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Muon Efficiency and Background Analysis for Z to tt Decay: Challenges Ahead

This document explores the workflow for analyzing muon efficiencies and backgrounds in the decay process of Z to tt, specifically focusing on muon isolation, track matching, and the identification of hadronic tau signatures. Utilizing various methods such as preselection and trigger efficiency evaluations, the analysis aims to enhance the understanding of acceptance and reconstruction efficiencies. It highlights the importance of accurate background assessment from Zmm and Wmn channels and sets the stage for further studies to refine the findings and optimize cut efficiencies in muon tracking.

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Muon Efficiency and Background Analysis for Z to tt Decay: Challenges Ahead

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  1. Z -> tt -> m had • Preselection • Efficiencies (muon) • Backgrounds + Cuts • Trigger • Back to the Tau • ..and what remains to be done Z  tt  m had

  2. The Muon: medium track match (Saclay, not axial) use central track momentum pT > 15 GeV (at first) for signal: muon isolation The Tau Tau object with >=1 track not the same object as muon Preselection Z  tt  m had

  3. Muon efficiencies • acceptance*pT • reconstruction • track match • trigger • L1 • L2 • timing Z  tt  m had

  4. Muon acceptance*pT • use Z mm MC • use MC reco-eff to define region “where detector is” • use generator level MC to determine acceptance*pT cut • smear Gen-level pT to reproduce Z-width (W mn measurement) Z  tt  m had

  5. Muon Reco-Efficiency • Use di-m events in mutrk-skim • Require events to have Trigger w. 1 L2 m • Tagging m of medium quality w. track, matched to L2 m -> 2nd m unbiased • Second m track (+cal), invariant mass of dimu: Z or J/psi Z  tt  m had

  6. Muon Track*Match Efficiency • Use two methods: test+tag + count #evts. with 0,1 or 2 matches • Use J/psi + Z peak • Start from di-mu stream, require two medium muons Z  tt  m had

  7. Muon Trigger Efficiency - L1 • Use top muTrig skim • Check L1 AO terms Z  tt  m had

  8. Muon Trigger Efficiency- L2 • Require L1 all • For L2: look at global m, match to offline m, compare L2M0 req. Z  tt  m had

  9. Muon Trigger Efficiency- L3 • Copy WZ-results: • Req. L2M5 • Use Z mm events, treat each m as seed for W event • Trig-sim event+ check L3 track Z  tt  m had

  10. Muon Timing Efficiency • Use MuoCandidate • Cosmic-rejection using A+BC layer times • Look at dimu-triggered events w. 2 med, trk muons, count evts in peak that have 0,1,2 mu in time Z  tt  m had

  11. Muon Isolation • Consider tracking + calo-based isolation variables • Get efficiency+rejection numbers from Z+QCD samples • Z: two med+trk in mass window • QCD: p13 MET < 10 GeV Z  tt  m had

  12. Muon Isolation (II) Z  tt  m had

  13. Backgrounds - Zmm • Zmm • Rejection in 3 steps • No other loose mu • No cal+trk in Z window • No isolated track w. pT > 15 in Z window • Use data Z to estimate eff. of cuts Z  tt  m had

  14. Backgrounds - Wmn • Wmn • Rejection using transverse mass • And MET • No eff estimation from data yet Z  tt  m had

  15. Data - Wmn Z  tt  m had

  16. The hadronic tau • Look at profile (ET1+ET2)/ET • Look at trigger events “came in” on • Require L2M0-term • determined eff • basically un-prescaled Z  tt  m had

  17. The hadronic tau - Bkg. • Background sample: • Cuts->shape? Z  tt  m had

  18. The hadronic tau - And Cuts • Look at ettr: • Sum pT of add tracks in 0.5 cone Z  tt  m had

  19. The hadronic tau - And Cuts • Look at ettr: • Sum pT of add tracks in 0.5 cone • add iso Z  tt  m had

  20. The hadronic tau - And Cuts • Look at ettr: • Sum pT of add tracks in 0.5 cone • add iso • Add profile Z  tt  m had

  21. The hadronic tau - And Cuts • Look at ettr: • Sum pT of add tracks in 0.5 cone • add iso • add profile • and look at tracks… Z  tt  m had

  22. The hadronic tau - NN • For people who like neural nets even if these are trained on MC that does not describe the data…. Z  tt  m had

  23. The hadronic tau - cal pT To see just just low energy “stuff” Check track pT, look very similar Z  tt  m had

  24. What remains to be done… Divide into types and look at Et/pT Invariant mass -> debug code Factor opp sign - like sign -> numbers of events Expected # events -> use eff numbers from data Z mm background -> practically done Efficiency of cuts on tau - have to use MC Use CTF p13.08 MC - about ready (and as soon as QCD availible check if background is decribed….) Z  tt  m had

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