Measurements of Higgs boson production and properties in the WW decay channel with both W’s decaying into electrons or muons plus neutrino using the CMS detector

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Measurements of Higgs boson production and properties in the WW decay channel with both W’s

decaying into electrons or muons plus neutrino using the CMS detector

P. Govoni, on behalf of the CMS Collaboration Milano-Bicocca University and INFN

! JHEP 01 (2014) 096

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the fully leptonic H → WW →lvlv final state

• H → vector bosons: early discovery channels

• VVH couplings originate from EWSB: provide the longitudinal WL and ZL

components to the vector bosons

• access the Higgs boson spin from the vector bosons decay angles

• H → WW largest branching ratio among them

2

• main backgrounds are non-resonant WW, tt pairs production and Drell-Yan (with same-flavour leptons)

• instrumental bkg: sub-leading, but with large uncertainty

• divide the final state study into same-flavour and different-flavour categories

• 2 oppositely charged isolated leptons (electrons and muons) with minimum pT of 20,10 GeV

• moderate MET: at least 20 GeV

• jets counted with pT > 30 GeV, veto on the presence of b-jets

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the Higgs boson production

3

gluon fusion!

• main production channel

• separated into 0 and 1 jet bins

vector boson fusion (VBF)!

• first sub-leading production channel

• VVH coupling in

production and decay

H-strahlung (VH)!

• lower cross-section

• search for the additional vector boson

250 evt 10 evt 14 evt

V = W → lv V = W → jj V = Z → l⁺l^-

yesterday’s L. Bianchini’s talk covered the ttH production expected signal events

after all selections

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the main selection variables

4

[GeV]

l

ml

0 100 200 300

Events / 10 GeV

0 500 1000

data

→ WW H W+jets WZ+ZZ+VVV

top DY+jets WW

= 125 GeV mH

0-jet eµ

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

• key variables: transverse mass mT, di-lepton mass mll and Δφll

• additional handles from the exclusive production modes!

• VBF: two additional jets with large Δη and invariant mass

• VH: the presence of an additional vector boson

m

²_T

= 2p

^``_T

E

_T^miss

1 cos (``, E ~

_T^miss

)

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background control

5

[GeV]

l

ml

0 50 100 150 200

Events / bin

0 50 100 150

200 _data

→ WW H

γ(*)

W W+jets

WZ+ZZ+VVV top

DY+jets WW

= 125 GeV mH

0-jet same-sign eµ

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

[GeV]

mT

100 150 200 250

Events / bin

0 500

1000 ^data_H_→_WW

γ(*)

W W+jets

WZ+ZZ+VVV top

DY+jets WW

= 125 GeV mH

1-jet top-tagged, eµ

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

• no H peak: low resolution on mH, data-driven background control needed

• normalisation and shape modelling are cross-checked in control regions

same-charge leptons pairs in the 0-jet bin

top-enriched events   in the 1-jet bin

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the analysis strategy in 0 and 1 jet bins

• eμ: 2D template fit to extract signal and background: (mT, mll) plane!

• ee/μμ: cut-based limit on the most sensitive variables

6

pre-fit distributions for signal and background models (the red box is the cut-based phase space)

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the result of the fit

• post-fit distributions, overlapped to data

• S/(S+B) reweighting along mll (the other variable in the 2D plane)

7

[GeV]

mT

50 100 150 200 250

S/(S+B) weighted events / bin

0 500 1000

data

→ WW H

γ(*)

W W+jets

WZ+ZZ+VVV top

DY+jets WW

= 125 GeV mH

0/1-jet eµ

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

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exclusive analysis: vector boson fusion

• second production channel (10% of the total)

• additional selection handles: S/B ~ 1:1!

• Δηjj > 3.5 and mjj > 500 GeV,

• central activity veto, final state leptons between the tag jets

8

[GeV]

mT

0 100 200

Events / bin

0 10 20 30

data

→ WW H

γ(*)

W W+jets

WZ+ZZ+VVV top

DY+jets WW

= 125 GeV mH

dilepton + 2-jets top-tagged

CMS 19.4 fb^-1 (8 TeV)

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exclusion limit and significance

9

Higgs boson mass [GeV]

SMσ/σ95% CL limit on

10-1

1 10 102

110 200 300 400 500 600

CMS

WW (all channels) H →

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

4.9 fb-1

Observed

Median expected 1σ Expected ±

2σ Expected ±

observed 1.1 expected 0.3

the exclusion limit

Significance

0 5 10 15 20 25

Expected Observed

110 200 300 400 500 600

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

observed 4.3 σ expected 5.8 σ

/

_SM

= 0.72

^+0.20_0.18

= 0.72

^+0.12_0.12

(stat.)

^+0.12_0.10

(th. syst)

^+0.10_0.10

(exp. syst)

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the significance

from here onwards: m

H

= 125.6 GeV

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additional tests

10

10-1

1 10 102

110 200 300 400 500 600

CMS

SM H (125.6 GeV) as background WW (all channels)

H →

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

4.9 fb-1

Observed

Median expected 1σ Expected ±

2σ Expected ±

the limit with 125 GeV SM Higgs as bkg: no signs of

additional resonances results are consistent

among different categories

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Higgs boson couplings

11

κV

0 0.5 1 1.5

fκ

0 0.5 1 1.5

2

Observed

68% CL Observed 95% CL Observed Exp. for SM H 68% CL Expected 95% CL Expected

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

vary the Higgs couplings wrt the SM with multiplicative modifiers k

⇥ BR(X ! H ! WW) = ²_i ²_V

²_H ^SM ⇥ BR_SM(X ! H ! WW)

full integration in the SM fit in M. Chen talk

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tensor structure measurements

12

• extract all the possible information on the Higgs spin and parity, starting from the eμ 2D template fit analysis baseline

spin 0!

• put limits on the XS fractions of non-SM components in the decay amplitude

spin 1, 2!

• different pure spin hypotheses are compared to the SM case

see E. Di Marco presentation

CMS PAS HIG-14-012

- 1 + 1 b+ 2→gg h- 2→gg h+ 2→gg h2+ 2→gg h3+ 2→gg h6+ 2→gg h7+ 2→gg h9- 2→gg h10- 2→gg b+ 2→qq h- 2→qq h+ 2→qq h2+ 2→qq h3+ 2→qq h6+ 2→qq h7+ 2→qq h9- 2→qq h10- 2→qq

)+ 0 /L P J-2 ln(L

-30 -20 -10 0 10 20 30 40 50

60 CMS (preliminary) 19.4 fb^-1 (8 TeV)

2l2ν WW → CMS data Median expected

1σ

+±

0 J^P± 1σ

2σ

+±

0 J^P± 2σ

3σ

+±

0 J^P± 3σ

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conclusions

• H → WW →lvlv is one of the channels with the largest yield at the Higgs boson mass peak

• small uncertainty on the signal strength

• access to exclusive production channels

• with the full 7 and 8 TeV dataset a signal with an observed significance  of 4.3 σ has been observed:

!

• observed significance of 1.3 σ in VBF (expected: 2.1 σ)

• a wide investigation of the H tensor structure does not show any deviations from the SM

13

/

_SM

= 0.72

^+0.20_0.18

= 0.72

^+0.12_0.12

(stat.)

^+0.12_0.10

(th. syst)

^+0.10_0.10

(exp. syst)

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(at mH =125.6 GeV)

high mass analysis in tomorrow’s O. Gonzalez Lopez talk

4.3 σ observed (5.8 σ expected)

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backup slides

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• a few events expected (over all the final states)

• additional handles from the presence of the final state vector boson

• worse S/B ratio than vbf

• several final states for the vector boson addressed

exclusive analysis: VH

15

l-

l+

∆ R

0 1 2 3 4

Events / 0.8

10-1

1 10

102 _data VH

γ(*)

W

non-prompt ZZ

WZ

= 125 GeV mH

SSSF 3l3ν

CMS 19.4 fb^-1 (8 TeV)

VH, V → lv, H → lvlv

110 120 130 140 150 160 170 180 190 200

1 10 102

CMS

(shape-based analysis)→ 3l3ν WH

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

4.9 fb-1

Observed Median expected

1σ Expected ±

2σ Expected ±

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Higgs boson mass

16

[GeV]

mH

120 140 160

SMσ/σ

0 1 2 3

0 5 10 15 20

Observed

68% CL Observed 95% CL Observed

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

0/1-jet eµ

m

_H

= 125.5

^+3.6_3.8

GeV m

_H

= 128.2

^+6.6_5.3

GeV

[GeV]

mH

110 120 130 140

lnL∆-2

0 2 4 6 8 10

BR)SM

× BR = (σ

× 0/1-jet, σ eµ

CMS 4.9 fb^-1 (7 TeV) + 19.4 fb^-1 (8 TeV)

2 σ

1 σ

/

_SM

= 1

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the razor variable

17

[GeV]

mR

100 200 300 400 500

probability density

0 0.02 0.04 0.06 0.08 0.1

WW top DY+jets W+jets WZ+ZZ

γ(*)

W+

=125 GeV WW, mH

H→

CMS Simulation (8 TeV)

0-jet eµ

[GeV]

mR

50 100 150 200 250

probability density

0 0.01 0.02 0.03

0.04 ^m^H^{=115 GeV}

=125 GeV mH

=135 GeV mH

=145 GeV mH

CMS Simulation (8 TeV)

0-jet eµ