gian luca pinna angioni
TRANSCRIPT
Multi-boson production measurements with the CMS detector
Gian Luca Pinna Angioni
4/8/15 1
Physic motivation • Interesting channels: ZZ,W±W±+jets, ZW, WVγ, W+W- ,ecc. • Studies on boson fermion couplings. • Test of electroweak sector of SM.
– Sensitive to the self-interaction between gauge bosons via triple/quadric gauge couplings (TGC,QGC).
– Fundamental to establish if this Higgs boson really can preserve unitarity in the VV scattering amplitude at all energies.
– QCD process are dominant to EW !
• Sensitive to anomalous triple/quadric couplings (aTGC,aQGC) – Analyzable through effective field theory
• Important background to Higgs and beyond-SM searches
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2
ZZ(*)è2l2l’ (8 TeV) Selection: • Two opposite-sign same-flavor lepton
pairs. • l = e,μ l’=e,μ,τ • τ reconstructed in both lepton and
hadron decay
(GeV)lll''l''m200 400 600 800 1000
Even
ts /
25 G
eV
0
20
40
60
80 Data
ZZ
WZ/Z + jets
-1 = 8 TeV, L = 19.6 fbsCMS
(GeV)ττllm200 400 600 800 1000
Even
ts /
25 G
eV
0
5
10
15
Data
ZZ
WZ/Z + jets
-1 = 8 TeV, L = 19.6 fbsCMS
Background: • Z+fake, ZW+fake, WWZ,tt + jets. • Low in e,μ channels
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ZZ(*)è2l2l’ (8 TeV)
L [fb-1] Experimental σ [pb] Theory σ [pb]
19.6 7.7-0.5+0.5(stat)-0.4
+0.5(syst)±0.4(theo)±0.2(lumi) 7.7±0.6
Cross section: Fiducial region: 60 GeV<mZ<120 GeV • Measured separately in each final state
and then combined through likelihood fit on number of events.
• Differential in mZZ, ZZpT, Z1pT, l1pT
Reference: arXiv:1406.0113v2
(GeV)ZZm100 200 300 400 500 600 700 800
) (1/
GeV
)ZZ
/d(m
fidσ
d
fidσ
1/
0
0.2
0.4
0.6
0.8
1Unfolded dataTotal uncertainty
ZZMCFM NLO
CMS -1 = 8 TeV, L = 19.6 fbs
Unfolded dataTotal uncertainty
ZZMCFM NLO
Dat
a/M
C0
1
2
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WVγ (8TeV) V=W,Z Selections • A γ plus a W in leptonic final state and a
V in hadronic final state. • Single tight lepton • Emiss>35GeV • MT
W>30GeV • ET
γ>35GeV |ηγ|<1.44 Background: Wγ+jets,W+jets
Cross Section: No excess above background predictions. • Upper limit 311 fb by profile likelihood
at 95% confidence level. • ~3.4 times SM prediction 91.6±21.7 fb • Expected limit of 403 fb
20 40 60 80 100 120 140
Even
ts/ 1
0 G
eV
10
20
30
40
50
60
= 8 TeVs-1 dt = 19.3 fbL ∫CMS preliminary
bkgγ →jets top
+JetsγZ γWV
Muon Data
MC Uncertainty
+jetsγW
pf MET (GeV)50 100 150
Rat
io D
ata/
MC
1
2
4/8/15 5
Reference: arXiv:1404.4619
ZWèlllν (8 TeV) Selection: • Fully leptonic final states
(eee,eeμ,eμμ,μμμ). • Lepton + ET
miss forming W. Background: • Z+fake (jet,γ) • Irreducible ZZ L [fb-1] Experimental σ [pb] Theory
σ [pb]
19.6 24.61±0.76(stat)±1.13(exp)±1.08(lum)
21.91+1.17
-0.88
Reference: CMS-PAS-SMP-12-006
Cross section: • Fiducial region:
71<MZ<111GeV
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Discovery future projection (Run2)
3σ 5σ
SM EW scattering
75 fb-1 185 fb-1
W+W+,W-W- and VBS in ll+jets Process: W+W+,W-W- Selection: Two high pT leptons. Two jets ET>30 GeV, mjj>500GeV and large rapidity separation Background: DY,WZ,tt, fake Cross section: Fiducial region: , mjj>300, |Δηjj|>2.5,s pT
l>10, |ηl|<2.5, pT
jet>20 GeV, |ηjet|<5.
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(GeV)jjm500 1000 1500 2000
Even
ts /
bin
0
5
10
Datajj±W± W
Other Bkgs. Nonprompt WZ
CMS (8 TeV)-119.4 fb
L [fb-1] Experimental σ [fb] Theory σ [fb]
19.6 4.0+2.4-2.0(stat)+1.1
-1.0(syst) 5.8±1.2
Obs(exp) significance for VBS = 1.9(3.0) σ
Reference: arXiv:1410.6315
Multi boson measurements
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Anomalous coupling • Possibility to test BSM physic adding new triple and quadruple terms/
operators with different dimension to the SM Lagrangian. (aTGC,aQGC) • This new terms are introduced using an effective field theory. • Expected variation in both yield and shape distributions. • Anomalous coupling tested in almost every channel. • Limits set on this operators show no deviations from the SM
50 100 150 200 250 300 350 400 450
Even
ts /
42 G
eV
-210
-110
1
10
210
310
410 = 8 TeVs-1 dt = 19.3 fbL ∫CMS
γ →jets
+jetsγZ
top quark
+jetsγW
γWV
Muon dataMC uncertainty
-2 = 50 TeV2Λ / W0SM + a
Muon dataMC uncertainty
-2 = 50 TeV2Λ / W0SM + a
(GeV)TPhoton E100 200 300 400
Dat
a/M
C
123
z5f
-0.01 0 0.01
γ 5f
-0.01
0
0.01 Best fit68% CL
95% CL
1D 95% CL
-1 = 8 TeV, L = 19.6 fbsCMS
4/9/15 9
ZZ example WVγ example
Conclusion
• All possible multi-boson measurements have been done at CMS. – cross-sections measured: no significant deviations
from the SM – limits set on aTGCs and aQGCs: show no deviations
from the SM • This measurements are the one of the most
important measure for the next run at LHC. – Good prospective for 300 and 3000 fb-1
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Backup Slides
4/8/15 11
Analysis common features
Selection common features: Prompt leptons in all analysis. • Requested isolated leptons in a cone ΔR=√(Δη)2 +(ΔΦ)2 around
leptons. – Values and features depend on the analysis
• The measured energy in the cone is corrected for the contribution from pile-up events.
• Leptons compatible with primary vertex (highest Σp2T vertex)
• Fake leptons background measured with a data driven method.
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W+W-èlνlν (8TeV) Selection: • Opposite-sign high pT leptons. • High missing energy. • Small high pT jets numbers. Background: W+jets, tt,tW, WZ,ZZ Cross section: Cross section measured separatelly in 4 category (flavor, jet numbers) and combined trough likelihood fit.
Even
ts /
(5 G
eV)
0
200
400
600
800
1000 DataWWHiggs
WZ/ZZ/VVVTopDYW+jets
CMS Preliminary (8 TeV)-119.4 fb
+µ-/e-µ+/e-µ+µ/-e+e0-jet
(GeV)lT,max
p20 40 60 80 100 120 140 160 180 200
MC/
data
0.51
1.5
L [fb-1] Experimental σ [pb] Theory σ [pb]
19.4 60.1±0.9(stat)±3.2(exp)±3.1(th)±1.6(lum) 59.8+1.3-1.1 4/8/15 13
W+W-èlνlν (8TeV) Selection: • Opposite-sign high pT leptons. • High missing energy. • Small high pT jets numbers. Background: W+jets, tt,tW, WZ,ZZ Cross section: Cross section measured separatelly in 4 category (flavor, jet numbers) and combined trough likelihood fit.
L [fb-1] Experimental σ [pb] Theory σ [pb]
19.4 60.1±0.9(stat)±3.2(exp)±3.1(th)±1.6(lum) 59.8+1.3-1.1 4/8/15 14
(GeV)llm20 40 60 80 100 120 140 160 180 200
ll(W
W +
0 je
ts)/d
mσ
dσ1
-310
-210
Data Madgraph MC@NLO Powheg
CMS Preliminary (8 TeV)-119.4 fb
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσMadgraph+Pythia normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσMC@NLO+Herwig normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσPowheg+Pythia normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
ll(W
W +
0 je
ts)/d
mσ
dσ1
-310
-210
Data Madgraph MC@NLO Powheg
CMS Preliminary (8 TeV)-119.4 fb
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσMadgraph+Pythia normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσMC@NLO+Herwig normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσPowheg+Pythia normalized to
Reference: CMS-PAS-SMP-14-016
W+W-èlνlν (8TeV) Fiducials region Fiducial region cross section
Fiducial region defined by a jet veto |ηjet|<4.7 and different pT threshold categories.
(GeV)llm20 40 60 80 100 120 140 160 180 200
ll(W
W +
0 je
ts)/d
mσ
dσ1
-310
-210
Data Madgraph MC@NLO Powheg
CMS Preliminary (8 TeV)-119.4 fb
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσMadgraph+Pythia normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a0.5
1
1.5
NNLOσMC@NLO+Herwig normalized to
(GeV)llm20 40 60 80 100 120 140 160 180 200
Theo
ry /
Dat
a
0.5
1
1.5
NNLOσPowheg+Pythia normalized to
Fiducial region cross section 2 Fiducial region defined by a jet veto |ηjet|<4.7 and different pT threshold categories and pT
l >20 GeV.
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WW/WZ+jets diagrams
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ZZ Anomalous coupling • Anomalous tri-linear couplings ZZZ ZZγ introduced with an effective
Lagrangian. • Parameterized by two CP-violating (f4
V) and two CP-conserving (f5V)
complex parameter. V=Z,gamma • One-dimensional fits for each parameter performed to obtain 95% CL:
(GeV)lll''l''m200 400 600 800 1000 1200
(1/G
eV)
lll''l''
dN/d
m
-310
-210
-110
1DataZZWZ/Z + jets
-1 = 8 TeV, L = 19.6 fbsCMS
= 0.015Z4f = 0Z
4f
z5f
-0.01 0 0.01
γ 5f
-0.01
0
0.01 Best fit68% CL
95% CL
1D 95% CL
-1 = 8 TeV, L = 19.6 fbsCMS
4/8/15 17
W+W- Anomalous coupling • BSM processes parameterized by series of higher-dimensional operators
that are the low-energy description of interactions mediated by unknown massive fields. (E.g. Fermi Lagrangian).
• Considering only C and P conserving operators and mass scale of new physic Λ large enough we have the following 6 dimension operators:
A binned Poisson log-likelihood computed on the invariant mass of the two charged leptons.
4/8/15 18
W+W- Anomalous coupling
(GeV)llm100 200 300 400 500 600
Even
ts /
(75
GeV
)
10
210
310
410 DataWWWZ/ZZ/VVV
TopDYW+jets
-2 = 20 TeV2Λ/Wc-2 = 20 TeV2Λ/WWWc
-2 = 55 TeV2Λ/Bc
CMS (8 TeV)-119.4 fbPreliminary
)-2 (TeV2Λ/Wc-20 -15 -10 -5 0 5 10 15 20
)-2
(TeV
2Λ/ Bc
-60
-40
-20
0
20
40
60
80 (8 TeV)-119.4 fbCMS Preliminary
Observed 68% CLObserved 95% CLExpected 68% CLExpected 95% CL
4/8/15 19
Future projection WZ • 300 fb-1 (Phase 1) with 50 pile-
up event and similar detector • 3000 fb-1 (Phase 2) with 140
pile-up events and with the detector upgrade (new tracker and Ecal, mu-detection down toη< 4)
4/8/15 20