Multi-boson production measurements with the CMS detector

Gian Luca Pinna Angioni

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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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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

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ZZ

WZ/Z + jets

-1 = 8 TeV, L = 19.6 fbsCMS

(GeV)ττllm200 400 600 800 1000

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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

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0

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1Unfolded dataTotal uncertainty

ZZMCFM NLO

CMS -1 = 8 TeV, L = 19.6 fbs

Unfolded dataTotal uncertainty

ZZMCFM NLO

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a/M

C0

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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

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= 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

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io D

ata/

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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

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bin

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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

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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

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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

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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

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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

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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

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Data Madgraph MC@NLO Powheg

CMS Preliminary (8 TeV)-119.4 fb

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NNLOσMadgraph+Pythia normalized to

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NNLOσMC@NLO+Herwig normalized to

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NNLOσPowheg+Pythia normalized to

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ll(W

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Data Madgraph MC@NLO Powheg

CMS Preliminary (8 TeV)-119.4 fb

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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

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Data Madgraph MC@NLO Powheg

CMS Preliminary (8 TeV)-119.4 fb

(GeV)llm20 40 60 80 100 120 140 160 180 200

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NNLOσMadgraph+Pythia normalized to

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NNLOσMC@NLO+Herwig normalized to

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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

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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

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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.

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W+W- Anomalous coupling

(GeV)llm100 200 300 400 500 600

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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

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80 (8 TeV)-119.4 fbCMS Preliminary

Observed 68% CLObserved 95% CLExpected 68% CLExpected 95% CL

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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)

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