1. Eric TorrenceJanuary 2009 1 Oregon Tau Activities Tau Trigger Efficiency Z→ττ Dijet Fakes Tau Spin Analysis Tau Trigger Activities Validation HLT Monitoring TTP Ntuples

2. Eric TorrenceApril 2009 2 Efficiency Motivation Why measure trigger efficiency at all? Physics Typically need product ε(trig) x ε(reco) Sometimes need ε(reco) alone Never (?) need ε(trig) alone Can factorize and measure ε(trig) / ε(reco) Trigger Understanding Trigger must be understood/commissioned before first “real” taus are seen Both need ε(trig) dependence on key variables

3. Eric TorrenceMay 2008 3 Analysis Overview Z→ττ→lh (Oregon, Uppsala) Motivated by analysis in offline Tau note (and before) Try to optimize for trigger efficiency measurement Check results - get experience with analysis Fake offline taus in jet events (Oregon, UIUC) Motivated by D0 analysis High statistics monitoring analysis Possible to make real efficiency measurement?

4. Eric TorrenceMay 2008 4 Z→ττ Overview Start with lepton trigger: electron or muon Offline object selection: electron loose/medium/tight, Staco muon, tau 1p3p (cut-based for now) in |eta|<2.5 Remove overlaps (mu, electron, tau priority) Should use offline tools here... Reconstruct Z momentum using MET technique Cut on Z mass to improve purity Additional cuts also explored (motivated by note) includes MET, tau-lept angle Verify results in offline note, explore background estimation Look at improvements or biases for trigger efficiency

5. Eric TorrenceMay 2008 5 Typical Results Select 240 signal 60 < mRec < 120 in 100 pb -1 Entirely based on private code from ntuples Will integrate trigger efficiency effort into broader SM benchmark Z→ττ→lh analysis framework Reco Mass (GeV) MC Events Signal Tight Electron (Pt > 15) tau1p3p (Pt > 10) MET > 20, m(tau-l), angles

6. Eric TorrenceMay 2008 6 Current Work Looking at bias in extracted efficiency due to e.g.: MET cut Considering simpler “visible mass” observable - less dependence on MET, better resolution, possibly no worse that what we are using now. True Efficiency vs. Et for different MET cuts No additional bias apparent!

7. Eric TorrenceMay 2008 7 Efficiency from fakes Lots of di-jet events pass offline tau selection (minbias fake rate ~ 0.1%) If they look this much like taus, they had better fire the tau trigger Probably not a high-accuracy measurement, but should provide lots of statistics Expect 430 tau events/12 hours with nominal 10 Hz minbias trigger, possibly more with pre-scaled jet triggers.

8. Eric TorrenceApril 2009 8 Fake 3pr taus 10 TeV W→τν vs. J0-J4 unweighted tauRec L>5 Good to ~5-10% L1L2 EF Reco Et

9. Eric TorrenceApril 2009 9 Fake 1pr taus 10 TeV W→τν vs. J0-J4 unweighted tauRec L>5 Good to ~10-20% Reco Et

10. Eric TorrenceJanuary 2009 10 Other Activities Tau Polarization (Robinson/Frey) Use tau decay properties to spin-analyze tau production Current work done for Z’ by NBI-Copenhagen Likely long-term project (not for first data) Tau Trigger Validation (Robinson/Reinsch/Strom) Oregon responsible for HLT software validation Lots of (not very glamorous) work Tau Trigger Monitoring/Commissioning (Shamim/Torrence) Tau Trigger group ntuples and analysis code Responsibility for tau trigger monitoring