1 / 22

Motivation

Fact: The multi-generational structure of the quark doublets requires explanation and could herald compositeness. Motivation. CDF: PRL 82 (1999) 2038. Under hypothesis of compositeness, deviation from point-like behavior would likely manifest in third generation.

don
Download Presentation

Motivation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fact: The multi-generational structure of the quark doublets requires explanation and could herald compositeness. Motivation CDF: PRL 82 (1999) 2038 Under hypothesis of compositeness, deviation from point-like behavior would likely manifest in third generation. Conclusion: g  bb may exhibit desired deviant behavior. Explore b quark dijet mass as a possible signature. • Problem • ~100:1 QCD:bb Solutions • m tagging • 2nd VTX tagging • Impact parameter Fit to CDF qQCD calculation

  2. eT Trigger Eff ePV Primary Vertex Eff ej Jet Eff emm Eff fbm Frac b  m(Pt > 4 GeV) fBm Frac B  m(Pt > 4 GeV) L Luminosity Dpt Pt bin width sb b cross-section sB BKD cross-section m-tagged Jet Cross-section Correlated Jet + m (Pt > 5 GeV) • Given the simplicity of the calculation, there are few likely sources of the excess seen in p13. These could conceivably be • N • m JES (central value) • Resolution (i.e. smearing) p13

  3. p14 Analysis Summary • Inclusive m-tagged jet • corrJCCB (0.5 cone jets) • Standard Jet quality cuts, Standard JET Triggers • Jet tagged with MEDIUM muon • (more on this later) • DR(m, jet) < 0.5 • |yjet| < 0.5 • JES 5.3 • Long term goal was b-jet xsec. Difficult due to no data-driven determination of b-fraction.

  4. p14 Skimming • Start with CSG QCD skim • Turn into TMBTrees (40M events…on disk) • Skim on Trees • Remove bad runs (CAL, MET, SMT, CFT, JET, Muon) • Remove events w/o 2 jets • Use Ariel d0root_ based package • SKIM 1:  1 leading jet has ~ MEDIUM m (P(m) > 4 GeV) • SKIM 2:  1 leading jet has ~ loose SVT

  5. p14 All Data: CSG Skims Bad runs & lumblk removed in luminosity. Only bad run removed in event counts for skims. Up until Run 193780 (07-JUN), V12.37.

  6. Trigger Turn On • Jet Trigger • Collinear muon • |yjet| < 0.5 • Luminosity weighted • Statistics uncorrelated poisson • (wrong, of course) • JES corrected (5.3)

  7. f Distribution of MEDIUM m-tagged jets (+ mycuts) f(jet+m) These cuts clearly improve the fake m rate. Some residual fake m’s must persist. How many? CHF should be higher for punch through jets?

  8. Closer Look Suspicious JT45_TT Pt(m) 4.5-5.0 4.0-4.5 Pt(m)

  9. What is now a muon? • Medium muon (as defined by mID group) • At least one scintillator hit in BC. • Pt(central track) > 5 GeV • |Pt(central) – Pt(global)| < 15 GeV • Rejected if • 4.25 < f (muon) < 5.15 AND • |h(detector)| < 1.1 m A layer cal jet Fake m from punch-through In a jet environment is an issue

  10. Efficiency/Fraction Summary

  11. m JES Definitions • Required identically 2 jets • Pt(jet 3, uncor) < 8 OR third jet doesn’t pass jet QC • One jet contains muon, the other doesn’t. • | Df | > 2.84 • Imbalance variable: • Independent variable:

  12. JES v5.3 STD JES 5.3 gives a 3.8% offset for m-tagged jets. It is independent of Pt (75-250 GeV). Maybe higher above that. Need to rebin and revisit the idea that the muon Pt may be mis-measured. Same plot when scaling the m-tagged jets by 3.8%.

  13. JES v5.3 Energy Resolution(Fixed)

  14. Fitting Functions

  15. Extraction of Correction Factors “normal” exponential

  16. Point by Point Unsmearing Factors “normal” Exponential Unsmearing Error small ~5% for Pt > 100 GeV

  17. PtRel at High Pt PtRel muon jet

  18. Fitting to HF fraction

  19. Systematic Error Breakdown

  20. MC Comparison • Pythia using standard DØ MC. • NLO uses NLO++ (CTEQ6L) • From Pythia, find fraction of jets tagged with muons (HF only). • Multiply NLO cross-section by Pythia muon-fraction. • This is effectively the NLO k factor.

  21. Status • DØNote and Conference note to EB025 • Residual small bug in code (should have only a few percent effect). • JES error must be reduced to use this before setting limits on new physics.

More Related