1. H/Abb -> 4b’s process & Multi-Et-Threshold Study for 4jet Trigger Kohei Yorita Young-Kee Kim University of Chicago @ the FTK Meeting on July 13 th, 2006

2. 2 4jets w/o btag LVL1 Out 1KHz LVL2 Out 100Hz 4 Jet Trigger Review LVL1 (10us)LVL2 (20ms) Current Menu (w/o FTK) 4J(~60) : 200Hz4J(70) : 100Hz w/ FTK4J(40) : 1KHz4J(40) : 100Hz w/ btag  Current (TDR) Menu : - High threshold of 4J(60) at LVL1 has been determined due to poor LVL2 reduction w/o btagging. Here L2 reduction ~ 2, so 200Hz is necessary at LVL1 output.  With FTK, threshold can be lowered down to 40 from 60, giving 1KHz. * We just assume Max 4J LVL1output is 1KHz, not limited by LVL2 reduction but data transfer and 4J trigger budget. (Total LVL1 rate : ~ 50KHz) So to maximize performance, LVL2 reduction has to be more than a factor of 10 by only btagging w/ FTK !!! LVL1 Out 200 Hz

3. 3 LVL2 Reduction by btagging Since we haven’t had realistic btagging rate and fake rate, Right plot shows LVL2 reduction vs Ru(Rejection against non-b jet) where btagging efficiency is 50% with different Nbtag (1-4). In order to have a factor of 10, We need (1) If 1btag : fake rate < 10 % (2) If 2btag : fake rate < 33 % (3) If 3btag : fake rate < 50 % I guess that (1) can be achievable by FTK ! So again real limit on LVL1 threshold is not from FTK at LVL2 ! In principle by FTK btagging, we can change Pt threshold as low as possible because even if fake rate is high, we can increase N of btag.

4. 4 Update (Single Et Threshold for 4J) M A (GeV ) 150200250300350400500600700800900 No Pt cut Pt > 10 610 177 212 69.5 87.9 31.5 42.1 16.0 21.9 8.66 12.1 5.00 4.30 1.89 1.74 0.81 0.38 0.40 0.19 0.21 0.10 Correct oneShown at last FTK meeting Xsec used was without parton Pt cut ! But MC was generated with Pt > 10 GeV !!! Cross section  BR (pb) Still impressive Improvements !!!

5. 5 So far, only “single Et threshold” has been used even for multijet trigger, but in most physics process (at least this channel : H/Abb->4b’s),  1 st and 2 nd jets are more energetic jets (from H/A)  3 rd and 4 th jets Et spectra are much softer. Questions are,  Keeping LVL1 output rate, How much 4 th (and 3 rd ) jet Et threshold can be lowered by increasing 1 st and 2 nd jet ?  How much it helps signal acceptance ? What’s physics impact ? Multi-Threshold Study

6. 6 MC Samples 851 ev passed 55 ev passed 5 M events Cross sections yt>25 : 0.36 mb yt>20 : 0.83 mb yt>10 : 9.8 mb We did expect to see “higher rate” around Pt > 20 GeV with yt 10, but yt cut 10 gives lower rate than 20 and 25, which dose not make any sense. Need to be understood why this happens. - Still under investigation. Since yt 20 and 25 samples agree very well even in lower Pt region, I used yt>20 as a default for multi-threshold study. (But down to 4 th Pt > 20 !!!) Default is Sherpa 2to2+2to3 with yt>25 sample. But nice to lower yt cut for multi-threshold study.

7. 7 Multi-Threshold Scan Procedure 4 th jet Pt > 30 GeV 1 st jet Pt : ….. 60 70 80 90 100 > As already discussed, interesting region to be compared with single value threshold is ~ 1KHz (Max LVL1 output (4J40)). Case Category (for jet pt order) Case1: j1>j2>j3>j4 : 4 parameters (no physics bias) Case2: j1>j2>j3=j4 : Good for hard 2j + soft 2j Case3: j1>j2=j3>j4 : any physics model ? Case4: j1=j2>j3>j4 : If back-to-back two jets + X ? Case5: j1>j2=j3=j4 : If only 1 st jet is really energetic Case6: j1=j2=j3>j4 : Good for 3jets + X process Case7: j1=j2>j3=j4 : Good for hard 2j + soft 2j Case8: j1=j2=j3=j4 : Single Threshold 4 th jet Pt threshold is set to be 20 GeV or 30 GeV, and 2 nd, 3 rd and 4 th jet Pt are changed up to 100 GeV by 10 GeV step. (see figure. In each range, 2 nd and 3 rd jet Pt are scanned from 30 GeV to 1 st jet Pt.) Then for each case (1-8), the closest point to 1KHz is chosen. And compare Trigger rate and Signal acceptance.

8. 8 Multi-Threshold Scan Results Cut valueTrig RateS(500)Cut valueTrig RateS(500) Default (w/o FTK)70 70 90 Hz6.3 %70 70 90 Hz6.3 % Default (w/FTK)40 40 830 Hz24.2 %40 40 830 Hz24.2 % 4 th Jet Pt > 20 GeV4 th Jet Pt > 30 GeV Case1: j1>j2>j3>j480 70 50 20999 Hz37.3 %90 60 40 30957 Hz33.3 % Case2: j1>j2>j3=j4100 90 20 20954 Hz45.1 %100 50 30 301001 Hz34.6 % Case3: j1>j2=j3>j4100 50 50 20960 Hz37.3 %60 50 50 301015 Hz30.5 % Case4: j1=j2>j3>j480 80 40 201009 Hz41.3 %70 70 40 30938 Hz33.0 % Case5: j1>j2=j3=j4130 20 20 20916 Hz45.9 %100 30 30 301056 Hz34.7 % Case6: j1=j2=j3>j460 60 60 20795 Hz31.5 %50 50 50 301027 Hz30.6 % Case7: j1=j2>j3=j490 90 20 20989 Hz45.3 %70 70 30 301044 Hz34.5 % Case8: j1=j2=j3=j420 20 10.7 KHz54.3 %30 30 2.6 KHz36.5 % Each point was selected when trigger rate became closest to 1KHz in each case. Keeping 1KHz by increasing 1 st (~80 GeV), 2 nd (60-70 GeV), and 3 rd (40-50) jet Pt but by lowering 4 th jet Pt (20, 30 GeV), Signal (M_A = 500 GeV) acceptance increases by a factor of 1.5~2 !!! Numbers in red are just highest 3 in each column.

9. 9 With Other Mass Samples 4 th jet Pt > 20 GeV 4 th : 20 GeV Sig eff(200)Sig eff(300)Sig eff(400)Sig eff(500)Sig eff(900) Default (w/o FTK)0.6 %1.7 %3.7 %6.3 %17.3 % Default (w/FTK)5.0 %11.3 %18.1 %24.2 %39.4 % Case1: 80 70 50 206.4 %17.1 %28.4 %37.3 %55.3 % Case2: 100 90 20 204.9 %17.7 %33.5 %45.1 %63.8 % Case3: 100 50 50 206.0 %16.9 %28.4 %37.3 %55.3 % Case4: 80 80 40 206.1 %17.9 %31.3 %41.3 %59.4 % Case5: 130 20 20 204.9 %17.8 %34.5 %45.9 %64.0 % Case6: 60 60 60 205.2 %13.8 %23.3 %31.5 %50.4 % Case7: 90 90 20 205.2 %18.1 %33.4 %45.3 %63.8 % Case8: 20 20 20 2027.0 %39.8 %48.3 %54.3 %66.0 % > Please note that “FTK w/ single value” already improves signal efficiency by a factor of 2~9 depending on mass. See first 2 lines. > “FTK+Multi-threshold” : Additional factor of 1.2~2 at trigger level. > Case2, 5, 7 look promising, as expected, in high mass range, but not the case for low mass (200,300), because 1 st and 2 nd leading jets are not so hard. Numbers in red are just highest 3 in each column.

10. 10 With Other Mass Samples 4 th jet Pt > 30 GeV 4 th : 30 GeV Sig eff(200)Sig eff(300)Sig eff(400)Sig eff(500)Sig eff(900) Default (w/o FTK)0.6 %1.7 %3.7 %6.3 %17.3 % Default (w/FTK)5.0 %11.3 %18.1 %24.2 %39.4 % Case1: 90 60 40 306.0 %15.6 %25.6 %33.3 %49.6 % Case2: 100 50 30 306.0 %16.2 %26.7 %34.6 %50.7 % Case3: 60 50 50 306.3 %14.7 %23.4 %30.5 %47.0 % Case4: 70 70 40 305.9 %15.1 %25.0 %33.0 %49.5 % Case5: 100 30 30 306.2 %16.5 %26.9 %34.7 %50.7 % Case6: 50 50 50 306.3 %14.7 %23.4 %30.6 %47.1 % Case7: 70 70 30 306.3 %16.2 %26.5 %34.5 %50.6 % Case8: 30 30 30 3011.6 %21.5 %30.0 %36.5 %51.1 % > Even if Pt>30 GeV, “FTK+Multi-threshold” gives additional factor of 1.2~1.5. > Need to look at LVL1 parameterization. > Even if LVL1 param is used, ROI reconstruction efficiency is enough for low Pt jet ? Where are we considering this effect ?? Numbers in red are just highest 3 in each column.

11. 11 Summary & Plan Multi-Threshold with 4 th Pt > 20, 30 GeV shows improvement on signal acceptance by a factor of 1.2~2.0 w.r.t. w/ FTK condition. - So “FTK+Multi-Threshold” seems best way to go. -- FTK bagging @ LVL2 : Good for low Higgs mass. -- Multi-Threshold : Good for high Higgs mass. - But comparisons of w/ and w/o FTK by “single threshold” should be clearly done first in documentaion. Things to do : - So far all study has been done Atlfast Pt base. -- Need to redo by LVL1 Parameterization. - Figure out / validate new Sherpa sample (Erik’s), clarify yt cut 10 issue. - Good to try to measure dijet (H/A) mass. - Final Check with other generator & full sim. - Documentation … -- Being Prepared (just started..not much done yet.) - 4Jet Trigger Rate with multi-threshold discussion - H/Abb physics case w/ and w/o FTK. Now let’s try to finish as quickly as possible !!

12. 12 Optimized Cut Values (single threshold) MAMA w/ FTK (+4btag)w/o FTK (+4btag) 150(40,40,40,40)(70,70,70,70) 200(60,40,40,40)(70,70,70,70) 250(70,40,40,40)(70,70,70,70) 300(80,60,40,40)(70,70,70,70) 350(100,60,40,40)(70,70,70,70) 400(120,80,40,40)(100,70,70,70) 500(160,90,40,40)(140,90,70,70) 600(200,100,40,40)(160,90,70,70) 700(230,130,40,40)(210,120,70,70) 800(280,150,40,40)(230,120,70,70) 900(300,200,40,40)(280,170,70,70) w/ FTK starts from (40,40,40,40) w/o FTK starts from (70,70,70,70)