1 / 16

Progress on the FTK Physics Case (For H/Abb 4b signal)

Progress on the FTK Physics Case (For H/Abb 4b signal). Contents. Brief Sample Descriptions LVL1 Rate & Threshold Estimation (3) “Rough” Significance Estimation (w/o FTK) (4) Summary & Plan. Kohei Yorita

soyala
Download Presentation

Progress on the FTK Physics Case (For H/Abb 4b signal)

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. Progress on the FTK Physics Case(For H/Abb 4b signal) Contents • Brief Sample Descriptions • LVL1 Rate & Threshold Estimation • (3) “Rough” Significance Estimation (w/o FTK) • (4) Summary & Plan Kohei Yorita Young-Kee Kim University of Chicago @ FTK Meeting on January 26th , 2006

  2. Samples used for the analysis > All has been done using Atlfast simulation, except for Erik’s L1 Parameterization(derived from full simulation) > Signal H/Abb -> 4 b’s : generated with Pythia, whereMA = 500 GeV,tan = 30. (Xsec ~4 pb) > Backgrounds : - Pythia dijet samples (minPt cut = 10-90 GeV). - Pythia bbbar samples (minPt cut = 10-90 GeV). - Pythia ttbar * SHERPA samples available from Erik. (not in this talk.) Note : typical Xsec for dijet ~ b (> 10^6 larger than signal)

  3. Comparisons of 2 Generators with 4j at 40 GeV

  4. Trigger Turn-on Curve Atlfast jet Et LVL1 8x8 Et cut @ 40 GeV > At 95% efficiency ; LVL1Et = ~0.82 * AtlfastEt – 32. > At 50% efficiency ; LVL1Et = ~0.92 * AtlfastEt – 24.

  5. J1 : Single Jet Trigger @ L=2x1033 200 Hz 200 Hz 20 Hz 20 Hz No phase space No statistics 200 Hz (LVL1 out): Jet Et > ~ 200 GeV, 8x8 Calo > ~ 160 GeV 20 Hz (HLT out) : Jet Et > ~ 350 GeV, 8x8 Calo > ~~

  6. J2 : 2 Jets Trigger Rate @ L=2x1033 200 Hz 200 Hz 20 Hz 20 Hz It seems current trigger requirement (20Hz @ HLT) 100% prohibits us from working on Jet calib. using Z (->bb) mass peak.

  7. J3 : 3 Jets Trigger Rate @ L=2x1033 200 Hz 200 Hz 20 Hz 20 Hz > Looks very challenging to obtain even Z(->bb)+ high pt jet events. Needless to say, would be really nice if we could lower thresholds ! > Relevant trigger for our signal, H/Abb, H->hh analysis

  8. J4 : 4 Jets Trigger Rate @ L=2x1033 200 Hz 200 Hz 20 Hz 20 Hz > Statistics not enough. Need to generate more. > Should check with SHERPA samples. > Baseline trigger for the H/Abb, H->hh, 4jets analysis

  9. Corresponding Points w.r.t. Trigger Rate 2J @ 0.2KHz These two variables correspond between 50 ~ 90% efficiency line w.r.t. trigger rate. 2J @ 2 KHz 1J @ 0.2KHz 2J @ 20 KHz 1J @ 2 KHz 1J @ 20 KHz

  10. All(J1,J2,J3,J4) in one together Using Ptmin=30 GeV dijet sample 200 Hz 200 Hz 20 Hz 20 Hz Requiring another jet with the same cut value makes LVL1 rates reduced by a factor of 10. (only true for 2->3->4 (dijet events))

  11. Other processes: bb/tt productions • Very small cross section compared to dijet events, • LVL1 rate from these two is negligible (~ 1% contribution) • - but become important when btagged at LVL2.

  12. Trigger Rate/Threshold Summary Comparisons with TDR value : no pile-up, e.t.c. > Now pretty sure that the numbers in TDR(1J400 e.t.c.) is close to or exactly the “offline” quality jet Et such as Atlfast Jet. > We should start with those values and see how much FTK improves.

  13. Sensitivity Study w/o FTK For signal, MA = 500 GeV,tan=30. For bkg, minPt = 75 dijet. To setup “baseline point” to be compared. > 4 Jet Trigger Default Requirement w/o FTK : - HLT : Jet Et (atlfast) > 90 GeV (~ 20 Hz @ 2*10^{33}) - Higher threshold on 1st and 2nd jets. (200,150) > After this selection, I applied btagging and calculated Ns & Nb. B tagging efficiency : - 50 % for real b quark - 10 % for charm quark - 1% for other jets (mistag) (Randomized tagging) Summing event tagging probability, where each jet has a prob. depending on KFJET (ID), to get acceptances instead of counting the number of events. (just weighting). Because of too low efficiency. So stat. uncertainty is huge in the following numbers.(from next page) -> Need more stat. anyway.

  14. Prelim. of Prelim. Results Selection Variables : (200,150,50,30) & (200,150,90,90) “Do not pay attention absolute values yet”. (Too good significance.) - Trying to understand (But relative comparison should be OK at some level)

  15. Other Backgrounds Overall : Too low numbers compared to previous study (1997). -> under investigation (Stat. is not enough) As btag increased, heavy quark production becomes relevant.

  16. Summary & Plan • Tried to understand LVL1 calo. response • Extracted Et threshold @ 200Hz and 20Hz for J1, J2, J3, J4 trigger table, now have better understanding. • Tried to calculate signal significance with 30fb-1, but seems bkg rate is too low, giving too high significance. - Need to check with more stat. • To make more realistic scenario, - Full simulation for signal events (also some of bkg?). - High luminosity effects have to be considered. - Additional cuts like Mbb mass window. • Also nice to see 3jets trigger as well. • Athena version : change to 11.0.x - Need validation. • Study on the FTK simulation

More Related