Overview of Tau Trigger Performance

Transcription

1 Overview of Tau Trigger Performance ATLAS Trigger/Physics Week March 20, CERN Eric Torrence University of Oregon on behalf of the Tau Trigger group

2 Introduction Largely based on talk at Krakow workshop New TTP03 ntuples Release 2.0.6, L2 tracking bug fixed New information about e/mu ROIs More/larger signal samples Updated tables (no significant changes) Start looking at 2 lepton triggers Eric Torrence 2

3 Samples TauTrigPerformNtuple Sample Run Events xsec (pb) J k.74E J 50 30k.38E9 J k* 9.33E7 J k 5.88E6 W k Z k H k SU 540 k SU k Disclaimer - snapshot of 2.0.6, lots of code development, not so much performance tuning (yet) No min-bias available (scale rates by ~2?) Eric Torrence 3

4 Analysis tools Package TrigTauPerformAnalysis Apply fiducial cuts to MC truth taus Chain together {L, L2, EF} objects - sequential selections Selectors for menus (tau5i) or arbitrary cuts Tools for association of truth - trigger chain - offline Analysis macros to produce standard plots/tables of trigger rates and event (or ROI) efficiencies Aim to have consistent and reproducible results (code in CVS) for CSC notes Most important, can run all this on my laptop Eric Torrence 4

5 Standard Fiducial Cuts ηvis < 2.5 Efficiency Daughter of gauge boson (W, Z, H,...) Semi-leptonic tau decay Optional Fiducial Cuts Pt(vis) > 25 (e.g.: tau25i) Specific decay mode (pr, 3pr, pi, rho) dr match with offline reco object (taurec p3p) Start with true taus (denominator), match nearest trigger object (numerator) within dr cut (0.2 for L, 0. for offline) Eric Torrence 5

6 Efficiency L L2 EF W τ ν tau25i Efficiency True Visible Pt (GeV) True Visible Pt Efficiency True Visible Eta True Visible Eta Eric Torrence 6

7 Stepwise Efficiency Sequential Efficiency L L2 EF tau25i W τ ν True Visible Pt (GeV) Turn-on dominated by L (energy resolution) L2/EF currently efficiency approximately constant ~80% Eric Torrence 7

8 L Turn-on L Efficiency taui tau5i tau20i tau25i tau35i W τ ν True Visible Pt (GeV) L Energy resolution broad and biased for taus Plateau not reached until ~ GeV above nominal cut Non-zero efficiency below nominal cut also... Eric Torrence 8

9 prong vs. 3prong taui tau5i tau20i tau25i tau35i prong only True Visible Pt (GeV) taui tau5i tau20i tau25i tau35i W τ ν prong only True Visible Pt (GeV) Eric Torrence 9

10 Efficiency Tables Selector L (%) L2Cal (%) L2Trk (%) EF (%) No Offline Matching tau5i (p vis t > 5) tau25i (p vis t > 25) tau35i (p vis t > 35) Offline Reco Matched tau5i (p vis t > 5) tau25i (p vis t > 25) tau35i (p vis t > 35) W τ ν Incremental and cumulative efficiency shown Efficiency for reco-matched taus better (30-50% relative) Eric Torrence

11 tau5i background rates L Rate L2 Rate EF Rate L Rej. L2 Rej. EF Rej. J J J J Sum 2083 Hz 774 Hz 74 Hz Table : tau5i background rates, L = 3 cm 2 s default cuts (not particularly well tuned) L rate almost tolerable HLT rates too high by 5-x (Minbias will be worse!) Need to improve HLT (particularly L2) rejection Eric Torrence

12 L = 3 Rate Summary Selection L Rate L2 Rate EF Rate W τν Z ττ (Hz) (Hz) (Hz) (p vis t > 2) (p vis t > 2) tau % 45.5% taui % 36.0% tau % 35.3% tau5i % 29.2% tau20i % 25.4% tau25i % 20.% tau35i %.5% Table 2: J0-J3 event rates at L = 3 cm 2 s Snapshot of menus Factor of 200 larger at L = 2 x 33 Eric Torrence 2

13 L MET Selected Event Rate (Hz) tau25i + L MET L L2 EF J0-J3 L= L MET Cut (GeV) Events passing L/L2/EF with additional cut on L MET tau25i shown as baseline Need significant cut (~MET30) to get x rejection Eric Torrence 3

14 L MET Rates Selection L Rate L2 Rate EF Rate W τ ν (Hz) (Hz) (Hz) (p vis t > 2) tau5i % + MET % + MET % + MET % tau25i % + MET % + MET % + MET % tau35i % + MET % + MET % + MET % Not updated! Table 3: J0-J3 event rates at L = 3 cm 2 s Eric Torrence 4

15 L eff vs. MET MET00 MET MET20 MET30 MET40 W τ ν True Visible Pt (GeV) Correlation between L Et and MET Cutting on L MET rejects low Et taus Plateau efficiency shifted to higher visible Pt Probably not the best way to understand trigger Eric Torrence 5

16 Mixed triggers Most tau pair decays involve leptons (e, µ) ee, µµ, eµ: ~3% eh, µh: ~46% hh: ~4% Can we do (much) better using mixed triggers? Can we get low Et samples for trigger understanding? HLT performance boosted by (Rejection) 2 Rates typically limited by L performance First look at this information in TTP03 Eric Torrence 6

17 2 Tau L L Et J0-J3 L= L Et Rate (Hz)/bin Integral L Rate (Hz) taui+tau25i Plots show L Et cut, not nominal threshold taui cuts used as baseline Exact rates need proper menu selection 2 tau5i Quite acceptable rates at low thresholds ~200 Hz Eric Torrence 7

18 2 Tau results L Selection L Rate L2 Rate EF Rate Z ττ H ττ SU SU3 (Hz) (Hz) (Hz) (588) (8332) (540) (5403) 2taui % 26.8% 3.9% 6.9% 2tau5i % 2.3% 3.2% 5.2% 2tau20i % 9.5% 2.8% 4.6% taui+tau5i % 28.2% 4.% 7.0% taui+tau20i % 28.4% 4.2% 7.% taui+tau25i % 27.0% 4.0% 6.6% Table 5: J0-J3 event rates at L = 3 cm 2 s 2 tau5i similar in rate to taui+tau25i Signal efficiency improved for asymmetric thresholds Signal event efficiencies shown with no fiducial cuts Far better Z efficiency than pre-scaled taui Eric Torrence 8

19 Tau + lepton triggers Entries 599 Mean dr 2 from E to tau5i W τ ν (hadronic) RMS Started with E (mistake!) Not exclusive e - L Large overlap w/ tau ROIs Muons very orthogonal L E - Tau Radius^2 In W τ ν (57) L:.97 E per tau5i L2: 0.66 E per tau5i EF: 0.6 E per tau5i Use arbitrary cut of dr>0.2 to make sensible study No idea how to handle this in real trigger... Eric Torrence 9

20 L Tau Et Tau - Electron example J0-J3 40 L= 3 35 L 30 Integral Rate (Hz) L Elec Et 2 khz L rate around taui + E (e5i much better) - Not all menus in dr 2 Tau-E Eric Torrence 20

21 Tau - lept rates Selection L Rate L2 Rate EF Rate Z ττ H ττ SU SU3 (Hz) (Hz) (Hz) (588) (8332) (540) (5403) taui+e % 55.7% 2.8% 27.3% tau5i+e % 52.3% 9.7% 24.7% taui+e5i % 0.7% 3.5% 4.4% tau5i+e5i % 0.6% 3.% 4.0% taui+mu % 0.3% 2.6% 2.4% tau5i+mu % 0.3% 2.2% 2.2% taui+mu % 0.% 2.4% 2.0% tau5i+mu % 0.%.9%.9% Table 6: J0-J3 event rates at L = 3 cm 2 s E rates very high (our fault?) Low background rates achievable (but also low efficiency) Much more to look at here Beware of Monte Carlo filter (e.g. 8332)! Eric Torrence 2

22 Summary Ready to start making detailed performance studies HLT needs to be optimized (tightened) Much work has gone into preparing code (2 series) 2 tau triggers look interesting for getting low Et samples, especially with asymmetric thresholds First look at tau + lept triggers, much more to be done here Eric Torrence 22