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MSSM Higgs (H/Abb 4b-quarks) For FTK Physics Case (First Look). Kohei Yorita University of Chicago FTK meeting on 12/15, 2005. Process. For large values of M A/H and tan , this channel strongly enhanced. BR() : ~ 10% BR(bb) : ~ 90%. The main difficulty is QCD bkg.
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MSSM Higgs (H/Abb 4b-quarks)ForFTK Physics Case(First Look) Kohei Yorita University of Chicago FTK meeting on 12/15, 2005
Process For large values of MA/H and tan , this channel strongly enhanced. BR() : ~ 10% BR(bb) : ~ 90% The main difficulty is QCD bkg. • Particular interests • Extend the parameter space ? • BR measurements, if feasible.
A Brief Summary of TDR In TDR (& PHYS-No-104,1997), this study performed in 2 steps. • W/o trigger : No Acceptance losses at the trigger level • - Idealistic trigger condition, determine optimum physics coverage. - Here is a set of optimized Pt thresholds used : (2) With LVL1/LVL2 thresholds (as of 199x) - More realistic scenario. - The Trigger Menu used for comparisons was (1J180,3J75,4J55). New (?) one is (1J400,3J165,4J110) Significantly changed since then !
Conclusions of TDR 5 sigma contour : > The results were fairly negative. (>5 years ago) > Numbers w/ trigger will be much worse if current LVL1 threshold used. > Property study will still need this channel. > We should try as best as we can…
Signal (H/Abb) Events Generation(with ATLFAST) A set of parameters to generate (PYTHIA): - tan = 30 fixed for all samples. - MA = 200, 300, 500, 700, 900 GeV - H/A : Set force decay into bb (4b final state) * ATLFAST v10.0.1 and v11.0.2 for comparisons. (50K events each with v10, 10K events each with v11) - Setup Athena environment. - Generate events. - Make CBNT Outputs (AOD as well). - Develop Analysis Tool. - e.t.c. e.t.c. There are still many things I do not yet understand, but yes, this is a good practice for me !
Cross Section Xsec reported by Pythia was an order of magnitude lower than TDR. TDR value (I guess) includes the higher-order effect calculated by so called “HIGLUE, HQQ, HDECAY” programs (hep-ph/9510347). @500 GeV && tan = 30 (H/Abb bb) ~ 0.3 pb (H/Abb bbbb) ~ 3 pb c.f. TDR value 3.5 pb (PYTHIA ~ a few hundred fb…) First, I tried to reproduce results of TDR (i.e. signal acceptance and estimate its rate func on lum), But, things were not easy…. Need your help! next…
Number of Jets (v10 vs v11) Generation code I used are exactly the same for both. What’s happening ? (Something was changed ? Or my bug?)
“JETB” Pt Distributions (AtlfastB) Before any cuts except njet>=4 • 2 issues here : • Higher in v11 • @150 GeV, • Gap in v11. • ISR/FSR activity • is different ??? 1st jet Pt 2nd jet Pt 3rd jet Pt 4th jet Pt
“JET” Pt Distributions Looks smooth @ Pt=150 GeV. But still much different b/w v10.0.1 & v11.0.2 1st jet Pt 2nd jet Pt 3rd jet Pt 4th jet Pt
About Pt=150 GeV, JETB vs JETMaybe you could tell me the difference.. v10.0.1 150 GeV Zoom JETB PT JET PT v11.0.2 Zoom Looks good
KFJETB Variable (particle ID with AtlfastB) v10.0.1 Assume correction factor for jets in AtlffastB based on this ID. There are too much tau’s in v10, V11 seems to be OK. v11.0.2
Anyway, nice to look at H/A jj Mass Distributions
THINGS TO DO • Lots of things have to be done … (Now just at a start point) • Need many debugging, plan to solve one by one. More Detailed/Careful Studies ! • Apply Erik’s L1 jet Parameterization. • Background Study using Erik’s SHERPA samples. • More “realistic” Comparisons to ATLAS baseline result. • Estimate Observation Significance (func of int. Lum.), Any Improvements? (lower tan ?) Plan to finish up all above within a (few) month !! ?