CMSIM 125 used for hit simulation, separately for signal and pile-up.Digis produced with ORCA 6, mixing signal plus in-time pile-up.Out-of-time pile-up simulated by superposing bunch crossings -5, …, +3.HCAL non-linearity correction applied.Intrinsic RPC noise not added due to CPU time constraints.

Level-1 performance simulated in ORCA. Bit-wise arithmetic used wherever possible.

Results are given at the end of the Level-1 chain, i.e. at the output of the Global Trigger.

C.-E. Wulz 7 CPT Week, May 2003

Trigger Menu

Thresholds chosen to yield total rate of 16 kHz, which are allocated to physics triggers at Level-1.Muon thresholds are from the DAQ/HLT TDR.

Bandwidth quota is divided into four roughly equal groups:/e /ee/ Jets, ET sums and combinations

Total rate is smaller than sum of rates for 4 groups due to overlaps.

3.6 kHz}

4.3 kHz

3.0 kHz}

3.6 kHz}

}

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Efficiencies

Nr. of events generated (no geometrical restrictions)Efficiency = Nr. of events passing L1 trigger in its fiducial volume

Individual efficiency: eff. of a trigger as if it were the only trigger applied In practice: triggers overlap

Additional efficiency: events found by previous trigger not counted (order of trigger conditions relevant)

Exclusive efficiency: eff. for events found by one and only one trigger

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Efficiencies A-D, H (WW)

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Efficiencies E, F, G (mSUGRA) Efficiencies at the upper mass reach of Tevatron Run II

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Total Efficiencies

Channel Total efficiency A 93.4 %

B 72.3 %

C 97.9 %

D 100.0 %

E 96.2 %

F 96.3 %

G 88.9 %

H 81.3 %

Chargino/neutralino channel has lowest efficiency.

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: generated ET vs of highest-ET electron

ET is either low or electrons are outside trigger acceptance

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: generated ET and E of invisible particles

Can trigger on missing ET help?

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Invisible ET about the same for accepted and rejected events, whilst E is higher for rejected than accepted events! Rejected events tend to balance their contributions in ET . Probability for cancellation high due to many invisible particles.

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Effects of thresholds, resolution, acceptance

For a qualitative appreciation of the different effects the and trigger efficiencies were studied for smuons (A) ( = 92.5%, = 68.8%) and gluinos/squarks (C) ( = 27.8%, = 13.8%).

Generated pT of 2 highest-pT muons

Smuons Squarks/gluinos

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pT of Level-1 Muon Candidates

Level-1 pT of 2 top muons

Smuons Squarks/gluinos

Single-muon threshold

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of Generated and Level-1 Muons

Generated of 2 highest-pT muonsS

mu

ons

Sq

uark

s/gluin

os

trigger acceptanceboundary

Level-1 of 2 top muons

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Conclusions

Level-1 trigger efficiencies for 7 SUSY channels and WW studied for the initial low luminosity LHC run with scenario of 50 kHz maximum Level-1 trigger rate

Most efficiencies are good, over 90%

Lower efficiency for charginos/neutralinos comes mainly from physics