Skeleton outline for the physics case document

1. Skeleton outline for the physics case document M. Shochet December 15, 2005

2. Physics Case for the FTK Fast Track Finder • Introduction • The general argument: unknown new physics  best toolbox • Importance of the 3rd generation to new physics: EWK symmetry breaking, SUSY, … • Challenge of efficiency, rapid identification of b and  jets in the trigger because of large backgrounds • Early access to high quality tracks can give rapid rejection in L2  lower deadtime  can reduce the L1 threshold to increase physics efficiency • Rapid tracking can be useful for many purposes including calibration: ex, single isolated track trigger for calorimeter calibration (low PT & W→) • Here we focus on 3rd generation partons • Remaining sections:

3. b-jet ID • -jet ID (1 & 3 prong) • Z→bb • bbH/A→ 4 b’s (& 2 b’s 2 ’s ?) • VBF production of H→ • H→hh→4b’s • Bs→ • (generic l triggers ?) • Summary & conclusions * As we go, we have to keep tabs on the total requested additional L1 jet trigger rate (use common thresholds when possible).

4. The CDF Experience ex: early predicted trigger rates vs. reality; SVT success – B physics expectation before run I vs. what was done (SVT needed for unanticipated physics); Zbb – bb purity after trigger • Overview of FTK (technical details elsewhere) • Rapid selection of b-jets • Simulation samples used • Optimization procedure • b-jet efficiency vs light quark & gluon rejection factor • Comparison with planned trigger and offline algorithms • Rapid selection of  jets Same bullets as in III with addition of • Triggering on 3-prong  decay (for polarization information) • Z→bb • Measure b-jet response of ATLAS calorimeter, check the shift when b semileptonic decay is identified, additional check of overall ATLAS jet energy scale • Problem: maintaining low enough L1 rate and having low MJJ turn-on to get background shape

5. Solution: high PTZ’s (3-jet trigger) • Background & signal after trigger • Z mass uncertainty & width vs. integrated luminosity • bbH/A→4 b’s • pick a few points in parameter space (just) outside ATLAS sensitivity region • Signal & background samples used (describe use of ATLFast and use of transfer functions) • Background rate & signal efficiency vs selection criteria • Observation significance vs integrated luminosity & comparison to ATLAS baseline result • VBF production of H Same as above, with discussion of forward jets &/or rapidity gaps . . .