ETH Zu¨rich γγ H Nicolas Chanon Modeling of Diboson+jets ......γγ Zγ WW ZZ Fig. 2: Higgs...

H → γγ sensitivity studies using RooStats

H → γγ W.G. meetingH → γγ W.G. meetingNicolas Chanon, ETHGregory Schott, KIT

Hugues Brun, Suzanne Gascon-Shotkin, Morgan Lethuillier, IPNL

ETH Zurich

11/02/2011

Nicolas Chanon H → γγ sensitivity studies using RooStats 1 / 7

1

Modeling of Diboson+jets and Higgs+jets at CMS

8/12/2014 - Higgs+Jets 2014 workshop, IPPP Durham

Nicolas Chanon - IPHC Strasbourgon behalf of the CMS collaboration




ETH Zurich

11/02/2011


Introduction

2

- This workshop: aims at reviewing state of the art Higgs and Higgs+jet kinematics in theoretical predictions and data measurement

- see previous talks from ATLAS on Higgs differential measurement

- V+jets can be seen as a benchmark for Higgs jet multiplicities modeling- see V+jets talk later this afternoon

- VV+jets is an irreducible background to H→VV decays and also an interesting benchmark for NNLO and multijet computations

- In this talk I will focus on jet modeling in H→γγ, H→ZZ and H→WW analyses, and what we learned about jets with γγ, ZZ, WW measurements, that may be useful for the Higgs.




ETH Zurich

11/02/2011


3parameter value0 1 2 3 4 5 6

ttHµ

VHµ

VBFµ

ggHµ

68% CL95% CL

CMSPreliminary

(7 TeV)-1 (8 TeV) + 5.1 fb-119.7 fb

68% CL95% CL

H→VV summaryPAS HIG-14-009

Higgs boson signal strength μ=σ/σSM

by production mechanism

and final state tag

ggH: - NNLO normalization- Shape from Powheg

VBF: - NNLO normalization- Shape from Powheg

VH: - NNLO normalization- Shape from Pythia

ttH: - NLO normalization- Shape from Pythia




ETH Zurich

11/02/2011


4theoσ / expσProduction Cross Section Ratio: 0.5 1 1.5 2

CMS PreliminaryApr 2014

All results at:http://cern.ch/go/pNj7

(NNLO th.), γγ 0.09± 0.11 ±1.04 -15.0 fbγW 0.06± 0.13 ±1.16 -15.0 fbγZ 0.05± 0.05 ±0.98 -15.0 fb

WW+WZ 0.03± 0.20 ±1.05 -14.9 fbWW 0.04± 0.11 ±1.11 -14.9 fbWW 0.04± 0.12 ±1.22 -13.5 fbWZ 0.03± 0.10 ±1.17 -14.9 fbWZ 0.05± 0.08 ±1.12 -119.6 fbZZ 0.06± 0.15 ±0.99 -14.9 fbZZ 0.08± 0.10 ±1.00 -119.6 fb

7 TeV CMS measurement (exp+th)

8 TeV CMS measurement (exp+th)

CMS measurementsvs. NLO theory

VV summaryhttps://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP

Diboson productionData / NLO cross-section ratio

Recent progress in NNLO computation:- Diphoton, Zγ, Wγ

differential available- WW, ZZ inclusive cross-

section available- Only WZ is missing !

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP




ETH Zurich

11/02/2011


H→γγ

5

[GeV]HM100 120 140 160 180 200

Higg

s BR

+ T

otal

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ert

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-110

1

LHC

HIG

GS

XS W

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[GeV]HM100 200 300 400 500 1000

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+ T

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ert

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-110

1

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HIG

GS

XS W

G 2

011

bb

ττ

cc

ttgg

γγ γZ

WW

ZZ

Fig. 2: Higgs branching ratios and their uncertainties for the low mass range (left) and for the full mass range(right).

[GeV]HM100 200 300 400 500 1000

Higg

s BR

+ T

otal

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ert

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011

τ,µllll, l=e,µllll, l=e,

eeeeµµee

=anyν, τ,µ, l=e,ννll=anyν, µ, l=e,ννll

ν eνeν µ νe

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s BR

+ T

otal

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ert

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011

, q=udcsbτ,µllqq, l=e,, q=udcsbµllqq, l=e,

=any, q=udcsbνqq, νν

, q=udcsbµqq, l=e,νl

qqqq, q=udcsb

ffff, f=any fermion

Fig. 3: Higgs branching ratios for the different H → 4l and H → 2l2ν final states (left) and for H → 4q, H → 4f

and H → 2q2l, 2qlν, 2q2ν final states (right) and their uncertainties for the full mass range.

are correlated for MH > 500 GeV or small below, we only consider the simultaneous scaling of all4-fermion partial widths. The thus obtained individual theoretical uncertainties for the branching ratiosare combined linearly to obtain the total theoretical uncertainties.

Finally, the total uncertainties are obtained by adding linearly the total parametric uncertaintiesand the total theoretical uncertainties.

2.1.4 ResultsIn this section the results of the SM Higgs branching ratios, calculated according to the procedure de-scribed above, are shown and discussed. Figure 2 shows the SM Higgs branching ratios in the low massrange, 100 GeV < MH < 200 GeV, and in the “full” mass range, 100 GeV < MH < 1000 GeV, assolid lines. The (coloured) bands around the lines show the respective uncertainties, estimated consid-ering both the theoretical and the parametric uncertainty sources (as discussed in Section 2.1.3). Moredetailed results on the decays H → WW and H → ZZ with the subsequent decay to 4f are presented inFigures 3. The largest “visible” uncertainties are found for the channels H → τ+τ−, H → gg, H → cc,and H → tt, see below.

In the following we list the branching ratios for the Higgs two-body fermionic and bosonic finalstates, together with their uncertainties, estimated as discussed in Section 2.1.3. Detailed results for fourrepresentative Higgs-boson masses are given in Table 3. Here we show the BR, the PU separately for

8

Zürich Phenomenology Workshop

Beyond the Standard ModelTest processes induced by loop diagrams

BRBSM

=�

BSM

�tot

Scan BRBSM and profile κV κf

t/W

BRBSM below 0.62 at 95% CL39

Set ΓBSM =0

BR(H→γγ)~2.10-3

Cro

ss-s

ectio

n (p

b)

-310

-210

-1101

10

210

310

410

510

610

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810

910 Dijet

!Inc. +jet!

!!

!!"H

Diphoton production




ETH Zurich

11/02/2011


H→γγ analysisEPJC 74 (2014) 3076

6

- Look for small signal peak (small BR) over large background- Main analysis is MVA - cut-based analysis and 2nd MVA analyses as cross-checks- Select two high pt isolated photons from the same vertex

Large background from diphoton continuum (~70%) (after photon Id)

- Photon identification BDT to reject jets faking photons: shower shape and isolation

(GeV)γγm100 120 140 160 180

Even

ts/2

GeV

02468

101214161820

310×

Dataγ-γ

-jetγjet-jetDrell-Yan

(125 GeV) x5γγ→H

(8 TeV)-1

19.7 fb

CMSUnpublishedPhoId BDT

outputCro

ss-s

ectio

n (p

b)

-310

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-1101

10

210

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410

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610

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810

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!Inc. +jet!

!!

!!"H




ETH Zurich

11/02/2011


Diphoton cross-section (7 TeV)EPJC 74 (2014) 3129

7

- Kinematical range: |ηγ|<2.5, ET,γ1>40, ET,γ2>25 GeV, ΔR(γ1,γ2)>0.45- Differential cross-section measured as a function of Mγγ, PT,γγ, ΔΦ(γ1,γ2), cos(θ*)- Background: boosted neutral mesons (π0→γγ) reconstructed as a single γ (fake)- Method: particle-flow photon isolation template to subtract statistically the background- Purely data-driven: ~10% systematic uncertainties

(GeV)1Iso-2 0 2 4 6 8

Even

ts /

( 0.1

25 G

eV )

0

100

200

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Signal comp.

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-1 = 7 TeV L = 5.0 fbsCMS

(GeV)2Iso-2 0 2 4 6 8

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( 0.1

25 G

eV )

0

200

400

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Fit

Signal comp.

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< 95 GeVγγEB-EE, 90 GeV < m

(GeV)γ γ

m0 100 200 300 400 500 600 700 800

Frac

tion

0

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0.2

0.3

0.4

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0.6

0.7

0.8

0.9

1Prompt - PromptPrompt - Non-promptNon-prompt - Non-prompt





ETH Zurich

11/02/2011


Diphoton cross-section (7 TeV)EPJC 74 (2014) 3129

8

- NNLO predictions improve a lot the data/MC agreement

- Sherpa (up to 3 ME extra-jets) shows also a good agreement

- Still an excess in data at low ΔΦ (sensitive to missing higher order QCD effects)

0 0.5 1 1.5 2 2.5 3

(pb/

rad)

γγφ

/dσ∆d

-110

1

10

Data

SHERPA

RESBOS


0 1 2 3Data

/SHE

RPA

01234

(radian)γγ

φ∆0 1 2 3Da

ta/R

ESBO

S

01234

0 0.5 1 1.5 2 2.5 3 (p

b/ra

d)γγφ

/dσ∆d

-110

1

10

Data

DIPHOX+GAMMA2MC

NNLOγ2


0 1 2 3Data

/DIP

HOX

01234

(radian)γγ

φ∆0 1 2 3

NNLO

γDa

ta/2

01234




ETH Zurich

11/02/2011


Backgrounds in H→γγEPJC 74 (2014) 3076

9

- Excellent agreement of diphoton sherpa with data also in H→γγ searches- Gamma+jet and dijet with Pythia and k-factor estimated from XS measurements- Models adequately difficult observables like diphoton mass and diphoton BDT

output- But MC is not used to evaluate the background, only to train the BDTs

(GeV)γγm100 120 140 160 180

Even

ts/2

GeV

02468

101214161820

310×

Dataγ-γ

-jetγjet-jetDrell-Yan

(125 GeV) x5γγ→H

(8 TeV)-1

19.7 fb

CMSUnpublished




ETH Zurich

11/02/2011


H→γγ: categoriesEPJC 74 (2014) 3076

10

Diphoton BDT - Mass independant- Kinematics, vertexing,

PhotonId output, energy resolution variables

Sensitivity from mass fit. Bkgd: Bernstein polynomial (bias <20% stat uncertainty)

Cat 3 Cat 2 Cat 1 Cat 0




ETH Zurich

11/02/2011


H→γγ: VBF categoriesEPJC 74 (2014) 3076

11

Categories: - Defined with s/b and resolution level- 5 untagged, 3 VBF categories, 3 VH cat, 2 ttH

VBF tags:- VBF is higher γγ pT, two forward jets- Dijet BDT using γγ, jets kinematics- Define two categories: s/b~0.5 and

s/b~0.2

Gluon-gluon fusion contamination in VBF categories ~20-50%Uncertainty:- Stewart-Tackmann procedure: QCD scale

uncertainty from Δσ = Δσ1 ⊕ Δσ2

VBF tight




ETH Zurich

11/02/2011


Spin measurement with H→γγEPJC 74 (2014) 3076

12

- Cut-based analysis to minimize model-dependence- Measurement of signal yield in bins of cos(θ*): μ differential measurement- No unfolding- Testing minimal graviton couplings, spin 2+ gluon fusion or qqbar initiated




ETH Zurich

11/02/2011


H→ZZ→4l

13 [GeV]HM

100 120 140 160 180 200

Higg

s BR

+ T

otal

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+ T

otal

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ert

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1

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HIG

GS

XS W

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011




qqqq, q=udcsb

ffff, f=any fermion







8




ETH Zurich

11/02/2011


ZZ→4l and H→ZZ(*)→4l

14

Z→4l:- XS x BR

measurement

H→ZZ*→4l:- Very good s/b~2- 3D analysis

- ZZ→4l: onshell Z’s- differential cross-section- aTGC

Signature:2 pair of opposite sign isolated leptons (4e, 2e2μ, 4μ) consistent with the same vertex




ETH Zurich

11/02/2011


ZZ→4l cross-sectionarxiv:1406.0113 (accepted by PLB)

15

)2

, Z1

(Zφ ∆0 0.5 1 1.5 2 2.5 3

)) 2, Z 1

(Zφ ∆

/d(

fidσ

d

fidσ

1/

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7 Unfolded dataTotal uncertainty

ZZMCFM NLO

CMS -1 = 8 TeV, L = 19.6 fbs

Unfolded dataTotal uncertainty

ZZMCFM NLO

Dat

a/M

C

0123

(GeV)T

ZZ p0 20 40 60 80 100 120 140

) (1/

GeV

)T

/d(Z

Z p

fidσ

d

fidσ

1/

0

0.2

0.4

0.6

0.8

1

1.2Unfolded dataTotal uncertainty

ZZMCFM NLO

CMS -1 = 8 TeV, L = 19.6 fbs

Unfolded dataTotal uncertainty

ZZMCFM NLO

Dat

a/M

C

0

1

2

- Background subtraction: Z+jets (estimated with inverted isolation), ttbar

- Inclusive and differential cross-sections

“ZZ”: Powheg qq+ggZZ

√s (TeV) σLO (pb) σNLO (pb) σNNLO (pb)

7 4.167+0.7%−1.6% 6.044+2.8%

−2.2% 6.735+2.9%−2.3%

8 5.060+1.6%−2.7% 7.369+2.8%

−2.3% 8.284+3.0%−2.3%

9 5.981+2.4%−3.5% 8.735+2.9%

−2.3% 9.931+3.1%−2.4%

10 6.927+3.1%−4.3% 10.14+2.9%

−2.3% 11.60+3.2%−2.4%

11 7.895+3.8%−5.0% 11.57+3.0%

−2.4% 13.34+3.2%−2.4%

12 8.882+4.3%−5.6% 13.03+3.0%

−2.4% 15.10+3.2%−2.4%

13 9.887+4.9%−6.1% 14.51+3.0%

−2.4% 16.91+3.2%−2.4%

14 10.91+5.4%−6.7% 16.01+3.0%

−2.4% 18.77+3.2%−2.4%

Table 1: Inclusive cross section for ZZ production at the LHC at LO, NLO and NNLO withµF = µR = mZ . The uncertainties are obtained by varying the renormalization and factorizationscales in the range 0.5mZ < µR, µF < 2mZ with the constraint 0.5 < µF/µR < 2.

does not cover the NNLO effect. This is not unexpected since the gluon fusion channel, whichprovides a rather large contribution, opens up only at NNLO.

We have reported the first calculation of the inclusive cross section for the production of on-shell Z-boson pairs at the LHC up to NNLO in QCD perturbation theory. The NNLO correctionsincrease the NLO result by an amount varying from 11% to 17% as

√s ranges from 7 to 14 TeV. The

loop-induced gluon fusion contribution provides more than half of the complete NNLO effect. Ourcalculation of the total cross section is based on the two-loop matrix element for qq → ZZ for on-shell Z bosons. A computation of the two-loop helicity amplitudes will open up a spectrum of moredetailed phenomenological studies at NNLO, including off-shell effects, differential distributionsof the Z boson decay products and direct comparison with the experimentally measured fiducialcross sections.

Acknowledgements. We would like to thank A. Denner, S. Dittmaier and L. Hofer for pro-viding us with the Collier library. This research was supported in part by the Swiss Na-tional Science Foundation (SNF) under contracts CRSII2-141847, 200021-144352, 200020-149517,PP00P2-128552 and by the Research Executive Agency (REA) of the European Union underthe Grant Agreements PITN–GA—2010-264564 (LHCPhenoNet), PITN–GA–2012–316704 (Hig-gsTools), and the ERC Advanced Grant MC@NNLO (340983).

References

[1] T. Aaltonen et al. [CDF Collaboration], Phys. Rev. Lett. 108 (2012) 101801 [arXiv:1112.2978[hep-ex]].

4

√s (TeV) σLO (pb) σNLO (pb) σNNLO (pb)

7 4.167+0.7%−1.6% 6.044+2.8%

−2.2% 6.735+2.9%−2.3%

8 5.060+1.6%−2.7% 7.369+2.8%

−2.3% 8.284+3.0%−2.3%

9 5.981+2.4%−3.5% 8.735+2.9%

−2.3% 9.931+3.1%−2.4%

10 6.927+3.1%−4.3% 10.14+2.9%

−2.3% 11.60+3.2%−2.4%

11 7.895+3.8%−5.0% 11.57+3.0%

−2.4% 13.34+3.2%−2.4%

12 8.882+4.3%−5.6% 13.03+3.0%

−2.4% 15.10+3.2%−2.4%

13 9.887+4.9%−6.1% 14.51+3.0%

−2.4% 16.91+3.2%−2.4%

14 10.91+5.4%−6.7% 16.01+3.0%

−2.4% 18.77+3.2%−2.4%

Table 1: Inclusive cross section for ZZ production at the LHC at LO, NLO and NNLO withµF = µR = mZ . The uncertainties are obtained by varying the renormalization and factorizationscales in the range 0.5mZ < µR, µF < 2mZ with the constraint 0.5 < µF/µR < 2.

does not cover the NNLO effect. This is not unexpected since the gluon fusion channel, whichprovides a rather large contribution, opens up only at NNLO.

We have reported the first calculation of the inclusive cross section for the production of on-shell Z-boson pairs at the LHC up to NNLO in QCD perturbation theory. The NNLO correctionsincrease the NLO result by an amount varying from 11% to 17% as

√s ranges from 7 to 14 TeV. The

loop-induced gluon fusion contribution provides more than half of the complete NNLO effect. Ourcalculation of the total cross section is based on the two-loop matrix element for qq → ZZ for on-shell Z bosons. A computation of the two-loop helicity amplitudes will open up a spectrum of moredetailed phenomenological studies at NNLO, including off-shell effects, differential distributionsof the Z boson decay products and direct comparison with the experimentally measured fiducialcross sections.

Acknowledgements. We would like to thank A. Denner, S. Dittmaier and L. Hofer for pro-viding us with the Collier library. This research was supported in part by the Swiss Na-tional Science Foundation (SNF) under contracts CRSII2-141847, 200021-144352, 200020-149517,PP00P2-128552 and by the Research Executive Agency (REA) of the European Union underthe Grant Agreements PITN–GA—2010-264564 (LHCPhenoNet), PITN–GA–2012–316704 (Hig-gsTools), and the ERC Advanced Grant MC@NNLO (340983).

References

[1] T. Aaltonen et al. [CDF Collaboration], Phys. Rev. Lett. 108 (2012) 101801 [arXiv:1112.2978[hep-ex]].

4

- New NNLO total cross-section [hep-ph:1405.2219]

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)

CERN-PH-EP/2014-0802014/06/03

CMS-SMP-13-005

Measurement of the pp ! ZZ production cross section andconstraints on anomalous triple gauge couplings in

four-lepton final states atp

s = 8 TeV

The CMS Collaboration⇤

Abstract

A measurement of inclusive ZZ production cross section and constraints on anoma-lous triple gauge couplings in proton-proton collisions at

ps = 8 TeV are presented.

A data sample, corresponding to an integrated luminosity of 19.6 fb�1 was collectedwith the CMS experiment at the LHC. The measurements are performed in the lep-tonic decay modes ZZ ! ```0`0, where ` = e, µ and `0 = e, µ, t. The measured to-tal cross section, s(pp ! ZZ) = 7.7 ± 0.5 (stat.) +0.5

�0.4 (syst.) ± 0.4 (th.)± 0.2 (lum.) pbfor both Z bosons produced in the mass range 60 < mZ < 120 GeV, is consistentwith standard model predictions. Differential cross sections are measured and welldescribed by the theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZg couplings at the 95%confidence level: �0.004 < f Z

4 < 0.004, �0.005 < f Z5 < 0.005, �0.004 < f g

4 < 0.004,and �0.005 < f g

5 < 0.005.

Submitted to Physics Letters B

c� 2014 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license

⇤See Appendix 10 for the list of collaboration members

arX

iv:1

406.

0113

v1 [

hep-

ex]

31 M

ay 2

014




ETH Zurich

11/02/2011


16

- 0,1jet Kinematic discriminant (KD): Matrix element method using invariant mass of Z1 and Z2 and 5 angular variables.

2

FIG. 1: Illustration of an exotic X particle production and decay in pp collision gg or qq → X → ZZ → 4l±. Six angles fullycharacterize orientation of the decay chain: θ∗ and Φ∗ of the first Z boson in the X rest frame, two azimuthal angles Φ and Φ1

between the three planes defined in the X rest frame, and two Z-boson helicity angles θ1 and θ2 defined in the correspondingZ rest frames. The offset of angle Φ∗ is arbitrarily defined and therefore this angle is not shown.

discussed in Refs. [21–23] KK graviton decays into pairs of gauge bosons are enhanced relative to direct decays intoleptons. Similar situations may occur in “hidden-valley”-type models [24]. An example of a ”heavy photon” is givenin Ref. [25].Motivated by this, we consider the production of a resonance X at the LHC in gluon-gluon and quark-antiquark

partonic collisions, with the subsequent decay of X into two Z bosons which, in turn, decay leptonically. In Fig. 1,we show the decay chain X → ZZ → e+e−µ+µ−. However, our analysis is equally applicable to any combination ofdecays Z → e+e− or µ+µ−. It may also be applicable to Z decays into τ leptons since τ ’s from Z decays will often behighly boosted and their decay products collimated. We study how the spin and parity of X , as well as informationon its production and decay mechanisms, can be extracted from angular distributions of four leptons in the final state.There are a few things that need to be noted. First, we obviously assume that the resonance production and

its decays into four leptons are observed. Note that, because of a relatively small branching fraction for leptonic Zdecays, this assumption implies a fairly large production cross-section for pp → X and a fairly large branching fractionfor the decay X → ZZ. As we already mentioned, there are well-motivated scenarios of BSM physics where thoserequirements are satisfied.Second, having no bias towards any particular model of BSM physics, we consider the most general couplings of the

particle X to relevant SM fields. This approach has to be contrasted with typical studies of e.g. spin-two particlesat hadron colliders where such an exotic particle is often identified with a massive graviton that couples to SM fieldsthrough the energy-momentum tensor. We will refer to this case as the “minimal coupling” of the spin-two particleto SM fields.The minimal coupling scenarios are well-motivated within particular models of New Physics, but they are not

sufficiently general. For example, such a minimal coupling may restrict partial waves that contribute to the productionand decay of a spin-two particle. Removing such restriction opens an interesting possibility to understand the couplingsof a particle X to SM fields by means of partial wave analyses, and we would like to set a stage for doing that in thispaper. To pursue this idea in detail, the most general parameterization of the X coupling to SM fields is required.Such parameterizations are known for spin-zero, spin-one, and spin-two particles interacting with the SM gaugebosons [7, 8] and we use these parameterizations in this paper. We also note that the model recently discussed inRefs. [21–23] requires couplings beyond the minimal case in order to produce longitudinal polarization dominance.Third, we note that while we concentrate on the decay X → ZZ → l+1 l

−1 l

+2 l

−2 , the technique discussed in this

paper is more general and can, in principle, be applied to final states with jets and/or missing energy by studyingsuch processes as X → ZZ → l+l−jj, X → W+W− → l+νjj, etc. In contrast with pure leptonic final states,higher statistics, larger backgrounds, and a worse angular resolution must be expected once final states with jets and

H→ZZ(*)→4l analysisPRD 89 (2014) 092007

KD in Signal MC

(GeV)l4m120 130 140 150 160 170 180

bkg

kin

D

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jetD0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

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8Data

*�ZZ , Z

Z+X

= 126 GeV)HmH (tggH+t

= 126 GeV)HmVBF+VH (

< 130.5 GeVl4m121.5 < < 130.5 GeVl4m121.5 <


Fisher discriminant

- Sizeable guon fusion contamination in 2jet bin

2-jets: Fischer discriminant with jet information

- 3D analysis in Mass, KD, and pT(H) (untagged), and Mass, KD, Fischer discriminant (dijet tag)

Results:




ETH Zurich

11/02/2011


H→ZZ(*)→4l: Higgs pTPRD 89 (2014) 092007

17 (GeV)l4Tp

0 20 40 60 80 100 120 140 160 180 200

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8Data

*γZZ , Z

Z+X

= 126 GeV)HmH (tggH+t

= 126 GeV)HmVBF+VH (

< 130.5 GeVl4m121.5 < < 130.5 GeVl4m121.5 <


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< 130.5 GeVl4m121.5 <

CMS

0,1 jetsall jets

- Higgs pT measured using s-plot method, using m4l only for background weights estimation

- 4l pT without background subtraction, in Higgs mass window:




ETH Zurich

11/02/2011

Nicolas Chanon H → γγ sensitivity studies using RooStats 1 / 7 H→WW

18

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otal

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ert

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qqqq, q=udcsb

ffff, f=any fermion







8




ETH Zurich

11/02/2011


H→W+W- analysisJHEP 01 (2014) 096

H→WW→2l2ν analysis: High BR, but no mass peak (resolution is ~20%)- Two isolated leptons with pT>20,10 GeV and mET>20 GeV- CategorIES: 0-jet, 1-jet, 2-jet bins, then ee,μμ,eμ with opposite charge- Main backgrounds: WW, top (1,2jet bins), W+jets (estimated from control regions in data)

[GeV]llm0 100 200 300

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10 G

eV

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1000

data WW→ H

W+jets

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top DY+jets

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0-jet bin

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10 G

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data WW→ H

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W+jets

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Figure 12: Distributions of the dilepton mass (left) in the same-charge dilepton control regionin the 0-jet category and the transverse mass (right) in the top-tagged control region in the 1-jetcategory of the eµ final state.

been tested in dedicated control regions with data. Both the fit procedure and the backgroundestimations are found to be very robust.

Finally, the template shape for the dominant qq ! WW background process has been cross-checked by replacing the template histogram obtained from the default generator by anotherone and rederiving the shape uncertainty templates that are allowed to vary in the fit. Table 8summarizes the results of this procedure using MADGRAPH (a priori default used in the analy-sis), MC@NLO, and POWHEG. The signal significance, and the best-fit signal strength are foundto be consistent with one another for the three different qq ! WW template models tested.

Table 8: A summary of the expected and observed 95% CL upper limits on the H ! WW pro-duction cross section relative to the SM prediction, significances in units of standard deviations(sd), and the best-fit value of s/sSM for the SM Higgs boson with a mass of 125 GeV for the 0-jetand 1-jet categories using the template fit to (mT, m``), where three different generators havebeen used to model the qq ! WW background process.

qq ! WW 95% CL limits on s/sSM Significance s/sSMgenerator expected / observed expected / observed observedMADGRAPH (default) 0.4 / 1.2 5.2 / 4.0 sd 0.76 ± 0.21MC@NLO 0.4 / 1.2 5.3 / 4.2 sd 0.82 ± 0.24POWHEG 0.4 / 1.2 5.1 / 3.9 sd 0.74 ± 0.21

6.3 The two-jet VBF tag

The second-largest production mode for the SM Higgs boson is through VBF, for which thecross section is approximately an order of magnitude smaller than that of the gluon fusionprocess. In this process two vector bosons are radiated from initial-state quarks and producea Higgs boson at tree level. In the scattering process, the two initial-state partons may scatterat a polar angle from the beam axis large enough to be detected as additional jets in the signalevents. Furthermore, these two jets, being remnants of the incoming proton beams, feature

qq→WW background modeling is crucial !

2D analysis in (mT, mll) for the opposite flavor 0-jet and 1-jet bins (cross-check with a 2nd 2D analysis)




ETH Zurich

11/02/2011


WW cross-sectionEPJC 73 (2013) 2610

20 [GeV]max

Tp

0 50 100 150

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syst⊕ stat

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syst⊕ stat

CMS -1 = 8 TeV, L = 3.5 fbs

Inclusive WW cross-section- Fakes from inverted isolation- Measurement performed in 0-jet bin (so far)- Jet veto QCD scale uncertainty 4.6%- Unfolding to inclusive cross-section

3

√s

TeV σLO σNLO σNNLO σgg→H→WW∗

7 29.52+1.6%−2.5% 45.16+3.7%

−2.9% 49.04+2.1%−1.8% 3.25+7.1%

−7.8%

8 35.50+2.4%−3.5% 54.77+3.7%

−2.9% 59.84+2.2%−1.9% 4.14+7.2%

−7.8%

13 67.16+5.5%−6.7% 106.0+4.1%

−3.2% 118.7+2.5%−2.2% 9.44+7.4%

−7.9%

14 73.74+5.9%−7.2% 116.7+4.1%

−3.3% 131.3+2.6%−2.2% 10.64+7.5%

−8.0%

TABLE I. LO, NLO and NNLO cross sections (in picobarn)for on-shell W+W− production in the 4FNS and referenceresults for gg → H → WW ∗ from Ref. [75].

decrease when moving from LO to NLO and NNLO.Moreover, the NNLO (NLO) corrections turn out to ex-ceed the scale uncertainty of the NLO (LO) predictionsby up to a factor 3 (34). The fact that LO and NLOscale variations underestimate higher-order effects can beattributed to the fact that the gluon–quark and gluon–gluon induced partonic channels, which yield a sizablecontribution to the W+W− cross section, appear onlybeyond LO and NLO, respectively. The NNLO is thefirst order at which all partonic channels are contribut-ing. The NNLO scale dependence, which amounts toabout 3%, can thus be considered a realistic estimate ofthe theoretical uncertainty due to missing higher-ordereffects.

In Figure 1, theoretical predictions in the 4FNS arecompared to CMS and ATLAS measurements at 7 and8 TeV [5–8]. For a consistent comparison, our resultsfor on-shell W+W− production are combined with thegg → H → WW ∗ cross sections reported in Table I.It turns out that the inclusion of the NNLO correctionsleads to an excellent description of the data at 7 TeV anddecreases the significance of the observed excess at 8 TeV.In the lower frame of Figure 1, predictions and scale vari-ations at NNLO are compared to NLO ones, and also theindividual contribution of the gg → W+W− channel isshown. Using NNLO parton distributions throughout,the loop induced gluon fusion contribution is only about35% of the total NNLO correction.

In the light of the small scale dependence of the 4FNSNNLO cross section, the ambiguities associated with thedefinition of a top-free W+W− cross section and its sen-sitivity to the choice of the FNS might represent a sig-nificant source of theoretical uncertainty at NNLO. Inparticular, the omission of b-quark emissions in our 4FNSdefinition of the W+W− cross section implies potentiallylarge logarithms of mb in the transition from the 4FNSto the 5FNS. To quantify this kind of uncertainties, westudy the NNLO W+W− cross section in the 5FNS andintroduce a subtraction of its top contamination that al-lows for a consistent comparison between the two FNSs.An optimal definition of W+W− production in the 5FNSrequires maximal suppression of the top resonances in

σ/σNLO

141387

1.15

1.1

1.05

1.00

0.95

CMSATLAS

added to all predictions

gg → H → WW∗

σ[pb]

√s [TeV]

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120

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gg → H → WW∗

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120

100

80

60

40

20

FIG. 1. The on-shell W+W− cross section in the 4FNS at

LO (dots), NLO (dashes), NLO+gg (dot dashes) and NNLO

(solid) combined with gg → H → WW ∗ is compared to re-

cent ATLAS and CMS measurements [5–8]. In the lower panel

NNLO and NLO+gg results are normalized to NLO predic-

tions. The bands describe scale variations.

the pp → W+W−b and pp → W+W−bb channels. Atthe same time, the cancellation of collinear singularitiesassociated with massless g → bb splittings requires a suf-ficient level of inclusiveness. The difficulty of fulfillingboth requirements is clearly illustrated in Figure 2 (left),where 5FNS predictions are plotted versus a b-jet vetothat rejects b-jets with pT,bjet > pvetoT,bjet over the wholerapidity range, and are compared to 4FNS results. Inthe inclusive limit, pvetoT,bjet → ∞, the higher-order correc-tions in the 5FNS suffer from a huge top contamination.At 7 (14) TeV the resulting relative enhancement withrespect to the 4FNS amounts to about 30 (60)% at NLOand a factor 4 (8) at NNLO. In principle, it can be sup-pressed through the b-jet veto. However, for natural jetveto values around 30 GeV the top contamination re-mains larger than 10% of the W+W− cross section, anda complete suppression of the top contributions requiresa veto of the order of 1 GeV. Moreover, as pvetoT,bjet → 0,the (N)NLO cross section does not approach a constant,but, starting from pvetoT,bjet ∼ 10 GeV, it displays a loga-rithmic slope due to singularities associated with initialstate g → bb splittings. This sensitivity to the jet-vetoparameters represents a theoretical ambiguity at the sev-eral percent level, which is inherent in the definition oftop-free W+W− production based on a b-jet veto.

To circumvent this problem we will adopt an alterna-

3

√s

TeV σLO σNLO σNNLO σgg→H→WW∗

7 29.52+1.6%−2.5% 45.16+3.7%

−2.9% 49.04+2.1%−1.8% 3.25+7.1%

−7.8%

8 35.50+2.4%−3.5% 54.77+3.7%

−2.9% 59.84+2.2%−1.9% 4.14+7.2%

−7.8%

13 67.16+5.5%−6.7% 106.0+4.1%

−3.2% 118.7+2.5%−2.2% 9.44+7.4%

−7.9%

14 73.74+5.9%−7.2% 116.7+4.1%

−3.3% 131.3+2.6%−2.2% 10.64+7.5%

−8.0%

TABLE I. LO, NLO and NNLO cross sections (in picobarn)for on-shell W+W− production in the 4FNS and referenceresults for gg → H → WW ∗ from Ref. [75].

decrease when moving from LO to NLO and NNLO.Moreover, the NNLO (NLO) corrections turn out to ex-ceed the scale uncertainty of the NLO (LO) predictionsby up to a factor 3 (34). The fact that LO and NLOscale variations underestimate higher-order effects can beattributed to the fact that the gluon–quark and gluon–gluon induced partonic channels, which yield a sizablecontribution to the W+W− cross section, appear onlybeyond LO and NLO, respectively. The NNLO is thefirst order at which all partonic channels are contribut-ing. The NNLO scale dependence, which amounts toabout 3%, can thus be considered a realistic estimate ofthe theoretical uncertainty due to missing higher-ordereffects.

In Figure 1, theoretical predictions in the 4FNS arecompared to CMS and ATLAS measurements at 7 and8 TeV [5–8]. For a consistent comparison, our resultsfor on-shell W+W− production are combined with thegg → H → WW ∗ cross sections reported in Table I.It turns out that the inclusion of the NNLO correctionsleads to an excellent description of the data at 7 TeV anddecreases the significance of the observed excess at 8 TeV.In the lower frame of Figure 1, predictions and scale vari-ations at NNLO are compared to NLO ones, and also theindividual contribution of the gg → W+W− channel isshown. Using NNLO parton distributions throughout,the loop induced gluon fusion contribution is only about35% of the total NNLO correction.

In the light of the small scale dependence of the 4FNSNNLO cross section, the ambiguities associated with thedefinition of a top-free W+W− cross section and its sen-sitivity to the choice of the FNS might represent a sig-nificant source of theoretical uncertainty at NNLO. Inparticular, the omission of b-quark emissions in our 4FNSdefinition of the W+W− cross section implies potentiallylarge logarithms of mb in the transition from the 4FNSto the 5FNS. To quantify this kind of uncertainties, westudy the NNLO W+W− cross section in the 5FNS andintroduce a subtraction of its top contamination that al-lows for a consistent comparison between the two FNSs.An optimal definition of W+W− production in the 5FNSrequires maximal suppression of the top resonances in

σ/σNLO

141387

1.15

1.1

1.05

1.00

0.95

CMSATLAS


gg → H → WW∗

σ[pb]

√s [TeV]

pp → W+W−+X140

120

100

80

60

40

20 LONN+ggNLON+ggNLO+ggNNNLO+gg


gg → H → WW∗

σ[pb]

√s [TeV]

pp → W+W−+X140

120

100

80

60

40

20

FIG. 1. The on-shell W+W− cross section in the 4FNS at

LO (dots), NLO (dashes), NLO+gg (dot dashes) and NNLO

(solid) combined with gg → H → WW ∗ is compared to re-

cent ATLAS and CMS measurements [5–8]. In the lower panel

NNLO and NLO+gg results are normalized to NLO predic-

tions. The bands describe scale variations.

the pp → W+W−b and pp → W+W−bb channels. Atthe same time, the cancellation of collinear singularitiesassociated with massless g → bb splittings requires a suf-ficient level of inclusiveness. The difficulty of fulfillingboth requirements is clearly illustrated in Figure 2 (left),where 5FNS predictions are plotted versus a b-jet vetothat rejects b-jets with pT,bjet > pvetoT,bjet over the wholerapidity range, and are compared to 4FNS results. Inthe inclusive limit, pvetoT,bjet → ∞, the higher-order correc-tions in the 5FNS suffer from a huge top contamination.At 7 (14) TeV the resulting relative enhancement withrespect to the 4FNS amounts to about 30 (60)% at NLOand a factor 4 (8) at NNLO. In principle, it can be sup-pressed through the b-jet veto. However, for natural jetveto values around 30 GeV the top contamination re-mains larger than 10% of the W+W− cross section, anda complete suppression of the top contributions requiresa veto of the order of 1 GeV. Moreover, as pvetoT,bjet → 0,the (N)NLO cross section does not approach a constant,but, starting from pvetoT,bjet ∼ 10 GeV, it displays a loga-rithmic slope due to singularities associated with initialstate g → bb splittings. This sensitivity to the jet-vetoparameters represents a theoretical ambiguity at the sev-eral percent level, which is inherent in the definition oftop-free W+W− production based on a b-jet veto.

To circumvent this problem we will adopt an alterna-

10 7 Summary

Table 2: Expected and observed event yields for the ZZ selection. The uncertainties correspondto the statistical and systematic uncertainties added in quadrature.

Channel 4e 4µ 2e2µ 2`2tZZ 11.6 ± 1.4 20.3 ± 2.2 32.4 ± 3.5 6.5 ± 0.8Background 0.4 ± 0.2 0.4 ± 0.3 0.5 ± 0.4 5.6 ± 1.4Signal+background 12.0 ± 1.4 20.7 ± 2.2 32.9 ± 3.5 12.1 ± 1.6Data 14 19 38 13

tributions around the estimated central values. The resulting cross section is

s(pp ! ZZ) = 8.4 ± 1.0 (stat.) ± 0.7 (syst.) ± 0.4 (lum.)pb.

This is to be compared to the theoretical value of 7.7 ± 0.4 pb calculated with MCFM at NLOfor qq ! ZZ and LO for gg ! ZZ with MSTW08 PDF, and factorization and renormalizationscales set to the Z mass, for both lepton pairs in the mass range 60 < mZ < 120 GeV.

7 Summary

The W+W� and ZZ production cross sections have been measured in proton-proton collisionsat

ps = 8 TeV in the W+W� ! `0n`00n and ZZ ! 2`2`0 decay modes with ` = e, µ and `0(`00) =

e, µ, t. The data samples correspond to an integrated luminosity of 3.5 fb�1 for the W+W� and5.3 fb�1 for the ZZ measurements. The measured production cross sections s(pp ! W+W�) =69.9 ± 2.8 (stat.) ± 5.6 (syst.) ± 3.1 (lum.)pb and s(pp ! ZZ) = 8.4 ± 1.0 (stat.) ± 0.7 (syst.) ±0.4 (lum.)pb, for both Z bosons produced in the mass region 60 < mZ < 120 GeV, are consistentwith the standard model predictions. This is the first measurement of the diboson productioncross sections at

ps = 8 TeV.

Acknowledgements

We congratulate our colleagues in the CERN accelerator departments for the excellent perfor-mance of the LHC and thank the technical and administrative staffs at CERN and at other CMSinstitutes for their contributions to the success of the CMS effort. In addition, we gratefully ac-knowledge the computing centres and personnel of the Worldwide LHC Computing Grid fordelivering so effectively the computing infrastructure essential to our analyses. Finally, we ac-knowledge the enduring support for the construction and operation of the LHC and the CMSdetector provided by the following funding agencies: BMWF and FWF (Austria); FNRS andFWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS,MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER,SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA andCNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH(Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Re-public of Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico);MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Arme-nia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD(Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP-Center, IPST and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC(United Kingdom); DOE and NSF (USA).

- New NNLO cross-section is available [hep-ph:1408.5243],

in better agreement with data

For the future: moving to differential measurement




ETH Zurich

11/02/2011


H→W+W- dijet and resultsJHEP 01 (2014) 096

[GeV]llm50 100 150 200 250

Even

ts /

bin

0

5

10 data

WW→ H WW DY+jets top

(*)γ W W+jets

WZ+ZZ+VVV

= 125 GeVHm 2-jets, VBF tagµe

CMS (8 TeV)-119.4 fb

VBF tag

- 2jets: VBF-tag and VH tag use a fit to mll distribution

- Stewart-Tackmann procedure used for gluon fusion uncertainty

21

6.4 The two-jet VH tag 25

the distinct signature of having high momentum and large separation in pseudorapidity, hencesizeable invariant mass, with an absence of additional hadronic activity in the central rapidityregion due to the lack of color exchange between the parent quarks. By exploiting this specificsignature, VBF searches typically have a good signal-to-background ratio. In this analysis thesignal-to-background ratio approaches one after all the selection criteria are applied.

To select events with the characteristics of the VBF process, the two highest pT jets in the eventare required to have pseudorapidity separation of |Dhjj| > 3.5 and to form an invariant massmjj > 500 GeV. Events with an additional jet situated in the pseudorapidity range between thetwo leading jets are rejected. Both leptons are also required to be within the pseudorapidityregion defined by the two highest pT jets.

6.3.1 Analysis strategy

Given the small event yield for the 2-jet category with VBF tag with the currently availabledatasets, the signal extraction uses a template fit to a single kinematic variable with appropriately-sized bins. The dilepton mass, m``, has been chosen for its simple definition and discriminationpower, and also because the hadronic information is already extensively used in the event se-lection. The counting analysis is pursued for the same-flavor category, and also used as across-check of the shape-based approach for the different-flavor final state.

Since the fit to data uses only the m`` distribution, the events are preselected to satisfy mTsmaller than the Higgs boson mass of the given hypothesis. For Higgs boson mass hypothesesof 250 GeV and above, p`,max

T is required to be greater than 50 GeV. The m`` template has 14bins for the 8 TeV sample and 10 bins for the 7 TeV sample, covering the range from 12 GeV to600 GeV.

For the counting analysis, the same requirements as the 0-jet and 1-jet analyses are applied, assummarized in Table 4, except for the lower mT threshold which is kept at 30 GeV for all Higgsboson mass hypotheses. The results of the same-flavor counting analysis are combined withthe results of the different-flavor shape analysis to provide the result for this category.

6.3.2 Results

The data yields and the expected yields for the SM Higgs boson signal and various back-grounds in each of the lepton-flavor final states for the VBF analysis are listed in tables 9and 10, for several representative Higgs boson mass hypotheses. For a Higgs boson withmH = 125 GeV, a few signal events are expected to be observed with a signal-to-backgroundratio of about one. The contribution to the VBF selection from gluon fusion Higgs boson pro-duction after all selection requirements is approximately 20% of the total signal yield [87].

Figure 13 shows the comparison of m`` between the prediction and the data for a Higgs bo-son mass of 125 GeV after the selection for the shape-based analysis. The 95% CL observedand median expected upper limits on the production cross section of the H ! WW processare shown in Fig. 14. Limits are reported for both counting and shape-based analyses. Theobserved (expected) signal significance for the shape-based approach is 1.3 (2.1) standard devi-ations for a SM Higgs boson with mass of 125 GeV. The observed signal strength for this massis s/sSM = 0.62+0.58

�0.47. A summary of the results for mH = 125 GeV is shown in Table 11.

6.4 The two-jet VH tag

The analysis of the associated production of a SM Higgs boson with a W or a Z boson in thedilepton final state selects events with two centrally produced (|h| < 2.5) jets from the decay of

6.4 The two-jet VH tag 25

the distinct signature of having high momentum and large separation in pseudorapidity, hencesizeable invariant mass, with an absence of additional hadronic activity in the central rapidityregion due to the lack of color exchange between the parent quarks. By exploiting this specificsignature, VBF searches typically have a good signal-to-background ratio. In this analysis thesignal-to-background ratio approaches one after all the selection criteria are applied.

To select events with the characteristics of the VBF process, the two highest pT jets in the eventare required to have pseudorapidity separation of |Dhjj| > 3.5 and to form an invariant massmjj > 500 GeV. Events with an additional jet situated in the pseudorapidity range between thetwo leading jets are rejected. Both leptons are also required to be within the pseudorapidityregion defined by the two highest pT jets.

6.3.1 Analysis strategy

Given the small event yield for the 2-jet category with VBF tag with the currently availabledatasets, the signal extraction uses a template fit to a single kinematic variable with appropriately-sized bins. The dilepton mass, m``, has been chosen for its simple definition and discriminationpower, and also because the hadronic information is already extensively used in the event se-lection. The counting analysis is pursued for the same-flavor category, and also used as across-check of the shape-based approach for the different-flavor final state.

Since the fit to data uses only the m`` distribution, the events are preselected to satisfy mTsmaller than the Higgs boson mass of the given hypothesis. For Higgs boson mass hypothesesof 250 GeV and above, p`,max

T is required to be greater than 50 GeV. The m`` template has 14bins for the 8 TeV sample and 10 bins for the 7 TeV sample, covering the range from 12 GeV to600 GeV.

For the counting analysis, the same requirements as the 0-jet and 1-jet analyses are applied, assummarized in Table 4, except for the lower mT threshold which is kept at 30 GeV for all Higgsboson mass hypotheses. The results of the same-flavor counting analysis are combined withthe results of the different-flavor shape analysis to provide the result for this category.

6.3.2 Results

The data yields and the expected yields for the SM Higgs boson signal and various back-grounds in each of the lepton-flavor final states for the VBF analysis are listed in tables 9and 10, for several representative Higgs boson mass hypotheses. For a Higgs boson withmH = 125 GeV, a few signal events are expected to be observed with a signal-to-backgroundratio of about one. The contribution to the VBF selection from gluon fusion Higgs boson pro-duction after all selection requirements is approximately 20% of the total signal yield [87].

Figure 13 shows the comparison of m`` between the prediction and the data for a Higgs bo-son mass of 125 GeV after the selection for the shape-based analysis. The 95% CL observedand median expected upper limits on the production cross section of the H ! WW processare shown in Fig. 14. Limits are reported for both counting and shape-based analyses. Theobserved (expected) signal significance for the shape-based approach is 1.3 (2.1) standard devi-ations for a SM Higgs boson with mass of 125 GeV. The observed signal strength for this massis s/sSM = 0.62+0.58

�0.47. A summary of the results for mH = 125 GeV is shown in Table 11.

6.4 The two-jet VH tag

The analysis of the associated production of a SM Higgs boson with a W or a Z boson in thedilepton final state selects events with two centrally produced (|h| < 2.5) jets from the decay of

SMσ/σBest fit for -1 0 1 2 3

- 0.95 + 1.27 = 0.56SMσ/σ

, WH tagν 3l3

- 1.87 + 1.97 = 0.39SMσ/σ

+ 2-jets, VH tagν 2l2

- 0.46 + 0.57 = 0.60SMσ/σ

+ 2-jets, VBF tagν 2l2

- 0.20 + 0.22 = 0.74SMσ/σ

+ 0/1-jetν 2l2

- 0.18 + 0.20 = 0.72SMσ/σ

WW (all channels)→ H = 125.6 GeVHm

CMS (8 TeV)-1 (7 TeV) + 19.4 fb-14.9 fb

- Best fit signal strength μ=0.72+0.20-0.18 at 125.6 GeV

- Local significance: expected 5.8σ, observed 4.3σ- Trilepton final state also used:

WH→3l3ν, ZH→3lν+2jets




ETH Zurich

11/02/2011


Same sign WW scatteringarxiv:1410.6315 (submitted to PRL)

Signal definition: EWK+QCD with interferenceFiducial region:Mjj>500 GeV and dijet rapidity difference |Δηjj|>2.5

Backgrounds:- Jets faking electrons (non-prompt): estimated from loosely isolated leptons- WZ: estimated from data 3 leptons control region

Electroweak production QCD production

22

Electroweak WW production can help us understanding how Higgs is involved in unitarization.




ETH Zurich

11/02/2011


Same sign WW scatteringarxiv:1410.6315 (submitted to PRL)

23

Signal extraction:- Use dijet mass shape (4 bins x positive and

negative signs)- Significance: expected 3.1σ, observed 2.0σ

4

The normalization of the fake lepton processes has a 36% systematic uncertainty [17], whichhas two sources: the dependence on the sample composition, and the method used to estimateit. The WZ normalization uncertainty is 35%, and it is completely dominated by the amount ofevents in the trilepton control region.

A QCD scale systematic uncertainty of 50% on the VVV normalization is considered, and 5%on the signal normalization. A correlated PDF uncertainty of 6 � 8% on the normalization ofthe signal and WZ processes is included. All of the systematic uncertainties on normalizationsare described by log-normal distribution. A summary of all systematic uncertainties is shownin Table 2.

Table 2: Summary of all relative systematic uncertainties.

Source Signal WW DPS WZ Wrong sign VVV Non-promptLuminosity 2.6 2.6 - 2.6 2.6 -Lepton efficiency 3.6 3.6 3.6 3.6 3.6 -Momentum resolution 0.2 0.2 0.2 0.2 0.2 -b-tagging 2.0 2.0 - 2.0 2.0 -Emiss

T 1.0 1.0 1.0 1.0 1.0 -JES 3.0 3.0 3.0 3.0 3.0 -PDF 7.7 7.0 7.1 - - -QCD scales EWK 5.0 - - - - -QCD scales VVV - - - - 50.0 -WZ normalization - - 37.0 - - -Wrong sign normalization - - - 10.0 - -Nom-prompt normalization - - - - - 36.0Statistical uncertainty 2.0 57.0 15.0 55.0 18.0 19.0

The cross section is extracted for a fiducial dilepton same-sign signal region. An inclusive mea-surement would be dominated by non-EWK processes with the same final states. The fiducialregion is defined by p`T > 10 GeV, |h`| < 2.5, pj

T > 20 GeV, |h j| < 5.0, mjj > 300 GeVand |Dhjj| > 2.5. The measured cross sections are corrected to the acceptance in this regionusing the MADGRAPH MC generator, which is also used to estimate the predicted cross sec-tion. The MADGRAPH prediction of the same-sign W pair cross section is corrected by a k-factor estimated using VBFNLO [25–27]. The measured fiducial cross section is s(W±W± jj) =4.0+2.4

�2.0 (stat)+1.1�1.0 (syst) fb with an expectation of 5.8 ± 1.2 fb. In addition to the dilepton same-

sign signal region, a WZ ! `n`` control region is studied by requiring an additional leptonwith pT larger than 10 GeV. The measured fiducial cross section is s(WZjj) = 10.8± 4.0 (stat)±1.3 (syst) fb with an expectation of 14.4 ± 4.0 fb. The overall correction factor is 7.4% for thesame-sign W pair and 3.6% for the WZ fiducial cross section.

The observed (expected) significance is 2.0 s (3.1 s). If the 10% of the QCD W±W± componentis considered as background, and hence subtracted from the signal fraction, the observed (ex-pected) signal significance reduces to 1.9 s (2.9 s). In the absence of evidence for vector bosonscattering production, a 95% confidence level (CL) upper limit of 1.5 times the SM expectationwith an expected upper limit of 0.7 times the SM expectation is set.

Various extensions of the SM alter the couplings of vector bosons to each other. In Refer-ence [28] it is shown that there are nine independent C and P conserving dimension eighteffective operators modifying the quartic couplings between the weak gauge bosons. The vari-able m`` is found to be the most sensitive variable among those considered, e.g. m``, mlljj, andmjj. Figure 2 (left) shows the m`` distribution for three values of FT,0/L4 (where L is the newphysics scale), a coefficient of one of the nine effective operators, together with the sum of all

EWK / QCD contamination:- CMS defines signal as EWK+QCD (interference compatible with 0 within scale

uncertainty)

4












4












Also measure WZjj cross-section:




ETH Zurich

11/02/2011


Conclusions

24

- Diboson cross-sections: excess seems reduced by comparing to newly available NNLO cross-sections

- Accurate description of differential distributions needs NNLO differential or multijet ME+PS

- Higgs differential measurement at CMS is ongoing work, stay tuned...

- Higgs measurement rely on adequate MC for gluon fusion contamination in VBF

- WW scattering: first measurements performed. Needs more data for 5σ. Measuring interference with Higgs needs more data.

Thank you!

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26

BACK-UP SLIDES




ETH Zurich

11/02/2011


CMS detector

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!"#$#%%&'()*+',-./0123'4'!"5+#6+'*7'89,':;<< =

!"#$%&'&(')*

!"#$#%%&'()*+',-./0123'>'0,9-!':;<; =

+!,- ./.$0$12!,- ./.$0$3456*7(8&* ./.$0$941":);< ./.$0$94=

"&7<:*&>&;'$>7?&$@A'BA;$6*7(8&*$7((&C'7;(&$./.$0$941




ETH Zurich

11/02/2011


Luminosity conditions

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Analyses presented in this talk are using:- 5.1 fb-1 of 7 TeV data in 2011- Up to 20 fb-1 of 8 TeV data in 2012Pileup mean interaction ~21 in 2012 (~10 in 2011)




ETH Zurich

11/02/2011


CMS electromagnetic calorimeter(ECAL)

OutlineIntroduction

CMS projected sensitivity to H → γγ channelECAL Calibration

Electromagnetic energy deposits commissioningConclusions

CMS Electromagnetic calorimeter (ECAL)

The ECAL is made of PbWO4 scintillating crystals

Barrel (EB) : 36 “supermodules” of 1700 crystals each (coverage |η| < 1.48)

Endcaps (EE) : 268 “supercrystals” of 25 crystals each (coverage 1.48 < |η| < 3.0)

Additionnaly, a preshower (ES) detector made of silicon strip sensors is located infront of the endcap (coverage 1.65 < |η| < 2.6)

ECAL energy resolution (measured intest-beams) :

σ(E)

E=

ap

E(GeV )⊕

b

E(GeV )⊕ c

a = 2.8% : stochastic termb = 12% : noise termc = 0.3% : constant term

Nicolas Chanon Photon commissioning in CMS at√

s = 7 TeV 5 / 12

OutlineIntroduction

CMS projected sensitivity to H → γγ channelECAL Calibration

Electromagnetic energy deposits commissioningConclusions

CMS Electromagnetic calorimeter (ECAL)

The ECAL is made of PbWO4 scintillating crystals

Barrel (EB) : 36 “supermodules” of 1700 crystals each (coverage |η| < 1.48)

Endcaps (EE) : 268 “supercrystals” of 25 crystals each (coverage 1.48 < |η| < 3.0)

Additionnaly, a preshower (ES) detector made of silicon strip sensors is located infront of the endcap (coverage 1.65 < |η| < 2.6)

ECAL energy resolution (measured intest-beams) :

σ(E)

E=

ap

E(GeV )⊕

b

E(GeV )⊕ c

a = 2.8% : stochastic termb = 12% : noise termc = 0.3% : constant term

Nicolas Chanon Photon commissioning in CMS at√

s = 7 TeV 5 / 12

The ECAL is made of scintillating crystals of PbWO4 :-Barrel : 36 “supermodules” with 1700 crystals each (coverage |η|<1.48)-Endcaps : 268 “supercrystals” with 25 crystals each (coverage 1.48<|η|<3.0)Furthermore, a preshower made of silicon strip sensors is located in front of the endcaps (1.65<|η|<2.6)

Energy resolution (measured in electron test beam) :

a = 2.8% stochastic termb = 12% noise termc = 0.3% constant tern




ETH Zurich

11/02/2011


Diphoton cross-section at 7 TeVSMP-13-001, 4.7fb-1 at 7 TeV

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

| (pb

)* θ

/d|c

osσd

10

-1data 2011, L = 5.0 fb

SHERPA

RESBOS

= 7 TeVsCMS Preliminary

0 0.2 0.4 0.6 0.8 1data

/SH

ERPA

012

34

|*θ|cos0 0.2 0.4 0.6 0.8 1da

ta/R

ESBO

S

012

34

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1| (

pb)

* θ/d

|cos

σd

10

-1data 2011, L = 5.0 fb

DIPHOX+GAMMA2MC

NNLO γ2

= 7 TeVsCMS Preliminary

0 0.2 0.4 0.6 0.8 1

data

/DIP

HO

X

012

34

|*θ|cos0 0.2 0.4 0.6 0.8 1

NN

LOγ

data

/2

012

34




ETH Zurich

11/02/2011


Zγ→llγ cross-sectionhttps://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP13014

Kinematical range: - Leptons Mll>50 GeV, pT,l>20 GeV, photons |ηγ|<2.5, ET,γ>15 GeV, ΔR(γ,l)>0.7

(selects ISR)Two methods are combined to estimate jets faking photons background: - Particle-flow photon isolation template - η width of the energy deposit (“σiηiη”)- Sideband regions tuned to minimize bias in MC

NEW

31ηiηiσ

0.005 0.01 0.015 0.02 0.025 0.03

Even

ts

0

200

400

600

800

1000

1200

1400

1600 Data

p-value: 50.0% < 25 GeV

TFit: EB, 20 GeV < p

80±Signal: 3775

39±Background: 943

(8 TeV)-1 channel, L = 19.5 fbγµµCMS Preliminary

(GeV),nfpγI0 5 10 15 20 25

Even

ts

0

100

200

300

400

500

600

700

800 Data

p-value: 46.0% < 25 GeV

TFit: EB, 20 GeV < p

92±Signal: 4327

75±Background: 1485

(8 TeV)-1 channel, L = 19.5 fbγµµCMS Preliminary

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP13014





ETH Zurich

11/02/2011



Inclusive cross section measured vs photon pT- For the first time comparison with NNLO [Grazzini, Kallweit, Rathlev, Torre, hep-

ph:1309.7000]: good agreement- Kinematical range: Leptons Mll>50 GeV, pT,l>20 GeV, |ηl|<2.5, photons |ηγ|<2.5,

ET,γ>15 GeV, ΔR(γ,l)>0.7

(GeV)γ

Tp20 30 40 50 210 210×2

)γ T

/dp

NNLO

incl.

σ) /

(dγ T

/dp

incl.

σ(d

0.6

0.8

1

1.2

1.4

1.6

1.8

2γ, eeγµµData combined:

NNLO

MCFM (NLO)

SHERPA (LO) up to 2 partons, stat. unc. only

(8 TeV)-1L = 19.5 fbCMS Preliminary

(GeV)γ

Tp20 30 40 50 210 210×2

(fb/

GeV

)γ T

/dp

incl.

σd

-110

1

10

210

γ, eeγµµData combined: MCFM (NLO)NNLOSHERPA (LO) up to 2 partons, stat. unc. only


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Ratio

NEW






ETH Zurich

11/02/2011



Exclusive cross-section with jet veto:- Comparison with MCFM (NLO) and Sherpa with jet-veto: good agreement also

with NLO because of softer phase-space- No jet with pT>30 GeV in |ηj|<2.4

(GeV)γ

Tp20 30 40 50 210 210×2

)γ T

/dp

MCF

Mex

cl.σ

) / (d

γ T/d

pex

cl.σ

(d

0.6

0.8

1

1.2

1.4

1.6

1.8

2γ, eeγµµData combined:

MCFM (NLO)



(GeV)γ

Tp20 30 40 50 210 210×2

(fb/

GeV

)γ T

/dp

excl.

σd

-210

-110

1

10

210

γ, eeγµµData combined:

MCFM (NLO)



Ratio

33

NEW






ETH Zurich

11/02/2011



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aTGC measurement:- Limits set using photon pT- Limits on ZZγ, Zγγ vertices- Improvement by a factor 2.5-3 over the previous 7 TeV measurement

(GeV)γ

Tp

100 150 200 250 300 350 400 450 500

Even

ts /

4 G

eV

-110

1

10

210DataStandard Model

= 0.001Z4 = 0, hZ

3h = 0Z

4 = 0.03, hZ3h

= 0.0016Z4 = 0.06, hZ

3h

(8 TeV)-1 channel, 19.5 fbγµµ

SM p-value: 0.37

CMS Preliminary

Z3h

-0.01 -0.005 0 0.005 0.01

Z 4h

-0.1-0.08-0.06-0.04-0.02

00.020.040.060.08

0.1-310×

Excl

usio

n pr

obab

ility

0.10.20.30.40.50.60.70.80.91

(8 TeV)-1 channels, 19.5 fbγ and eeγµµ

CMS PreliminaryγZZData best fit Data CL = 95% MC CL = 68%MC CL = 95%MC CL = 99%

γ3h

-0.01 -0.005 0 0.005 0.01

γ 4h

-0.1-0.08-0.06-0.04-0.02

00.020.040.060.08

0.1-310×

Excl

usio

n pr

obab

ility

0.10.20.30.40.50.60.70.80.91

(8 TeV)-1 channels, 19.5 fbγ and eeγµµ

CMS PreliminaryγγZData best fit Data CL = 95% MC CL = 68%MC CL = 95%MC CL = 99%

NEW






ETH Zurich

11/02/2011



35

Behavior using a form factor and unitarity bounds- The non-unitarized limit can be recovered with a infinity form factor- Unitarity bound (computed with VBFNLO website) crossed for a form factor of

around 6 TeV (h3Z) or 3.5 TeV (h4Z)- Below, the measurement probes aTGC in the unitarity region

(TeV)Λ2 3 4 5 6 7

Z 3h

-0.01

-0.005

0

0.005

0.01

0.015

allowed

(8 TeV)-1 channels, L = 19.5 fbγ and eeγµµ

CMS Preliminary DataMC expectedσ2±σ1±

Unitarity Bounds

(TeV)Λ2 3 4 5 6 7

Z 4h

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-310×

allowed

(8 TeV)-1 channels, L = 19.5 fbγ and eeγµµ

CMS Preliminary DataMC expectedσ2±σ1±

Unitarity Bounds

NEW



ETH Zu¨rich γγ H Nicolas Chanon Modeling of Diboson+jets ......γγ Zγ WW ZZ Fig. 2: Higgs...

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