1 / 40

Validation of DC3 fully simulated W → e ν samples with an eye to strange sea asymmetry analysis

Validation of DC3 fully simulated W → e ν samples with an eye to strange sea asymmetry analysis. Laura Gilbert 11/09/06. W → e ν from MC@NLO, full sim.

rosie
Download Presentation

Validation of DC3 fully simulated W → e ν samples with an eye to strange sea asymmetry analysis

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. Validation of DC3 fully simulated W→eν sampleswith an eye to strange sea asymmetry analysis Laura Gilbert 11/09/06

  2. W→eνfrom MC@NLO, full sim • Original sample submitted for generation in December, some of the one million W→e-ν now fully simulated on the grid, in batches of 10k events. • (NLO, reconstructed in 11.0.42) • 47800 events available (using CBNTs) • Lepton generator level filter efficiency (10Gev, |η|<2.7) was ~63.3% • Generated cross section is 8.4nb (cf. 30nb for W→l-ν: TDR). Luminosity for 10k events is 1.9pb-1. • Cuts applied at any stage are listed on top right of slide. • ALL truth plots are normalised to weighting of simulated data EXCEPT multiplicity plots.

  3. ELECTRONS Sanity plots: multiplicity - truth - full sim

  4. Electron Selection Cuts • At least one electron with transverse energy > 25GeV. (Use ET rather than pT since brem recovery not properly implemented yet0 • Electron candidate has at least one associated track matched (exclude photons) • η < 2.4. This cuts out dubious candidates at the end of the electromagnetic calorimeter. • IsEM flag = 0, electron isolation cut. This should now be tuned correctly but I need to look into the bitwise cuts in more detail to check.

  5. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS Sanity plots: multiplicity of electrons that pass selection cuts - truth - full sim Almost always only one electron candidate per event passes cuts.

  6. ELECTRONS Checking cuts with truth info: Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 Initially tracks of candiadates entered into egamma container include kaons, pions, muons. After cuts only electrons remain. - before cuts - after cuts

  7. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS Sanity plots: phi - truth - full sim

  8. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS Sanity plots: eta - truth - full sim

  9. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS Identifying electrons with their partner in truth containers, matching (η,φ) space: If (ΔR<0.1) match is found

  10. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS Sanity plots: ET - truth - full sim

  11. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS Difference between simulated and truth ET distributions: PROBLEM? No overall difference between simulated and truth ET shapes!

  12. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 • ΔR<0.1 (matching sim to truth) ELECTRONS Electron ET resolution: (sim-truth)/truth for matched sim:truth electron pairs. Resolution looks roughly ok though…

  13. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS "Wrong sign" electrons found from associated track q/p, AFTER cuts: Wrong sign Correct sign *PROBLEM*

  14. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRONS ET distribution of "wrong sign" electron candidates: - +ve charge electrons (from track q/p) - all electron candidates (for shape comparison)

  15. Cuts: • ET (ele truth) > 25GeV ELECTRONS Consider truth information: just cut on ET > 25GeV There are positrons present in egamma truth, but none pass ET cut. - before cuts - after cuts

  16. ELECTRONS • What are the wrong sign electrons? • Not generated positrons • Don't have high pT tracks, so probably not electrons mis-reconstructed. • Possibly wrong track-cluster combinations. Needs further investigation.

  17. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • η(ele) < 2.4 ELECTRON ISSUES • Further investigation needed: • E over p always 0! → needs to be fixed in future. • Where do the "positrons" come from? • Need to look into IsEM flags in detail.

  18. ELECTRON JETS W Transverse mass plots look fishy if I apply exclusions on events containing jets with ET>30GeV. Therefore many jets come from electrons. Identify and exclude these electron jets. Can only be one on jets with η<2.5 to make electron matching possible. (Jets reconstructed using cone algorithm with R<0.7, see later)

  19. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • Jet η < 2.5 ELECTRON JETS Matching electrons and jets in (η,φ) space: - truth - full sim Log scale→ Identify jets with electrons if ΔR<0.7

  20. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • Jet η < 2.4 ELECTRON JETS Matching electrons and jets in energy: Trying to match energy as well as (η,φ) distribution (no cut made): Jets are corrected to have more energy than electron candidates so -ve values more likely to be a match. - truth - full sim

  21. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • Jet η < 2.4 ELECTRON JETS A closer look at electron-jet ΔR and energy distributions: simulation Smattering of events here

  22. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • Jet η < 2.4 ELECTRON JETS A closer look at electron-jet ΔR and energy distributions: truth no events here

  23. Cuts: • ET(ele) > 25GeV • At least one track matched • IsEM=0 • Jet η < 2.4 ELECTRON JETS A closer look at electron-jet ΔR and energy distributions: (truth - simulation) Truth - simulated This is the normalised difference of the last two plots! Energy difference (MeV) ΔR

  24. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS • Looking at all jets which have not been matched with electrons: ie. Jets which are isolated from electron candidates by at least 0.7 in (η,φ). • Still looking at jets with η<2.4 for accurate electron matching. • There are three available clustering algorithms: • Kt alorithm: apparently unsuitable for low pT jets. • Cone algorithm with R<0.4. Discounted as produces very low statistics (few jets reconstructed) • Cone algorithm with R<0.7. Use this.

  25. JETS Sanity plots: multiplicity before any selection: - truth - full sim

  26. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS Sanity plots: multiplicity after electron/jet matches removed, jet η<2.4 - truth - full sim Log scale→ Multiplicity greatly reduced

  27. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS Sanity plots: phi - truth - full sim

  28. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS Sanity plots: eta - truth - full sim Shape before η cut

  29. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 • ΔR(jet-truth)<0.5 JETS Matching jets with truth in (η,φ) space: Log scale→ If (ΔR<0.5) match is found

  30. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS Sanity plots: ET - truth - full sim Jets not reconstructed < 10GeV

  31. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 • ΔR(jet-truth)<0.5 JETS ET resolution: (sim-truth)/truth

  32. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS Sanity plots: Energy - truth - full sim

  33. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 • ΔR(jet-truth)<0.5 JETS Energy resolution: (sim-truth)/truth

  34. Cuts: • ΔR (e-jet) > 0.7 • Jet η < 2.4 JETS Sanity plots: ET - truth - full sim Strange: data is shifted down from truth.

  35. JET ISSUES • Jets from electrons are easily identified and removed by an exclusion cut in (η,φ) space. • Not certain this is the best algorithm, but other available algorithms have more problems. • Jet statistics low after removal of electrons, therefore resolutions not well defined. • Meaning of jet “mass” not well understood, left-shift of simulation w.r.t. truth unexpected.

  36. Cuts: • Ptele > 25GeV • At least one track matched • IsEM=0 • Electron η < 2.4 • Jet η < 2.4 • ΔR (e-jet) > 0.7 • MET>25GeV MISSING ENERGY Sanity plots: Missing ET Probably not properly calibrated - truth: calculated from non-interacting particles - full sim: corrected, inc. muons Cut on MET>25GeV

  37. Cuts: • Ptele > 25GeV • At least one track matched • IsEM=0 • Electron η < 2.4 • Jet η < 2.4 • ΔR (e-jet) > 0.7 • MET>25GeV MISSING ENERGY Missing ET Resolution: Asymmetry reflecting right-shift of data w.r.t. truth

  38. Cuts: • Ptele > 25GeV • At least one track matched • IsEM=0 • Electron η < 2.4 • Jet η < 2.4 • ΔR (e-jet) > 0.7 • MET>25GeV MISSING ENERGY Missing ET φ distribution: - truth - full sim

  39. Cuts: • Ptele > 25GeV • At least one track matched • IsEM=0 • Electron η < 2.4 • Jet η < 2.4 • ΔR (e-jet) > 0.7 • MET>25GeV W RECONSTRUCTION W transverse mass reconstructed from Missing ET and highest ET electron: - truth - full sim

  40. Conclusions: • The W looks like TDR (right)! • Electrons are well reconstructed. • The e/p variable in the egamma container should probably be fixed. • Electrons with mis-identified charge not yet understood. • Missing energy doesn’t seem best corrected to match truth. • Insufficient stats for decent jet resolution. • Jet “mass” shift seems strange.

More Related