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Tau MET Corrections Update

Tau MET Corrections Update. Alfredo Gurrola (Texas A&M) JetMET Meeting: August 21, 2007. Tau MET Corrections (Update). Current Packages use corrected CaloJet information based on the jet response, CaloJet E T / GenJet E T (as a function of Jet E T and h) ,

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Tau MET Corrections Update

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  1. Tau MET Corrections Update Alfredo Gurrola (Texas A&M) JetMET Meeting: August 21, 2007

  2. Tau MET Corrections (Update) • Current Packages use corrected CaloJet information based on the jet response, CaloJet ET / GenJet ET (as a function of Jet ET and h) , to determine the corrections to Jets and MET • Basic goal is to use the information provided by Particle Flow (PF) to determine the proper way to make corrections to MET • PF t jet response & resolutions as a function of t ET and h • MET w/o and with t corrections • Determine the best way to implement the t MET corrections

  3. Tau MET Corrections (Update) Tau MET Corrections (Update) • Let’s take a look at t PT resolutions! • CMSSW_1_6_0_pre4 • W tn sample of 90,000 events • |ht| < 2.5 for generator level taus • Compare PT resolutions for: 1. t jets reconstructed using IterativeCone5CaloJet algorithm 2. t jets reconstructed using IterativeCone5CaloJet algorithm with energy corrections based on jet response as a function of ET and h 3. t jets reconstructed using Particle Flow (PF) and tagged using RecoTauTag/PFConeIsolation Package which discriminates between t jets and QCD jets based on the narrowness of t jets NOTE: The MC t must be matched to BOTH the PF t and the InterativeCone5CaloJet

  4. Tau MET Corrections (Update) • To make comparisons to MC t’s, a definition of a ‘match’ is required • Look at DR between PF t’s and MC t’s • Look at DR between Calorimeter Jets and MC t’s • Define a match between PF t’s and MC t’s : DR < 0.1 • Define a match between IterativeCone5 Calorimeter t jets and MC t’s : DR < 0.2 IterativeCone5 t Jets PF Jets tagged as t’s Jets that are NOT t’s

  5. Tau MET Corrections (Update) • What is the t jet PT resolution for PF & how does it compare to the current jet resolutions (Calorimeter Jets & corrected CaloJets)? • Not only is the PT resolution better for PF, but the distribution is now peaked at 0! • Because of the longer tail in the PF distribution, RMS is NOT a good indicator of the PT resolution • Note: Distributions contain t’s of ANY visible energy & h (Statistics are dominated by low PT) IterativeCone5 t’s PF Corrected IterativeCone5 t’s

  6. Tau MET Corrections (Update) • Since the statistics are dominated by low PT, the previous plots do not show the PT dependence. • Is there a PT dependence? IterativeCone5 t’s Corrected IterativeCone5 t’s PF

  7. Tau MET Corrections (Update) TAIL!! • How do the resolutions compare at low PT? • Once again, we can see that PF has better resolution. • Tails of the PF distributions are caused by double counting in PF code! • Once these bugs are fixed, we should see less effect of the tails on the RMS IterativeCone5 t’s Corrected IterativeCone5 t’s PF

  8. Tau MET Corrections (Update) • How do the resolutions compare at high PT? • At high PT, we really begin to see the huge differences in PF resolution • However, we still have the tails! IterativeCone5 t’s Corrected IterativeCone5 t’s PF TAIL!!

  9. Tau MET Corrections (Update) • Let’s take a look at MET corrections for t’s using PF! • Event Selection • W tn sample • |ht| < 2.5 • Njets(QCD) = 0 with PT > 5 GeV • Correct Missing Energy if Monte Carlo t has PT > 15 GeV NOTE: The MC t must be matched to BOTH the PF t and the InterativeCone5CaloJet

  10. Tau MET Corrections (Update) Before ME Corrections PF t ME Corrections Corrected CaloJets Missing Energy projected onto standard x axis and y axis • Missing Energy corrections for t’s using PF have better resolution • There is a HUGE difference in resolution between Missing Energy Corrections using PF t’s and Corrected IterativeCone5CaloJets • NOT much difference between Uncorrected ME and Corrected ME using PF. The reason is because we are dealing with low PTt’s (tails also affect resolution)

  11. Tau MET Corrections (Update) TAIL!! • MET Resolution • Peak Position and resolution is better for MET corrections with PF t’s • The distribution for PF t MET corrections is narrower in the central parts of the distributions • However, the RMS is affected by the tails in the PF distributions (double counting) Before MET Corrections PF t MET Corrections MET Corrections with Corrected CaloJets

  12. Tau MET Corrections (Update) • There is HUGE improvement between standard “jet based” MET corrections and PF t MET corrections • However, there is NOT much improvement between the distributions with PF t MET corrections and those without any MET corrections • The reason for this small (if any) improvement is that for W tn we are dealing with low PT taus • Let’s take a look at higher PT taus (larger MET) • H tn sample of 20,000 events • |ht| < 2.5 for generator level taus • Correct Missing Energy if Monte Carlo t has PT > 50 GeV

  13. Tau MET Corrections (Update) IterativeCone5 t’s PT Resolution Corrected IterativeCone5 t’s PF

  14. Tau MET Corrections (Update) • MET Resolution • Peak Position is better for MET corrections with PF t’s • Resolution for PF t MET corrections is worse than the resolution without t MET corrections, but better than the resolution for standard “jet based” MET corrections using IterativeCone5CaloJets Before MET Corrections MET Corrections with Corrected CaloJets PF t MET Corrections

  15. Summary

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