DILEPTON TRIGGERS FOR SUSY

1
DILEPTON TRIGGERS FOR SUSY

• Melisa Rossi
• Università degli Studi di Udine
• CDF ITALIA Bologna
• December 13-14 2004

2
OUTLINE

• Situation before shutdown '04
• SUSY TRIGGER before shutdown
• Our major concerns
• SUSY TRIGGER studies up to shutdown '04
• SUSY TRIGGER monitoring
• Conclusions

3
Situation before shutdown 04

• General trigger concerns
• Growth terms in trigger x-sections
• Deadtime from event builder and CSL _at_ high
  luminosity
• L2 processing deadtime _at_ all luminosities
• TDWG actions
• Raised prescales and tightened cuts on many
  physics triggers (June-August 2004)
• Reduced deadtime significantly, but not enough to
  go beyond 1E32
• TDWG explicitly asked for input from Physics
  Groups
• CDF should be ready for Lpeak 1.5E32cm-2s-1 in
  2005 fall

4
SUSY TRIGGERS before shutdown

• Strategy
• achieve maximum acceptance
• SUSY yields leptons typically produced with low
  pT
• keep calibration and monitoring samples in the
  same datset
• extraction of unbiassed lepton samples from same
  datset
• detector conditions naturally folded in
• define standard lepton objects
• definitions do not depend on specific trigger
  path
• Multilepton dilepton trigger
• All paths contribute to acceptance

CORE PATHS COMPLEMENTARY PATHS COMPLEMENTARY PATHS
L1L2 2 Low-pt leptons Medium-pt leptontrack High-pt inclusive lepton
L3 2 Low-pt leptons 2 Low-pt leptons 2 Low-pt leptons
(CDF6074)
5
Our major concerns

• Large inclusive L2 cross section
• In particular for complementary paths
• TDWG interim countermeasure (June 2004)
• L2_CEM12_PT8 changed to L2_CEM8_PT8_CES3_DPS
• x-section stability
• Possible growth factor effect _at_ high luminosity
• Understanding overlaps

• High-pt inclusive muon L2_CMUP6_PT8
• High-pt inclusive electron L2_CEM12_PT8
• Medium-pt electrontrack L2_CEM8_PT8_CES3__TRK8

6
L2 X-SECTIONS vs. time
On average
L2 complementary path sTOT(nb) sEX(nb)
L2_CMUP6_PT8 180 100 (55)
L2_CEM8_PT8_CES3__TRK8 110 10 (9)
L2_CEM12_PT8 270 60 (22)
(sEX effective L2 x-section)
e.g. L2_CEM12_PT8
sEX
sTOT
L3 Monitor dataset 50pb (MONITOR_L3TAG_PS200)
7
L2 X-SECTIONS (nb) vs. L (cm-2s-1)
L3 Monitor dataset 40pb (MONITOR_L3TAG_PS200)
8
L2 X-SECTIONS (nb) vs. L (cm-2s-1)

• Inclusive electron
• No growth factor in stot
• Growth in sEXdue to dynamically
• prescaled competing triggers
• sEX 100nb

L3 Monitor dataset 6pb (MONITOR_L3TAG_PS200)
9
L2 OVERLAPS

• Inclusive electron L2_CEM12_PT8
• expected effective x-section 100nb
• 50 overlap with L2_CEM16_PT8 (conservative)
• expected effective CEM16 x-section lt 50 nb
• keeping CEM16 instead of CEM12 produces a 4
  acceptance reduction
• Electrontrack L2_CEM8_PT8_CES3__TRK8
• expected effective x-section 40nb
• 75 overlap with L2_CEM8_PT8_CES3__TRK5_DPHI10
• will be modified with new trigger table
• 60 overlap with L2_CEM12_PT8
• 35 overlap with L2_CEM16_PT8

LARGE OVERLAPS ALMOST NOT CHANGING WITH LUMINOSITY
10
SUSY TRIGGER Monitoring

• Definition of standard lepton objects
• Instead of 20 trigger paths, 6 lepton objects
• CEM4,CEM8,PEM8,CMU4,CMUP4,CMX4
• Example
• CEM4 L1_CEM4_PT4 L2_CEM4_PT4_CES2
• Simplification of trigger calibration
• Compute efficiency for each lepton object
• Good run list per lepton object
• Need of a suitable monitoring variable

11
SUSY TRIGGER Monitoring

• Monitoring Variable R
• Trigger path lepton1 lepton2 _at_ trigger level
• For each trigger path count
• N1 triggered events with offline lepton1
• N2 triggered events with offline lepton2
• D triggered events
• sort of purity
• expected to be stable in time
• expect no significant differences for given
  lepton type between different trigger paths

R1 N1/D for events satisfying standard
lepton1 definition R2 N2/D for events
satisfying standard lepton2 definition
12
SUSY TRIGGER Monitoring

• DATA CONSIDERED
• DQM CRITERIA
• (according to Good Run list v7)
• ONLINE bits required to be good
• CLC,L1T,L2T,L3T,CAL,COT
• OFFLINE bits required to be good
• COT,CAL
• From 2002 to shutdown 2004

1700 runs 380pb-1
13
SUSY TRIGGER Monitoring
R distribution vs. Run
14
SUSY TRIGGER Monitoring

• Supect run definition in 2 steps
• Test for R indipendence of trigger path for each
  lepton object
• Rlepton average value for each run and for each
  lepton object
• R value for the single trigger path
• The run is suspect if R-Rlepton gt 10s
• Test for Rlepton stability in time
• ltRleptongt Rlepton local average over 20 runs
• If Rlepton-ltRleptongt gt 5s, the run is suspect

15
SUSY TRIGGER Monitoring

• Suspect run luminosity
• for lepton object

Rlepton stability
CEM4
CEM4 0pb
CEM8 5pb
PEM8 7pb
CMX4 30pb
CMU4 5pb
CMUP4 1pb
Step in distribution correlated to change in
trigger table Em from electron track, not from
cluster
total suspect luminosity 37pb out of 380 pb
16
CONCLUSIONS -1-

• SUSY trigger up to shutdown 04
• Complementary paths are healthy
• No appreciable growth factors
• No solid reason for removing L2_CEM12_PT8
• prescaled triggers useless for potentially small
  signals
• possible substitute is L2_CEM16_PT8
• CDF should be ready for 1.5E32cm-2s-1
• the whole CDF trigger will be revised
• need to re-think also the SUSY trigger for 2005
  fall

17
CONCLUSIONS -2-

• Monitoring
• Variable choice R
• gives information about event quality (purity)
• behaves as expected
• locally stable in time
• steps correlated to trigger table changes
• Good run list done
• 37pb of suspect luminosity
• the largest fraction comes from CMX (30pb)