September 30, 2004FTK meeting1 Making the FTK Physics Case M. Shochet 9/30/04

September 30, 2004FTK meeting2 RODsRODs SCT  Pixels  ROBsROBs ROBsROBs FTK on L1 accept “Level 1.5” silicon hitssilicon tracks Level 2 ask for ROI’s Fits into the ATLAS Trigger Architecture

September 30, 2004FTK meeting3 Reaction to FTK US: most I have spoken with: trigger is ATLAS weak spot CERN: –TDAQ: focused on their immediate tasks, which are significant –Physics: leaders are very supportive on the generic arguments as well as specific channels Fabiola Gianotti: –Unlikely to find single channel that is accessible only with FTK –If find improvement in a number of channels, that is sufficient. Then the generic argument makes the case. Giacomo Polesello: –If can be done, that would be enough.

September 30, 2004FTK meeting4 Why? The LHC will open a large new energy frontier. We are almost certain to find new physics there. But what that new physics is we don’t know. The way for us to be prepared to study that new physics with high sensitivity is to have the most powerful toolbox we can build. The ATLAS trigger is not as powerful as it could be. –ATLAS trigger has reasonable thresholds for e’s and  ’s. –Jet trigger thresholds are very high because their raw rates are very large and there isn’t much you can do to reduce this in real time.

September 30, 2004FTK meeting5 F. Gianotti, LHCC, 01/07/2002 Triggers without FTK Scenario: L= 2 x deferral ATLAS 0.2 J200 3J90 4J65 40  20 2  MU20 2MU6 HLT rate (Hz) HLT selection LVL1 rate (kHz) LVL1 selection 25 j400 3j165 4j110 This is too large for objects in much of the mass range of interest.

September 30, 2004FTK meeting6 Why is this a serious problem? Whatever the source of EWK symmetry breaking, the role of the 3 rd generation is likely to be big. (coupling  M; special role, …)  Pay attention to b’s and  ’s. ATLAS trigger is fine for 1 st and 2 nd generations: e, , inclusive jets  thresholds are large; no e , ,  triggers hard to reduce L1 jet thresholds to get more b-jet acceptance because it takes a long time to reconstruct in an Intel processor all the tracks in jets and find secondary vertices ( ) If we could have all tracks with P T > 2 GeV/c reconstructed near the beginning of L2, …

September 30, 2004FTK meeting7 Physics topics for Study for measuring the b-jet response and resolution (  -jet & Z-jet balance have theory/exp problems) for M top, M Higgs, … Problem: L1 trigger rate  higher jet E T threshold high threshold  high M JJ turn-on Solution: high P T Z’s 3-jet trigger highest E T jet is not tagged bb opening angle not fixed near  lower M JJ threshold

September 30, 2004FTK meeting8 Higgs Physics How much lower in tan  can be reached? These jet P T ’s are too low for existing triggers. How much does FTK help?

September 30, 2004FTK meeting9  leptons Need lower threshold for all  triggers. How low can the threshold be? (Fabiola) –for the high P T response of TileCal across the detector –Existing thresholds (35/45 GeV) too high for W’s –(More general: isolated track triggers for calorimeter calibration – rapid level-2 rejection  higher level-1 rate) (Ian) Existing  trigger is for 1-prong only. Polarization information requires seeing other  decay modes.

September 30, 2004FTK meeting10 More (Ian) For electroweak production of anything that can be seen, masses will be low (  low P T jets). (Michelangelo) B physics (if initial  is very low) ex, General (Ian): redundancy in the trigger important for measuring efficiency

September 30, 2004FTK meeting11 What has to be done? What drives trigger decisions is background rejection, not signal efficiency. But background studies require LOTS of events. At 5 minutes/simulated event, …  Use fully simulated events to parametrize jet response (with fluctuations) jet trigger efficiency vs E T ( especially at level 1) Use full simulation to check FTK track simulation: hits (real & random), resolution Then can do convincing physics studies with fast simulation.