1. Progress on jet trigger response functions FTK Physics Case Meeting 06/16/05 Erik Brubaker University of Chicago

2. June 16, 2005FTK Physics Case Meeting2 Reminder: Purpose Making the physics case for FTK means studying signal and background trigger rates for several processes. ATLAS full simulation is very slow. Solution: use fully simulated events to parameterize the L1 jet trigger response vs ATLFAST jet p T. Then all the various processes for physics studies can be studied using ATLFAST.

3. June 16, 2005FTK Physics Case Meeting3 Some definitions Dijet samples: –J1: 17 < p T < 35. –J2: 35 < p T < 70. –J3: 70 < p T < 140. –J4: 140 < p T < 280. –J5: 280 < p T < 560. –J6: 560 < p T < 1120. –J7: 1120 < p T < 2240. –J8: 2240 < p T. Cone jets –R=0.4 –Seed > 2 GeV ATLFAST jets –Cone 0.4 –Seed > 1.5 GeV? L1 jets –8 x 8 trigger towers –|  | < 2.6 L1 taus –1 x 2 towers (EM), 2 x 2 towers (HAD) –Isolation EM < 2 GeV, HAD < 2 GeV.

4. June 16, 2005FTK Physics Case Meeting4 Response plot: change 4x4 to 8x8 Better resolution

5. June 16, 2005FTK Physics Case Meeting5 Zoom out Saturation effects: any saturated trigger element  pinned cluster energy. Some code missing… Second band of response not understood. Under investigation.

6. June 16, 2005FTK Physics Case Meeting6 Parameterize the response L1 E T for slices of ATLFAST p T 17 3337 2521 29 41 77 45 6961 53 85 93101 109

7. June 16, 2005FTK Physics Case Meeting7 Functional Form Use Landau function for low-p T jets, Gaussian for high-p T jets. Quadratic dependence of Gaussian mean, width on jet p T. Fixed parameters for Landau, slowly varying with jet p T. See function sent via email: http://hep.uchicago.edu/~brubaker/misc/useFitFunction.C More technical details available upon request. http://hep.uchicago.edu/~brubaker/misc/useFitFunction.C

8. June 16, 2005FTK Physics Case Meeting8 Quality of Fit Not quantitative yet. A few trouble spots. Concentrate on regions of most importance— feedback!

9. June 16, 2005FTK Physics Case Meeting9 How to use it—not so simple! For a 2-jet trigger, with thresholds c 1 and c 2. Then what? How to get probability for event to pass a set of triggers? –I’ll think about this and try to supply a prescription. float probJetPasses[MAXATLJET][2]; for (int i = 0 ; i < nAtlJet ; i++) { probJetPasses[i][0] = TrigProb(ptAtlJet[i],c1); probJetPasses[i][1] = TrigProb(ptAtlJet[i],c2); }

10. June 16, 2005FTK Physics Case Meeting10 Tau trigger response Parallel question: how do ATLFAST jets fire tau triggers. Tau trigger has isolation cuts: –EM 12-tower ring. –Had 12-tower ring. Need to rerun trigger simulation with looser energy and iso requirements to form an RoI. Parameterize energy response, isolation separately? Correlated? Need input from those working on taus.

11. June 16, 2005FTK Physics Case Meeting11 Plan before next time Parameterize tau trigger energy response to jets, and efficiency of isolation requirements. Improve jet trigger energy parameterization as necessary. Understand how to go from P(jet triggers | ATLpt, L1threshold) to P(event triggers | [list of jets],[list of thresholds]). Start work on H  hh  bbbb process study.