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Jet Properties, Data-MC with all Aleph Data

Jet Properties, Data-MC with all Aleph Data. Jet Mass Angles @ Lep1 Z Lep2 Z, W & Z g. Aims:. to investigate general Data-Mc agreement to check consistency of ‘picture’ between different data samples

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Jet Properties, Data-MC with all Aleph Data

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  1. Jet Properties, Data-MC with all Aleph Data Jet Mass Angles @ Lep1 Z Lep2 Z, W & Zg Ann Moutoussi, CERN

  2. Aims: • to investigate general Data-Mc agreement • to checkconsistencyof ‘picture’ between different data samples • to find a way toextract correction factors and/orsystematic shiftsfrom control samples (eg Z’s) and apply on W’s.

  3. The different Samples: Z’s @ LEP1, LEP2 • LEP1 Z :1994 Data and Latest Jetset MC • Reconstruction: All EFLOW, REPG • Selection: Franco’s Thrust>0.8, Ech>10 • ~500K • Lep2 Z :e.g 1998 Data and Jetset • Reconstruction: All EFLOW • Selection: Franco’s • ~100K per year

  4. The different Samples: W’s and Zg All LEP2 data & New MC: Koralw3, KK2F, ZZ, Pz (no Wev,gg) • W’s : All EFLOW • 4q: ~3.5K • NN14, trainings ala CN, cut=0.3 • Typical selection -to ensure good pairing: Standard Kinematic Fit, Pairing, window and final selection according to 4C-Rescaled Mass (60-86, 74-86) (I.e identical to ‘traditional’ measurement) • 2q: ~3.5K • Selections ala CN • Loose further selection -to avoid Wev,gg, Mhadronic>60GeV (I.e not identical to mass measurement where tighter windows on fitted properties are imposed) • Zg: Reconstruction and basic Selection: Eugeni: ~26K • No LCAL, SICAL & No ‘bad’ tracks, i.e V0 s • Mvis>50, Locking of g • Loose window -to avoid gg, 120>Mhad>60 (Standard cut on x: 0.6-0.88)

  5. Comment on Jet Mass at Z’s (1) • Previous meeting different numbers (~20-~100MeV) • Different samples, (W’s, Z’s, Zg) or Same samples - different Selections e.g Thrust cut on Z events: Jet Mass and Data-MC agreement vs Thrust Cut Jet Mass 1)Jet Mass and Data-MC depend on Thrust 2)JetC: difference ~50MeV Data-Mc No JetC With JetC

  6. Z: T>0.8 Z:T>0.95 Zg W: 2Q Comments on Jet Mass at Z’s (2) • Which Thrust selection more appropriate for W’s? No selection identical, but high Thrust less similar. For remaining: keep 0.8

  7. Comment on Jet Mass at Z’s (3) • But.. Still Data-MC less than 100 MeV Jet Mass and Data-MC agreement vs Thrust Cut with & without REPG: g calibration like LEP2 Jet Mass No Jetc Use REPG etc with LEP1 Data-Mc Difference ~20-40MeV With JetC (same)

  8. Jet Mass Variation: Data-MC agreement vs Pcut Charged Jet Mass (no JetC) Z:  1994 (~500K)  1998 (~100K) 4Q 2Q Zg Compatible behavior?? What could make it different ?? Different EFLOW:Track Selection.. (e.g no V0’s)

  9. Jet Mass Variation: Data-MC agreement vs Pcut Jet Mass (With JetC) Z:  1994 (~500K)  1998 (~100K) 4Q 2Q Zg Scale.. (Different EFLOW:Track Selection + No LCAL/SICAL)

  10. Any other dependence of Jet Mass and Data-MC? Zg Z :1994 Data-MC Jet Mass vs Cos(Q) (Standard EFLOW) No JetC With JetC

  11. So…how compatible are Z’s,W’s & Zg’s ? • Z: Lep1 similar trends to Lep2. Maybe larger shifts at Lep2? (15 10 vs 50 25) • Combine all LEP2 Z (1998+1999+2000) • If we trust Z’s… Systematic at Pcut=0 and Pcut~1: same size, opposite sign… • 4Q: similar trends & Shifts within 1s to Lep2 Z’s.(7055) • 2Q: larger shifts, but within 2s to Lep2 Z’s. (21090) • + Caution: Selection sensitive (to be checked/use Mass analysis Windows) `Forgot’ some bkg? Any chance for splitting by channel? • Zg ~similar trend. • Check effect of different reconstruction? • Some Dependence with Q? (use full LEP1 data?) • Basically compatible….Propagate shifts.. With care!

  12. Angular Biasses… at W’s and Zg’s... Jet direction Neutral* Objects Vector Charged Objects Vector • As always use different Jet components as a tool: Can Measure Q(charged-charged): Qch Q(all-all) : Qa Q(neutral-neutral) : Qn Q(all-charged) : Qach Q(all-neutral) : Qan and the differences (Qch- Qa),(Qch- Qn) etc for Data and MC and construct double difference eg: [(Qch- Qa)]Data - [(Qch- Qa)]MC * in following Neutral=type 4+type5 Eflow

  13. Angular Biasses… 1)at W’s... MC Charged Qch Data Charged Qch MC all Qall Data all Qall 4Q 2Q  All Ch. Pcut Pcut

  14. Angular Biasses… at W’s... [(Qch- Qa)] AsQdepends on Mw look at differences: [(Qch- Qa)]Data , [(Qch- Qa)]MC [(Qch- Qn)]Data, [(Qch-Qn)]MC Points Data Histo MC 4Q 4Q 2Q 2Q (all EFLOW)

  15. Angular Biasses… at W’s…Double Differences [(Qch- Qa)]Data - [(Qch- Qa)]MC [(Qch- Qn)]Data - [(Qch-Qn)]MC Mean Difference vs Pcut: 4Q 4Q ~1 mrad ~-2 mrad ~-4 mrad 2Q ~-12 mrad 2Q

  16. Angular Biasses… Summary at W’s... MC Charged Qch Data Charged Qch MC all Qall Data all Qall • Going from All to Charged Di-jet Angles get smaller for • both channels, Data&Mc • but.. In Data they get Smallerer than in MC.. (~3mrad) • Charged Only measurement will be smaller… • (especially true for semileptons.. Check selections etc..) • Biass seems flat & does not depend on Pcut. • But which is -more- correct.. Charged or All/Neutral?

  17. MC Charged Data Charged MC all Data all Angular Biasses… 2)at Zg’s... 2Q Zg  All Ch. 1)Not same ordering! Is it the different Reconstruction? Pcut Pcut

  18. MC Charged Data Charged MC all Data all Angular Biasses… 2)at Zg’s... • Both Components shifted… • towards lower EcM. • Similar results for charged/All analysis… (to be checked again?) • Can the tracks be wrong!?!? Pcut

  19. Angular Biasses… at Zg’s…Double Differences [(Qch- Qa)]Data - [(Qch- Qa)]MC [(Qch- Qn)]Data - [(Qch-Qn)]MC Mean Difference vs Pcut: 4Q 4Q ~2 mrad ~-6 mrad Pcut Pcut

  20. Angular Biasses… Summary... • W: • Cannot tell if Charged/Neutral more wrong. • Can use difference as an estimate of angular biass. • Semileptonics seem more affected… • again to check selections etc. • Difference charged-neutral to be propagated. • Zg: If we believe Elep: • Could be used to tell if charged/neutral better.. • Ordering of angles not as in W’s. (Charged angle larger than EFLOW angle) • Check reconstruction • Check with Paolo angular differences

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