Status Report: H ZZ (*) mm qq(bb) via VBF
description
Transcript of Status Report: H ZZ (*) mm qq(bb) via VBF
Marco De Mattia, Tommaso Dorigo, Mia Tosi, Pietro Vischia
Universita’ degli Studi di Padova & INFN
October 18th, 2010
Status Report:Status Report:HHZZZZ(*)(*)qq(bb) via VBFqq(bb) via VBF
• studies @7TeV• pre-selection• tag-jets selection BDT• high-mass Higgs selection
• leptonic Z selection• hadronic Z selection b-tagging
• conclusion&plans
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analysis strategy
high-mass Higgs both Zs are• on-shell• boosted
look for• a Z [ kinematics]• a Zbbbar [b-tag+jet kinematics]
high-mass Higgs both Zs are• on-shell• boosted
look for• a Z [ kinematics]• a Zbbbar [b-tag+jet kinematics]
low-mass Higgsone Z is on-shell and @restwhile, the other is off-shell
look for• an on-shell Z [ kinematics]• an off-shell Zbbbar [b-tag]
low-mass Higgsone Z is on-shell and @restwhile, the other is off-shell
look for• an on-shell Z [ kinematics]• an off-shell Zbbbar [b-tag]
0-order pre-selection[physics objects and topology]
0-order pre-selection[physics objects and topology]
tag-jets[signal kinematics by BDT]
tag-jets[signal kinematics by BDT]
jetZ1
jetZ2
jetT2
jetT1
longitudinal view
muon1
muon2
transversl view
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samples Spring10• produced in CMSSW_3_5_6• generated @s=7TeV w/o pile-up• fully simulated w/ IDEAL geometry• ntplized
signal datasetNLO (fb)
H (ZZqq)
NLO (fb)
H (ZZbb+eebb)
mH=130GeV/c2
~2.16 ~0.93
mH=150GeV/c2
~3.86 ~1.67
mH=500GeV/c2
~1.07 ~0.46
signal samples
•VBF [PYTHIA6]130,150,500 GeV/c2
+200,300 GeV/c2 [private]
number of expected eventsin Lint=1fb-1 is ~0 !!!
[integrated luminosity in 2010+2011]
number of expected eventsin Lint=1fb-1 is ~0 !!!
[integrated luminosity in 2010+2011]
•Z+jets - SHERPA [M10to50 + M50to10000] [MADGRAPH one has cuts @GEN]•Zbb - MADGRAPH VQQ•ttbar - MADGRAPH TTjets•VV - PYTHIA6 ZZincl - PYTHIA6 WZincl - MADGRAPH VVJets
bkg samples (official)
• only limits on the Higgs mass• only limits on the Higgs mass
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pre-selections
@ 0-order ask for
at least 2 muons w/• pT 15 (10) GeV/c• q1 q2 < 0• m> 12.GeV/c2
at least 4 (PF)jets w/• pT 15 (30) GeV/c in the barrel (forward) region
sample # of eventsefficiency
(%)
HZZqqll (130)
12.3k/90.1k 13.65±0.11
HZZqqll (150)
16.6k/91.8k 18.10±0.13
HZZqqll (500)
23k/84k 27.37±0.15
Z+jets 12k/2.1M 0.01±0.01
VQQ+jets 37k/2.9M 1.25±0.01
TTbar+jets 31k/1.4M 2.23±0.01
WZ 869/118k 0.74±0.02
ZZ 12k/140k 1.59±0.03
all backgroun
ds93k/6.6M 1.41±0.01
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tag-jets selection: BDT
known the right combination [jet-parton matching w/in R0.5]now, it is possible to
exploit the kinematics and choose the tag-jets pair applying a multivariate method [BDT]
trained to distinguish between two different categories:
• signal-like events: all matched jets to tag-partons
• background-like events: wrong [random] choice
|max| jj1x2 mjj
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tag-jets selection: BDT
known the right combination [jet-parton matching w/in R0.5]now, it is possible to
exploit the kinematics and choose the tag-jets pair applying a multivariate method [BDT]
trained to distinguish between two different categories:
• signal-like events: all matched jets to tag-partons
• background-like events: wrong [random] choice
BDT output@70%
of signal efficiency
mH=130GeV/c2 mH=500GeV/c2
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tag-jets selection: BDT cut [mH=500GeV/c2]
sample# of
eventsefficiency
(%)
HZZqqll (500)
5.4k/23k(84k)
77.75± 0.75(4.99±0.
75)
Z+jets192/12k(2.1M)
0.01±0.01(0.01±0.01)
VQQ+jets797/37k(2.9M)
2.17±0.08(0.03±0.01)
TTbar+jets1074/31k
(1.4M)3.46±0.10
(0.08±0.01)
WZ21/869(118k)
2.42±0.52(0.02±0.01)
ZZ33/2k(140k)
1.48±0.26(0.01±0.01)
all backgroun
ds
2117/83k(6.8M)
2.54±0.05(0.03±0.01)
signal efficiency (%)
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Z candidates selection
muon ID - identified as both Global and Tracker Muon - 2/ndof < 10 [global fit] - # tracker Hits > 10 - # muon-detector Hits > 0 - dxy < 0.2 cm
Zselection - opposite charge muons - pT(1) > 15 GeV/c - pT(2) > 10 GeV/c - || < 2.4 - mclosest to mZ - m≥ 12 GeV/c2
L=30fb-1 L=30fb-1
L=30fb-1 L=30fb-1
L=30fb-1
after pre-selection+BDT+2b-tags
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Z selection: mass window optimization
after (2)b-tag cut,no sufficient statistics for optimizing the Z mass window
scale distributions before this cut to statistics after it
after (2)b-tag cut,no sufficient statistics for optimizing the Z mass window
scale distributions before this cut to statistics after it
L=30fb-1
after pre-selection+BDT
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Z selection: mass window optimization
q-value:= S/√B
1.70
signal efficiency (%)
81
background suppression
(%)77
[83;99][83;99]
L=30fb-1
scaled to after b-tag cut
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Z selection: mass window optimization
sample# of
eventsefficiency
(%)
HZZqqll (500)
4319/5375(84k)
80.35± 0.54(5.16±0.
76)
Z+jets143/192(2.1M)
74.48±3.15(0.01±0.01)
VQQ+jets587/797(2.9M)
73.65±1.56(0.02±0.01)
TTbar+jets79/1074(1.4M)
7.36±0.80(0.01±0.01)
WZ17/21(118k)
80.95±8.57(0.01±0.01)
ZZ21/33(140k)
63.64±8.38(0.01±0.01)
all backgroun
ds
847/2.1k(6.8M)
40.01±1.06(0.01±0.01)
L=30fb-1
scaled to after b-tag cut
[83;99][83;99]
≥ Nb-tag
events w/
#b-quarks ≥ 1
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b-tagging
CMS develops several b-tagging algorithms….. but, WHICH ONE TO CHOOSE ?!?CMS develops several b-tagging algorithms….. but, WHICH ONE TO CHOOSE ?!?
considering as discriminator cut [for each algo]
the value|b-tagging 60% [on signal],
look@ different performance in terms of S/N, paying attention on the b-jet multiplicity
≥ Nb-tag
CombinedSecondary
Vertex
all events
≥ Nb-tag
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b-tagging efficiency
≥1 b-tags ≥2 b-tags
sample# of
eventsefficiency
(%)# of
eventsefficiency
(%)
HZZqqll (500)
860/4319(84k)
19.91±0.61
(1.03±0.03)
276/4319(84k)
6.39±0.37(0.33±0.0
2)
Z+jets5/143(2.1M)
3.50±1.54(0.01±0.0
1)
1/143(2.1M)
0.69±0.69(0.01±0.0
1)
VQQ+jets139/587(2.9M)
23.68±1.76
(0.01±0.01)
9/587(2.9M)
1.53±0.51(0.01±0.0
1)
TTbar+jets43/79(1.4M)
54.43±5.60
(0.01±0.01)
7/79(1.4M)
8.86±3.20(0.01±0.0
1)
WZ1/17
(118k)
5.88±5.71(0.01±0.0
1)
0/17(118k)
0.00±0.01(0.00±0.0
1)
ZZ3/21
(140k)
14.29±7.64
(0.01±0.01)
0/21(140k)
0.00±0.01(0.00±0.0
1)
all backgroun
ds
191/847(6.8M)
22.55±1.46
(0.01±0.01)
17/847(6.8M)
2.01±0.48(0.01±0.0
1)
L=30fb-1
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Zqq selection
jet ID - R(j,Z) ≥ 0.5 - pT(j1) ≥ 50 GeV/c - pT(j2) ≥ 25 GeV/c
Zqq selection
CENHIGHPT VBF BTAG ZKIN ZZKIN
highest-pT jetsmin
(j1,j2)max
(j1j2, 12)w/ ||≤2.5between tag-jets
b-tagged
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Zqq mass reconstruction
L=30fb-1
CENHIGHPTVBF
BTAG
ZKIN
ZZKIN
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4-bodies mass reconstruction
L=30fb-1
CENHIGHPTVBF
BTAG
ZKIN
ZZKIN
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4-bodies mass reconstruction
L=30fb-1
requesting
(2)b-tagrequesting
(2)b-tag
CENHIGHPTVBF
BTAG
ZKIN
ZZKIN
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addendum
the search ofa high-mass Higgs boson into ZZ*in its semi-leptonic final state w/ spass through
an almost standard Z-> extraction looking @ events
• w/ high multiplicity jets [>=4]• w/ b-tagged jets -> tracker ;)• w/o MET -> commissioning PAS [JINST]
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BACKUP
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ntuplizer
produce light-ntuplew/ the most complete set of information• event and trigger• MCTruth• Muons• Jets [different clustering algorithms (AK,IC)] both Calo and PF• Electrons• MET• Vertices
•event and trigger•genPartciles
•GenJets•GenMet•CaloJets•PFJets
•globalMuons•CaloMet
•GfsElectron•PrimaryVertex
simpleNtple
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tag-jets selection: BDT cut [mH=130GeV/c2]
sample# of
eventsefficiency
(%)
HZZqqll (130)
/()
±(±)
Z+jets/()
±(±)
VQQ+jets/()
±(±)
TTbar+jets/()
±(±)
WZ/()
±(±)
ZZ/()
±(±)