Progress on the FTK Physics Case (For H/Abb 4b signal) Kohei Yorita Young-Kee Kim University of FTK Meeting on January 26 th, 2006 (1)Brief Sample Descriptions (2)LVL1 Rate & Threshold Estimation (3) “Rough” Significance Estimation (w/o FTK) (4) Summary & Plan Contents

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, where M A = 500 GeV, tan  = 30. (Xsec ~4 pb) > Backgrounds : - Pythia dijet samples (minPt cut = GeV). - Pythia bbbar samples (minPt cut = 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 SHERPA (Erik’s) (old?) PYTHIA Y/pt cut Xsec  (  b) eff *10^4 4j(40GeV ) Rate 10^33 eff*10^4 4j(40GeV ) Rate 10^ e

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

5 J1 : Single Jet L=2x Hz 20 Hz 200 Hz 20 Hz No phase spaceNo 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 L=2x Hz 20 Hz 200 Hz 20 Hz It seems current trigger requirement HLT) 100% prohibits us from working on Jet calib. using Z (->bb) mass peak.

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

8 J4 : 4 Jets Trigger L=2x Hz 20 Hz 200 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 0.2KHz 2 KHz 20 KHz 0.2KHz 2 KHz 20 KHz These two variables correspond between 50 ~ 90% efficiency line w.r.t. trigger rate.

10 All(J1,J2,J3,J4) in one together 200 Hz 20 Hz 200 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)) Using Ptmin=30 GeV dijet sample

11 Other processes: bb/tt productions PYTHIA pt cut (b)(b) Eff*10^4 4j(40GeV) Rate (Hz) at 10^33 bb bb bb bb tt 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 200 2x J2J3J4J TDR Atlfast Et~200~160~ 90~ 55 8x8 Calo Et~160~120~ 55~ J1J2J3J4 TDR Atlfast Et 2x10 33 ) ~ 400 (320) ~350 (250) ~ 170 (130) ~ 110 (90) 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 To setup “baseline point” to be compared. > 4 Jet Trigger Default Requirement w/o FTK : - HLT : Jet Et (atlfast) > 90 GeV (~ 20 2*10^{33}) - Higher threshold on 1 st and 2 nd 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. For signal, M A = 500 GeV, tan  =30. For bkg, minPt = 75 dijet.

14 Prelim. of Prelim. Results Selection Variables : (200,150,50,30) & (200,150,90,90) L= 30 fb -1eff SS(500)BS/BS/sqrt(B) (200,100,50,30)1.7e e+83.7e-5(0.9) + 1st bjet0.9e e+77.9e-4(3.0) + 2nd bjet4.1e e+51.3e-2(8.4) + 3rd bjet1.5e (18.1) + 4th bjet0.4e (27) L= 30 fb -1eff SS(500)BS/BS/sqrt(B) (200,100,90,90)1.9e e+73.8e-5(0.3) + 1st bjet9.5e e+68.4e-4(1.0) + 2nd bjet4.4e e-3(1.7) + 3rd bjet1.6e (6) + 4th bjet4.8e (10) “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 L= 30 fb -1dijetbbtt (200,100,50,30)5.9e+82.0e+65.7e+5 + 1st bjet1.4e+74.9e nd bjet3.7e rd bjet th bjet L= 30 fb -1dijetbbtt (200,100,90,90)6.4e+72.8e st bjet1.4e nd bjet rd bjet th bjet37161 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 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