Investigations into the physics channels PPbbHH

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Investigations into the physics channels
PP?bbH(H???) Dan Holmes, student at Bristol.
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My Channels PP?bbH, H ???
b
H
??
gg
2 Main sorts of diag gg ?bbH(??) and qq ?bbH(??)
b
b
qq
H
??
(or)
...contribution from gluon fusion about 1000
bigger than qq.
b
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MH and s

• Used Spiras HQQ(1.1) and HDECAY(3.0) with
  NLO/LO K1.6.
• For all cases (SM, MSSM), v. small signal order
  0.09 to 0.15 fB passing basic CMS acceptance.
• Only regions worth looking at are
• SM MH125GeV
• MSSM (H) MH128, MA108, tanß30
• MSSM (h) MH127, MA144, tanß30

acceptance require PT ?1gt40, PT?2gt25, PT
jet(s)gt20 GeV, bTaggt0,1 ?s within fiducial
regions.
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Backgrounds
first two backgrounds used PYTHIA 6.205
(1) PP???radiation/PU of a jet(s)
jet
jet
etc...
(2) PP?jet(s) radiation/faking/PU of ??

• order of 100 fB passing acceptance cuts (1000x
  signal!)
• can be kept to ltltfB by simple b-tagging cuts.

?s, etc...
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Optimising vs Pythia back
Ran samples through CMSJET, added PU. ...using
cuts on PT of ?s, jet(s), PT1-PT2, MH, PTH,
b-tagging efficiency as well as topological cuts
eta,phi,deltaEta,deltaPhi of ?s, jet(s), this was
the best i could do
..so after looking at PYTHIA background,
indication that there might be some chance of
seeing 1-tag channels... ..but...
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MADGRAPH backgrounds
Made some more background (LO) processes using
MADGRAPH
(1)Irreducible background processes where hard
scattering really makes bb??. About 0.5 fB pass
basic acceptance. (2) Light Jet background
where the hard scattering makes us, ds etc.
which then look like b jets. About 28 fB pass
basic acceptance.
acceptance (as before) require 2 ?, 1 jet with
btag
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Problem new background topology

• New (MADGRAPH) backgrounds compared to previous
  (PYTHIA) one
• Smaller Cross sections (0.5 and 28 fB), compared
  to 100 fB.
• Much flatter Pt distribution for both gammas and
  jet.

PYTHIA PT ?1
MADGRAPH bb ? ? PT ?1
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more ? pics...
PYTHIA PT ?2
MADGRAPH bb PT ?2
PYTHIA ? opening angle
MADGRAPH bb ? opening angle
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jet pics
MADGRAPH bb PT jet1
PYTHIA PT jet1
MADGRAPH bb PT jet2
PYTHIA PT jet2
nb for these plots, only 1 jet required
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..which all means...

• I cant find any regions of high signal
  significance anymore.. (actually can only just
  about beat the bb?? back..)
• I also looked at the COMPHEP bb?? and light
  jet?? samples made by Misha Dubinin. They
  looked exactly the same as the MADGRAPH ones, but
  i have less stats past my cuts.. plots for
  anyone interested
• Did do a comparison of the simple di-? back
  produced with PYTHIA and MADGRAPH ..all matches
  ok.. plots for anyone interested
• ALPGEN PhJet package now should work with Les
  Houches format interface?? ..recent bug fix..

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in summary...

• channel PP?bbH(?)
• signal of order 0.09 to 0.15fB
• backgrounds of order 100, (28 0.5) fB
• Simulated using CMSJET PU.
• Maybe there is some cut combination that will
  give you a signal significant region but i have
  not found it..

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..table for sasha PYT-MAD, ??jetjet