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May 2, 2006 FTK Meeting 2
Physics Case Overview
LVL1
LVL2
No FTK(TDR)
FTK
1j2903j1304j90
ThreshTo ??
0.6 kHz ~5 kHz
1j2903j1304j90
Thresh+ b-tags+ ID
280 Hz280 Hz
100 kHztotal
2000 Hztotal
More modernbaseline hastracking atLVL2.
Time budgetis 10 ms/evtat LVL2.Even regionaltracking mayexceed this…
May 2, 2006 FTK Meeting 3
Physics CaseStatement #1
FTK vs TDR menus,i.e. no tracking atLVL2—ignore timing.
Statement #2
FTK vs nominal LVL2,incl. tracking. Need:
• FTK allows b-jet ()ID w/ b, c, q, .
• Correlation w/ offline?• Depends on environment
• LVL1 trigger rate, drivenby multijet evts, estimatedusing modern generator +parametrization of fullATLAS LVL1 simulation.
Fix LVL2 outputrate.
Limit LVL1 outputrate to sth reasonable.
Optimize LVL1 cuts& LVL2 tagging reqs, maximizing signal acceptance/significance.
Same as stmt #1,but add triggertiming into the eqs.
Hard to estimate,large uncertainties.
But more realistic,stronger case.
May 2, 2006 FTK Meeting 4
Estimating LVL1 rates• LVL1 rate ≈ LVL1 QCD rate.
• Jets 3 & 4 important for our processes Use generator w/ ME description of these jets; also
need appropriate ME/PS matching: Sherpa.
• Rates may be dominated by tails of LVL1 response. Use fast simulation of multijets, parametrize
response of LVL1 using fully simulated dijet events.
May 2, 2006 FTK Meeting 5
Sherpa+ATLFAST status• 10M evts produced using 22 + 23 ME processes, with
ycut = [20, 25] GeV.
– Also 10M with just 22 ME, ycut = 25 GeV for comparison.
– 22 + 23 + 24 ME is ready for production, but tier2 condor problems causing delay.
• Known problems/questions (waiting to hear from authors):– ME does not include b quarks. Should be easy to add.
– UE/MPI turned off by default. Does Sherpa include a model reasonable for LHC?
– Error messages on ~2% of events. Relevant?
May 2, 2006 FTK Meeting 6
LVL1 Jet Trigger Response• Updated parametrization for jet response available, using
11.0.42.• http://hep.uchicago.edu/~brubaker/misc/useFitFunction.C
The total pass rate is dominated by a small fraction of the Sherpa events. So statistics can still be a problem. 10M looks OK, here for a 4j40 LVL1 trigger.
• Now using uncalibrated, unsmeared ATLFAST jets as starting point.– Calibration made biggest difference.
• New CSC dijet samples are finishing up on CAFs around the world.– Big problems getting at data in ATLAS…
May 2, 2006 FTK Meeting 8
LVL1 Tau Trigger Response• Tau-trigger response fit in progress.
– Could LVL1 trig rate get sizeable contribution from real taus? If so, need parametrization.
ATLFASTjet pT (GeV)
cluster ET response
LVL1
t E
T (
GeV
)
ATLFASTjet pT (GeV)
May 2, 2006 FTK Meeting 9
Trigger Timing Issues• http://hepunx.rl.ac.uk/atlasuk/simulation/
level2/meetings/PESAlvl2IDswReview2005/TIMENOTE/l2time_note.pdf : LVL2 tracking timing note, summer 2005.
May 2, 2006 FTK Meeting 10
Timing prospects• Table on previous page is time per RoI, using
0.2x0.2 size.– They show potential factor of 2 improvements.– Adjust for larger RoI size to do b-tagging: x5.– Adjust for # of RoI per typical event: x4.
• So that makes 120 ± 100 ms per event—budget is 10 ms!
• John Baines guesses another factor of 2 possible.• $1MQ: What is the irreducible time per event,
even if FTK provides tracks? Must be < 10 ms…
May 2, 2006 FTK Meeting 11
Next steps• Physics case note started.
• Apply everything to Hhh4b channel.
• Improvements to sherpa samples and parametrizations if not too disruptive or time-consuming.
• Incoming UC grad student can work on VBF Hbb.