July 20, 2005S.Abdullin SUSY Triggers1 Salavat Abdullin For CMS Collaboration SUSY 2005, July 18-23,...

July 20, 2005 S.Abdullin SUSY Triggers 1

Salavat Abdullin

For CMS Collaboration

SUSY 2005, July 18-23, 2005Durham, UK


Outline

LHC rate challenge

mSUGRA test points

L1 trigger

L2 inclusive jet + ETmiss

L2 trigger cuts optimization

More (cross-) triggers

QCD multi-jet rate

Summary


Triggering on SUSY : Rate Challenge

Task : reduce 40 MHz bx rate ( ~1 GHz pp) O(100 Hz)

To preserve maximal SUSY signal efficiency in jets + ET channel

Recon. MET (hi lumi)Recon. MET (low lumi)Gen. MET (hi lumi)Gen MET (low lumi)

Recon. MET (hi lumi)Recon. MET (low lumi)Gen. MET (hi lumi)Gen MET (low lumi)

Expected Missing ET Rate Expected Missing ET Rate

Calo resolutionCalo resolution

Requiring a rate to tape of a ~few Hz implies an inclusive single-jet threshold of 350-500 GeV and an inclusive missing ET threshold of 100-170 GeV

Low lumi Low lumi

High lumi High lumi

Inclusive Jet Rate (cone algorithm, R=0.5)Inclusive Jet Rate (cone algorithm, R=0.5)

Full GEANT-basedCMS simulation +OO reconstruction

CMS DAQ TDRCERN/LHCC 2002-26


SUSY Points

DAQ TDR points

http://cmsdoc.cern.ch/cms/PRS/susybsm/msugra_testpts/msugra_testpts.html

mSUGRA low-mass test points (“4-6”) have beenchosen fo DAQ TDR: -close to the Tevatron reach-different final state topologies(backup slides contain more details)

mSUGRA high-mass points(“7-9”) from DAQ TDR arenot considered hereas having fairly high trigger efficiency

DAQ TDR points

“LM” and “HM” points (low andhigh mass) for Phys. TDR


L1 SUSY Triggers

L1 Jet&MET triggers alone are > 80 % efficient,

All L1 triggers ~ 89-96% CMS Note 2003/028

SUSY signal efficiency (%) and background rate (kHz)

Differ from DAQ TDR numbers

as not 95% cuts 96.2%

96.3%

88.9%


Inclusive SUSY Jet+MET

1

2

-1

QCD L2 rate (Hz)

mSUGRA 5 L2 Efficiency

Running a bit ahead –chosen L2 cuts yield ~ 45-65 % efficiencyat a few Hz of QCD rate

Jet1 threshold (150 GeV) -calibratedMET threshold (92 GeV) -raw


Chosen L2 Triggers (I)

L2 triggers : a combination of J1+MET and J4J1+MET works for “standard” SUSY, while J4 - for most challenging (fot trigger) R-parity violation scenario 3j, points 4R, 5R, 6R

J4 MET, J1 fixed @ 150 GeV


Chosen L2 Triggers (II)

Cuts were optimized simultaneously for all 6 probing SUSY points using Genetic Algorithm for given rate allocation of ~ 12 Hz (more details can be found on the backup slides)

SUSY signal efficiency (%) and background rate (Hz)

mostly QCD

113 GeV at 95% effIn DAQ TDR

180 & 123 GeV at 95% eff in DAQ TDR


More Triggers For SUSY

Lepton + MET - SM bkgd. : normalize predictions for W and tt

- might add smth. to SUSY signal, especially if decay leptonically

-

MET+lepton+jet might be too complicated, so - lepton + MET (above) - jet + MET (exists) - lepton + jet (1/2 exists, for electrons)

2 leptons + MET might help to keep low thresholds and low rates

The efficiencies of these triggers (above) for SUSY have to be studied for CMS Physics TDR


L1-L2 Streams For SUSY

Among various possible combinations of L1 and L2 triggersthere are typically just a few “leading” streams which providethe essential part of the signal efficiency

For instance, among 18 L1-L2 streamsconsidered, only 6 are essential both for R-parity conservationand violation scenarios.


QCD Multijet Rate Issue

QCD multi-jet is a main rate component, about 90% of the total rate even at L2, so since years there was a question about possible significant underestimate of the QCD rate

All previous rate calculations have been made with PYTHIA (shower model)

Now a preliminary comparison of the inclusive jet ET

distributions is made at the level of the MC jets betweenALPGEN 2.01 and PYTHIA 6.2 (“old” shower model)

Details of calculation can be found on the backup slides


Inclusive Jet ET Distributions

For low-Et and “medium”-Et 3d and 4th jets the difference does not look significant

Harder jet ET cuts to be investigated !


Summary

No problem with L1 trigger even for low-mass SUSY

L2 has to be optimized due to the limitedbandwidth allocated to jets and MET

More cross-triggers might possiblyincrease L2 SUSY signal efficiency(to be studied)

Preliminary comparison of 3d and 4th jets inclusive distributions show a goodAgreement between ALPGEN and PYTHIA


Backup SlidesBackup Slides


DAQ TDR mSUGRA Test Points

Tevatron mass reach


R-Parity Violation Scenario


Probing Points with R-Parity


L2 MET Distributions

Similar to t tSimilar to t t_


Number of L2 Jets


Leading L2 Jets


Hybrid Genetic Algorithm (I)


Hybrid Genetic Algorithm (II)


Hybrid Genetic Algorithm (III)


QCD Simulation with PYTHIA

PT > 20 and 120 GeV

Official CMS Production data cards

^

To put ALPGEN and PYTHIA data on the common ground

a cut of 120 GeV is applied on the 1st jet ET in both samples


ALPGEN samples

ALPGEN v201 Q2= PT

2(parton) PDFs CTEQ5L

Matching scheme CKKW (M Mangano impementation in Alpgen, see http://mlm.home.cern.ch/mlm/alpgen)

Jet parameters for matching: E

T(jet) > 15 GeV

R(jet) = 0.525, R(parton-jet) < 0.7875


ALPGEN samples

2-to-2 : Npartons

=2; PT(parton)>20 (100) GeV; |eta|<5

R(parton-parton) >0.7

2-to-3 : Npartons

=3; PT(parton)>20 (100) GeV; |eta|<5


2-to-4 : Npartons

=4; PT(parton)>20 (100) GeV; |eta|<5


(parton= outgoing parton)


samples cross sections

sample (matched-alp) (unw-alp) matching (pythia) 2-2 0.4 mb 0.8 mb 0.5 - 2-3 0.02 mb 0.06 mb 0.3 - 2-4 0.0024 mb 0.016 mb 0.15 - total 0.45 mb 0.876 mb - 0.83 mb

sample (matched-alp) (unw-alp) matching (pythia) 2-2 6 × 10-4 mb 0.0013 mb 0.45 - 2-3 1.5 × 10-5 mb 4 × 10-5 mb 0.38 - 2-4 1 × 10-6 mb 3.6 × 10-6 mb 0.27 - total 6.16 ×10-4 mb 1. 344 × 10-3 mb - 6.3×10-4 mb

20 GeV

100 GeV


Pseudorapidity distributions

3d jet ET > 100 GeV,4th jet ET > 100 GeV

July 20, 2005S.Abdullin SUSY Triggers1 Salavat Abdullin For CMS Collaboration SUSY 2005, July 18-23,...

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Transcript of July 20, 2005S.Abdullin SUSY Triggers1 Salavat Abdullin For CMS Collaboration SUSY 2005, July 18-23,...