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Tau Performance using Z decays

Tau Performance using Z decays. This week. Z -> tau tau 10 K data RECO Studies Reconstruction and tagging performance Particle Flow Energy Corrected Jets performance. L1 Studies ‏ Trigger Performance Trigger studies for the GT Decision (using L1Extra objects) ‏. Reconstruction.

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Tau Performance using Z decays

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  1. Tau Performance using Z decays Mike Bachtis / UW

  2. Mike Bachtis / UW This week... • Z -> tau tau 10 K data • RECO Studies • Reconstruction and tagging performance • Particle Flow Energy Corrected Jets performance. • L1 Studies • ‏Trigger Performance • Trigger studies for the GT Decision (using L1Extra objects)‏

  3. Mike Bachtis / UW Reconstruction • Jets Reconstructed with iterativeCone5 algorithm • Particle Flow corrections on the iterativeCone5 Jets • Minimum Et= 10GeV • Match to MC tau with delta R = 0.3

  4. Mike Bachtis / UW Et of MC,RECO and Tagged jets MC RECO - Matched Tagged - Matched Tagged - Fake L1 Cut.... Neutrinos (MC)‏

  5. Resolution (ref to visible MC )‏ Not Corrected Corrected Mike Bachtis / UW

  6. Mike Bachtis / UW E(RECO)- E(MC) correlation Corrected Not Corrected

  7. Mike Bachtis / UW Delta R

  8. Efficiency Reconstruction Reconstruction & Tagging Mike Bachtis / UW

  9. Mike Bachtis / UW Reconstruction summary • In the 10K events set, for |eta|<2.5 • There are 9913 true taus • 9561 of them(74%) were reconstructed and matched(96%)‏ • From the reconstructed taus 7598 were tagged and matched(80%)‏ • The tagging AND matching efficiency is 77% • There are 3000(30%) tagged Jets that were not taus (fake tagging rate)‏

  10. Mike Bachtis / UW Level 1 Trigger • From 9K events • 2253 have two matched L1 tau objects (l1extra) so there are 4506 true L1 taus.. • There are also ~1200 events with two “Jets” • From the 2253 events with more >= two L1 matched taus 1947 (87%) have the two most energetic jets matched as taus • So the GT decision algorithm can be implemented using only the two most energetic L1 taus (small loss in efficiency but saves processing time and complexity)

  11. Mike Bachtis / UW DeltaR to the nearest MC tau Reconstruction L1 extra Taus The trigger resolution depends absolutely on the calorimeter segmentation... We match trigger with a deltaR cut of 0.5.

  12. Mike Bachtis / UW Di-Tau Trigger y • The default trigger requires a minimum Et threshold of 20 GeV for the two jets. • We can use kinematics for lowering the threshold and provide a good efficiency x The two taus must be back to back in this plane

  13. Mike Bachtis / UW Phi 1 vs Phi 2 Symmetric!!

  14. Mike Bachtis / UW How back-to-back are they? Matched Pairs Not matched pairs Let's pick those..

  15. Mike Bachtis / UW The study • The trigger rules are: • Et of the two most energetic jets > threshold • Delta Phi is between 2 and 4. • For the definition of threshold the data were run for different possible threshold values along with the default trigger. • A small QCD sample 1500 events was tested (Pt 40-170). • We check trigger efficiency, QCD efficiency and fake ratio(not matched/good) as indicators of performance.

  16. Mike Bachtis / UW The new approach provides similar efficiency with lower Fake ratio and QCD background. The threshold depends on the rates. A threshold of Et>15GeV seems good (improves efficiency by 20% but also QCD efficiency by the same factor!)

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