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Progress on H/Abb -> 4b’s channel for the FTK physics case ~ 4jets Trigger w/ and w/o FTK ~

Progress on H/Abb -> 4b’s channel for the FTK physics case ~ 4jets Trigger w/ and w/o FTK ~. Kohei Yorita Young-Kee Kim University of Chicago @ the FTK Meeting on October 19 th , 2006.

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Progress on H/Abb -> 4b’s channel for the FTK physics case ~ 4jets Trigger w/ and w/o FTK ~

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  1. Progress on H/Abb -> 4b’schannel for the FTK physics case~ 4jets Trigger w/ and w/o FTK ~ Kohei Yorita Young-Kee Kim University of Chicago @ the FTK Meeting on October 19th , 2006

  2. Review of 4J Trigger (MC) We have looked at many variations of MC samples. > Sherpa - version (patch) change - different configuration - yt cut - w/ and w/o UE > Pythia - v6.2 (v10 Athena) - v6.3 (v11 Athena) Now it is time to decide “default” sample to conclude studies. (whatever it is, big unknown factors (always) still remain.) Now Default Sample : SHERPA 2->3, yt>25 ; 10M events

  3. Systematics on MC Choice Again, Default Sample : SHERPA 2->3, yt>25 ; 10M events Comparison to 2->2+3+4 Comparison of yt cuts Correlated & poor stat. 10% systematics 5% systematics

  4. Comparison to PYTHIA Pythia 6.2 Pythia 6.3 Old UE/MI New UE/MI Pt>15 : +-30% x3~4 Pt>20 : +-30% x2~3 Pt>50 : +-20% x~1.4 > Big Unknown : UE/MI tuning. > Why v6.3 changes so much by Ptcut ? > My Signal sample (H/Abb) is still v6.2. - so we should take +- 30%. So total is ~32%. Might differ by ~2-3 though.

  5. Default Sherpa sample is w/o UE. Erik generated ~2M events w/ UE. Because some jobs are crashed and slow?, Here trying to get Scale Factor here. Issues on Underlying Events After correction, fluctuation is at the level of 3-5% which is negligible compared to other systematics (~32%). Fit : Expo+Linear Functions From 20 GeV to 120 GeV.

  6. Finalizing Trigger Rateas a function of ATLFAST Pt So new working points : - 30 GeV (w/ FTK) and 50 GeV(w/o FTK). OLD setting : - 40 GeV (w/ FTK) and 70 GeV (w/o FTK) -> All studies had to be redone ! 1KHz (w/ FTK) 100Hz (w/o FTK) * This is what we get with our current best knowledge. 30 50

  7. Based on LVL1 8x8 Calorimeter Parameterization UE scale factor 1KHz (w/ FTK) 200Hz (w/o FTK) @LVL1, w/ FTK (1KHz) : 25 GeV Then btagging @LVL2 w/o FTK (200Hz) : 35 GeV Then Jet Pt>50-60 @LVL2 25 35

  8. Summary of Trigger Rates & Threshold LVL1 Calo vs Atlfast Pt Correspondence * For Atlfast Jets, Assuming LVL2 Jet =~ Atlfast Jet • We need LVL2 reduction • rate of 10 by either • > Btagging (wFTK) > Raising Pt thresh (w/oFTK) Is it possible (by FTK) ? Need mistag rate. (next page.)

  9. Issues on LVL2 Reduction • The reduction rate depends on trigger strategy : • i.e. btagging is applied for means • Only Leading jets. (e.g. 4b for 4 leading jets) OLD • Any fiducial jets (eta<2.5) NEW (1) Updated to (2) Not straightforward like linear behavior.

  10. LVL2 Reduction (Cont.) > It depends on the number of fiducial jets and real b quark contents. > Pythia and Sherpa are not much different. But it seems PYTHIA gives lower reduction i.e. it has either more fiducial Jets or/and more real b quarks. With FTK btagging at LVL2, We need a reduction factor of >10 in order to keep Jet Pt threshold. So the following condition would be enough : > 2tag if Ru > 10 (10% mistag) > 3tag if Ru > 4 (25% mistag) > 4tag for any Ru (>2) better Working point in this talk.

  11. Let’s Look at Signal Process > bb decay : ~85-90% iftan>20 Coupling to up-type is enhanced at low tan, so decay into tt becomes large. Cross section  BR (pb) (each sample was generated with Atlfast simulation)

  12. Signal Gain @ Trigger Level

  13. Signal Gain @ Trigger Level (Cont.) Still expected N of background is ~1.5x10^9. So for the analysis, we have to optimize selection criteria.

  14. What if Trigger Rate is x3 higher ? If Trigger (Background) rate is x3 higher, Thresholds have to be raised accordingly to keep LVL1 rate(1KHz) and LVL2 rate(100Hz). -> This is good study for uncertain QCD bkg & higher luminosity (10^34). We lose signal acceptance, but relative improvement looks even powerful.

  15. (Offline) Optimization based onw/ and w/o FTK Conditions > Requiring btag for “leading 3/4jets” for 3/4btags. > 1st,2nd ,3rd jet thresholds are optimized for different MA separately. > 4btag is more powerful than 3btag.

  16. (Offline) Optimization based onw/ & w/o FTK Conditions Now results are not so good as before (which is more or less same as right plot (x3 bkg).). But I think that the most important thing is that even if the background rate is much higher due to high lum or MC miscalculation (in this case, x1 or x3) , FTK can provide almost same sensitivity ! But without FTK, very weak against higher background (compare dotted line.)

  17. Plan > Again, need inputs of realistic btagging efficiency and mistag rate to conclude. (Now @LVL2, 2tag with effb=50%, Ru=10 is required in order to reduce the rate by 10 (1KHz->100Hz).) • > Missing Pieces : • - Complete & Summarize Multi-Threshold Study. • - Dijet Mass Distribution > Document it ! > FTK Simulation ?

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