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Generation of samples for VBF H0-->ZZ*-->bbll

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Presentation on theme: "Generation of samples for VBF H0-->ZZ*-->bbll"— Presentation transcript:

1 Generation of samples for VBF H0-->ZZ*-->bbll
Signal : mH = 130 : Xsec = 1.6 fb, Pythia, > 200K events. mH = 140 : Xsec = 2.6 fb, Pythia, 200K events. mH = 150 : Xsec = 2.9 fb, Pythia, 200K events. Backgrounds : bb : Xsec = fb, MCatNLO+JIMMY, > 400K events tt : Xsec = fb, MCatNLO+JIMMY, >700K events Zbb : Xsec(qq-->Zbb) = fb, AcerMC + Pythia , ~ 300K events Xsec(gg-->Zbb) = fb, AcerMC + Pythia , 450K events ZZ : Xsec = MCatNLO + JIMMY : in progress Z/gamma : Xsec = MCatNLO + JIMMY : in progress files generated but problem to produce ATLFAST CBNT.

2 Signal distributions for mH=130 at generation level
High mass of VBF jet-system Wide separated jets coming from VBF

3 Signal eta distributions (2)
Central leptons Central B jets

4 Signal mass distributions (3)
Compatible with virtual Z Mass window

5 Signal Pt distributions (4)

6 bb background generated with MC@NLO
Too low statistics ( % of total). 2 ideas to improve that : 1/ ~ 84% of leptons come from b hadrons. Idea = to force the semileptonic decays of the b hadrons.  How to force the decays in HERWIG ? Up to now, not found. 2/ Cut on the hard process Pt : Is it still ok with a 2 --> 3 process ?  Pt distribution shows no difference before and after cut.

7 Event selection Precuts : 2 b jets, |η| < 2.7, Pt > 5 GeV/c
2 leptons, |η| < 2.7, Pt > 5 GeV/c The lepton pair with the highest Pt The b-jet pair with the reconstructed mass the closest to Z mass. Dilepton system mass compatible with a virtual Z mass : mll є [10;70] Trigger : electrons : At least one Pt > 25 GeV/c or 2 Pt > 15 GeV/c muons : At least one Pt > 20 GeV/c or 2 Pt > 10 GeV/c VBF jets : 2 jets, η1.η2 < 0, |Δη| > 4, the pair with the highest mass. mjj > 500 GeV/c2 Possible Additionnal cuts : Ptmiss < C_ Ptmiss : against tt background. mll, Ptb, ΔRll and ΔRbb.

8 Efficiencies (mH = 130 GeV/c2)
Cuts Nevents Efficiency (%) Generation 50000 - Precuts 3763 7.5 Trigger 1965 52.2 Tagging jets 1009 51.3 Leptons and b jets between VBF jets 696 69.0 bb mass window on Z mass 236 33.9 HZZ*bbll 0.5

9 Distributions (mH = 130 GeV/c2) (1/2)
Cut on Ptmiss


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