Erik Brubaker U of Chicago LVL1 rates & Hhh4b Erik Brubaker U of Chicago

Outline Almost-final word on LVL1 jet rates. Understanding cross-section for Hhh4b process. Talk descoped due to UC Tier2 going down last night… September 7, 2006 FTK Meeting

Jet rates from Sherpa Sample LVL1 4jet(40) rate @1033 [Hz] LVL2 4tag rate @1033 [10-3 Hz] 2->2+3 @ 10 38.5 ± 4.4 0.2 ± 0.2 2->2+3 @ 25 47.5 ± 1.0 3.0 ± 2.9 2->2+3 @ 50 50.7 ± 0.3 0.8 ± 0.4 2->2+3+4 @ 10 42.0 ± 22.7 0.0 ± 0.0 2->2+3+4 @ 25 65.9 ± 3.8 2->2+3+4 @ 50 56.2 ± 0.6 0.4 ± 0.2 2->3 @ 10 58.4 ± 2.3 0.1 ± 0.1 2->3 @ 25 58.7 ± 0.4 0.3 ± 0.0 2->3 @ 50 66.7 ± 0.2 0.8 ± 0.1 2->3+4 @ 10 75.2 ± 32.5 2->3+4 @ 25 82.8 ± 4.0 18.7 ± 18.6 2->3+4 @ 50 73.7 ± 0.6 2.3 ± 1.3 Check different ME combinations, kT,cut values to balance stats/resources, and to estimate systematics. LVL1 rates scatter in 40-80 Hz. “LVL2” rates require 4 tags, have units of mHz! Not too interesting as is. September 7, 2006 FTK Meeting

Cross-check: jet rates from Alpgen Samples from Ambreesh/SUSY group. ALPGEN light jet samples only. LVL1 rates slightly underestimated Total rate lower than, but on the order of, Sherpa results. Caveat: 4- and 5-jet samples ntupled with 0.7-cone jets—inconsistent with parametrizations… Sample LVL1 4jet(40) rate @1033 [Hz] 3 jet 8.79 ± 0.03 4 jet 15.71 ± 0.01 5 jet (incl) 9.64 ± 0.02 Total 34.14 ± 0.04 September 7, 2006 FTK Meeting

Cross-check: jet rates from Pythia Check against Pythia dijets Generic QCD incl heavy flavor Caveat: Default Pythia settings for UE etc. have been unstable… Sample LVL1 4jet(40) rate @1033 [Hz] pT > 50 GeV 95.0 ± 11.9 So… 1. Consistency among models? 2. All are consistently lower than TDR rate: 200 Hz for 4j@90 GeV, where 90~=60 in our calibration… September 7, 2006 FTK Meeting

Systematics on LVL1 jet rates Variations in ycut, ME configurations in Sherpa RMS of the 12 sample results, weighted by reported stat unc.: 12% Differences among generators Alpgen lower, Pythia higher with caveats: 30% for now Additional possible factors—need to check explicitly? PDFs UE/MPI Parametrizations RMS=13.1 RMS=7.5 September 7, 2006 FTK Meeting

LVL1 rates conclusion Need to finish checking effect of UE/MPI in Sherpa, also different pythia settings (MWT2 died on me last night). Run this by ATLAS trigger gurus. Any similar recent studies? Difference w.r.t. TDR understood? Recommendation for FTK studies: Use Sherpa sample with best combination of statistics, ME configuration, and kT,cut for your proposed thresholds. (Best to try more than one.) Use my machinery to calculate rates for a range of thresholds. Assign 35% uncertainty on absolute rate. http://hep.uchicago.edu/~brubaker/ftk September 7, 2006 FTK Meeting

Example LVL1 rate scan Require 4 jets: 1st & 2nd at cut on x-axis; 3rd & 4th at cut in legend. 4th jet cut drives rate— not surprising September 7, 2006 FTK Meeting

Hhhbbbb sigma*BR I had a problem with low s*BR (2 fb) reported by pythia for Hhhbbbb w/ mh=130, mH=300. What MSSM model was pythia assuming? Turns out Hhh is large only for lowish tanb, and for 2mh<mH<2mt. To find operating points: Use mhmax scenario to stay away from LEP direct search limits. For a given tanb, scan mA to maximize s(ggH) x BR(Hhh) x BR(hbb) x BR(hbb). tanb 2.5 2.75 3.0 3.25 3.5 4.0 4.5 5.0 mA 360 260 230 240 250 s*BR [fb] 233 1019 1060 818 637 398 168 September 7, 2006 FTK Meeting

Additional slides

Physics Case (Details) Statement #1 FTK vs TDR menus, i.e. no tracking at LVL2—ignore timing. Statement #2 FTK vs nominal LVL2, incl. tracking. Need: FTK allows b-jet (t) ID w/ eb, ec, eq, et. Correlation w/ offline? Depends on environment LVL1 trigger rate, driven by multijet evts, estimated using modern generator + parametrization of full ATLAS LVL1 simulation. Fix LVL2 output rate. Limit LVL1 output rate to sth reasonable. Optimize LVL1 cuts & LVL2 tagging reqs, maximizing signal acceptance/ significance. Same as stmt #1, but add trigger timing into the eqs. Hard to estimate, large uncertainties. But more realistic, stronger case. September 7, 2006 FTK Meeting

CKKW vs MLM CKKW: 2 parts MLM: matching prescription ALPGEN SHERPA Reweight ME to reproduce PS behavior for soft emissions. Reject showers that overlap higher-order ME. Boundary is kT,cut or ycut  kT,cut2/s. MLM: matching prescription Cluster partons after shower, compare to ME partons. Require each ME parton to match a unique “jet”, else reject event. ALPGEN SHERPA 4p ME 3p ME CKKW MLM September 7, 2006 FTK Meeting