at the LHC and Beyond...b¯b⌧ + ⌧ b¯bWW ⇤ • larger cross section • large bkg • may be...

Double Higgs production at the LHC and Beyond

Giuliano PanicoIFAE Barcelona

‘Higgs Hunting 2016’Paris – 1/9/2016

HH production processes

10-3

10-2

10-1

100

101

102

103

104

8 13 14 25 33 50 75 100

σN

LO[fb

]

√s[TeV]

HH production at pp colliders at NLO in QCDMH=125 GeV, MSTW2008 NLO pdf (68%cl)

pp→HH (EFT loop-improved)

pp→HHjj (VBF)

pp→ttHH pp→WHH

pp→tjHH

pp→ZHH

MadGraph5_aMC@NLO

Several production channelsbut tiny cross section in the SM

✦ leading: gluon fusion

✦ potentially interesting:

• vector boson fusion (VBF)

• ttHH production

g

g

h

h

t

g

g

h

h

t

t

q

q

h

h

�VBF14TeV = 1.94+2.3%

�2.6%(scale) fb

�ttHH14TeV = 0.949+1.7%

�4.5%(scale) fb

�GF14TeV ' 40 fb

L = �1

2m2

hh2 � �3

m2h

2vh3 � �4

m2h

8v2h4

Why double Higgs?Obvious answer: directly accessing the Higgs potential!

10-1

100

101

102

-4 -3 -2 -1 0 1 2 3 4σ

(N)L

O[fb

]λ/λSM

pp→HH (EFT loop-improved)pp→HHjj (VBF)

pp→ttHH

pp→WHH

pp→ZHH pp→tjHH

HH production at 14 TeV LHC at (N)LO in QCDMH=125 GeV, MSTW2008 (N)LO pdf (68%cl)

MadGraph5_aMC@NLO

g

g h

h

th

g

g h

h

t

Significant dependence in the production rates

✦ in gluon fusion destructive interference

�3

Why double Higgs?

Less obvious answers:

✦ extract non-linear couplings not accessible in single Higgs

✦ alternative measurement of single-Higgs vertices

✦ probe the strength of EWSB dynamicsat high energy E � mh

✦ explore extended Higgs sectors

Non resonan

t

Resonan

t

gg!

hh

pp!

hh+jj

pp!

H!

hh

Non-resonant processes The Gluon Fusion channel

The Higgs effective Lagrangian

g

g h

h

t

g

g h

h

h

g

g h

h

g

g h

h

th

g

g h

h

t

Several vertices contribute to double Higgs production in GF

L � �mttt

✓cth

v+ c2t

h2

2v2

◆� �3

m2h

2vh3 +

g2s4⇡2

✓cg

h

v+ c2g

h2

2v2

◆Gµ⌫G

µ⌫

✦ modifications of the single Higgs couplings can affect HH production (eg. )tth

Modified single Higgs couplings

g

g h

h

t

g

g h

h

h

g

g h

h

g

g h

h

th

g

g h

h

t


L � �mttt

✓cth

v+ c2t

h2

2v2

◆� �3

m2h

2vh3 +

g2s4⇡2

✓cg

h

v+ c2g

h2

2v2

◆Gµ⌫G

µ⌫

Non-linear Higgs couplings

g

g h

h

t

g

g h

h

h

g

g h

h

g

g h

h

th

g

g h

h

t


L � �mttt

✓cth

v+ c2t

h2

2v2

◆� �3

m2h

2vh3 +

g2s4⇡2

✓cg

h

v+ c2g

h2

2v2

◆Gµ⌫G

µ⌫

✦ modifications of the single Higgs couplings can affect HH production (eg. )tth

✦ some vertices can be probed independently only in HH processes (eg. , )h2Gµ⌫G

µ⌫tthh

Parametrization for a doublet Higgs

If the Higgs is part of an SU(2) doublet the number of independent operators is reduced

L � cH2v2

[@µ(H†H)]2 +

cuv2

yuH†HqLH

cuR � c6v2

m2h

2v2(H†H)3 +

cgm2

w

g2sH†HGµ⌫G

µ⌫

Buchmuller and Wyler ; …Giudice et al.; Grzadkowski et al.

c3 ≃ 1−3

2cH + c6 cg = c2g = cg

!

4π

α2

"

c2t ≃ −

1

2(cH + 3cu)ct ≃ 1−

cH

2− cu

✦ requires an additional expansion in Higgs powers

Dependence on Higgs couplings

c2 t=D

c3=1+D

ct=1+DLHC 14 TeV

SM

-1.0 -0.5 0.0 0.5 1.0

0.10.20.51.02.05.010.020.0

D

sHppÆ

hhLêsH

ppÆhhL SM

�3

✦ Shape analysis could disentangle the various interactions

✦ mild dependence on �3

• effects mostly at threshold

✦ strong dependence on topcouplings and ct c2t

• affect peak and tail of mhh

In many BSM scenarios modifications to all Higgs couplingsarise simultaneously and have comparable size

Behaviour of amplitudes

✦ Different behaviour at high energy

Double Higgs production via gluon fusion

g

g h

h

t

g

g h

h

th

g

g h

h

t

⇠ c

2

t

⇥ const. ⇠ c

t

c

3

⇥m

2

h

s

log2

m

2

t

s

!⇠ c

2t

⇥ log2

m

2

t

s

!

g

g h

h

h

g

g h

h

⇠ c

g

c

3

↵

s

4⇡

⇥ const. ⇠ c

2g

↵

s

4⇡

s

v

2

v Di↵erent behaviour at high energyp

s = mhh

� 2mh

v Dependence on Higgs trilinear suppressed at high energy

I events at threshold more sensitive to Higgs trilinear, events at largem

hh

more important to determine the other operators

✦ Dependence on Higgs trilinear suppressed in the tail• events at threshold more sensitive to Higgs trilinear,

events at large more important to determine the other operatorsmhh

ps = mhh � 2mh

�SM14TeV ' 39.5 fb

Final statesGF is the hh production channel with highest cross section

Many final states with reasonable number of events at HL-LHC

• small number of events• clean final state (small bkg)• can access total cross section

✦ golden channel:

✦ other modes: , , bbbb

bb��

bbWW ⇤bb⌧+⌧�

• larger cross section• large bkg• may be useful to probe tail of distribution (boosted jet techniques)

decay channel BR events (3 ab�1)

bbbb 33% 40000

bbWW ⇤ 25% 31000

bb⌧+⌧� 7.3% 8900

ZZbb 3.1% 3800

WW ⇤⌧+⌧� 2.7% 3300

ZZWW ⇤ 1.1% 1300

bb�� 0.26% 320

Full LO: Glover, van der Bij ’88Full NLO: Borowka, Greiner et al. ‘16Approximate NNLO + NNLL: De Florian, Mazzitelli ’13, ’15; Grigo, Melnikov, Steinauser ’14; Grigo, Hoff, Steinauser ’15; Shao, Li, Wang ’13

Gluon Fusion at 100 TeV

(GeV)hhm0 500 1000 1500 2000 2500 3000 3500 4000

Nor

mal

ized

rate

-610

-510

-410

-310

-210

-110

✦ huge increase in cross section (~40 times 14 TeV)

�SM100TeV ' 1400 fb

✦ similar shape at threshold andaround the peak

✦ significant increase in the high tailmhh

14 TeV

100 TeV

•

•

•

•

• comprehensive study at 100 TeV:

(Partial) List of theoretical analyseshh ! bb��

hh ! bbbb

hh ! bb⌧+⌧�

hh ! bbWW ⇤

Baur, Plehn, Rainwater hep-ph/0310056Baglio, Djouadi, Grober, Mullheitner, Quevillon et al. 1212.5581Yao 1308.6302Barger, Everett, Jackson, Shaughnessy 1311.2931Azatov, Contino, Panico, Son 1502.00539Kling, Plehn, Schichtel 1607.07441

Baur, Plehn, Rainwater hep-ph/0304015Dolan, Englert, Spannowsky 1206.5001Baglio, Djouadi, Grober, Mullheitner, Quevillon et al. 1212.5581Barr, Dolan, Englert, Spannowsky 1309.6318Goertz, Papaefstathiou, Yang, Zurita 1410.3471

Dolan, Englert, Spannowsky 1206.5001Baglio, Djouadi, Grober, Mullheitner, Quevillon et al. 1212.5581Papaefstathiou, Yang, Zurita 1209.1489

de Lima, Papaefstathiou, Spannowsky 1404.7139

Contino et al., “Physics at a 100 TeV pp collider : Higgs and EW symmetry breaking studies”,1606.09408

The Golden Channel bb��

Tiny cross section: �SM(HH ! bb��) ' 0.1 fb

The Higgs trilinear at HL-LHC

Main backgrounds:re

sona

ntno

n re

sona

nt

events after selection (CMS analysis FTR-15-002)

bbj�

ZHttH

bbH

bb��

jj��

bbjj

tt�

3.41.60.8

10.4

2.1

6.3

1.1

1.2

24.8total

signal events: 9.0

Only determinationof is possibleO(1)�3

see also ATLAS: PHYS-PUB-2014-019, PHYS-PUB-2015-46

✦ Some improvement possible with multivariate techniques Kling, Plehn, Schichten ‘16

�

�SM2 [0.4, 1.7] at 68% CL

total

Prospects at 100 TeVSizeable cross section: Main backgrounds:

res.

non

res.

events after selection with (Contino et al. 1606.09408)

bbj�

ttH

bb��

jj��signal events:

see also Kling, Plehn, Schichten ‘16

�SM(HH ! bb��) ' 3.6 fb

✦ Good precision on SM cross section: at 68% CL✦ Good determination of Higgs trilinear: at 68% CL

9300

3250

3250

2000

17800

7400

20 ab�1

⇠ 4.5%

⇠ 2%

Fit to non-linear Higgs couplings

-0.5 0.0 0.5 1.0-0.15

-0.10

-0.05

0.00

0.05

0.10

c2 t

c2 g

-1.0 -0.5 0.0 0.5 1.0-10

-5

0

5

10

c2 t

c3

FCC100

LHC14 LHC14

HL-LHC

HL-LHC

FCC100

Determination of , andc3 c2gc2t

✦ Correlation between Higgs trilinear and top couplings✦ Good precision on contact interactions to top and gluons

benchmark scenarios: LHC14

HL-LHCFCC100

ps = 14 TeV , L = 300 fb�1

ps = 14 TeV , L = 3 ab�1

ps = 100 TeV , L = 3 ab�1

Exclusive vs inclusive analysis

-1.0 -0.5 0.0 0.5 1.0

-4

-2

0

2

4

6

8

10

c2 t

c3

s =100TeV L=3ab-1

Exclusive analysis is crucial at FCC100

categorymhh [GeV]

1 2 3 4 5 6

250 - 400 400 - 550 550 - 700 700 - 850 850 - 1000 1000 -

exclusive

inclusive

¯

-0.4 -0.2 0.0 0.2 0.4

-2

0

2

4

c2 t

c3

s =100TeV L=3ab-1

cat. 1,2

cat. 3,4

cat. 5,6

Operators in the Higgs doublet basis

¯

-0.5 0.0 0.5-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

cu

c gâH4pêa 2L

LHC s =14TeV L=3ab-1

double Higgs

single Higgs(excl. tth)

only tth

¯

-0.4 -0.2 0.0 0.2 0.4

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

cu

c gâH4pêa 2L

s =100TeV L=3ab-1

✦ Double Higgs measurement can resolve the degeneracy in

✦ At FCC100 can be competitive with for the determination of the top Yukawa (if precision from single Higgs similar to the LHC one)

tthcu

cg

orange region: single Higgs incl.blue region: single + double Higgs

tth

Non-resonant processes The Vector Boson Fusion channel

results from Contino, Rojo, work in progress (courtesy of R. Contino)

Testing the strength of EWSB

VBF can test perturbative unitarization q

q

h

h

+ ⇠ s

v2(c2V � c2V )

⇠ m2h

v3�3cV

L �✓m2

WW 2µ +

m2Z

2Z2µ

◆✓1 + 2cV

h

v+ c2V

h2

v2

◆

✦ Cross section grows at high if the couplings are modified(in the SM )

mhhcV = c2V = 1

500 1000 1500 2000 2500 3000

1

1x101

1x102

1x103

1x104

1x105

1x106

1x107

LL → hh (MHCM5)LL → hh (MHCM4)TT → hhLT → hh

√s [GeV]

σ tot (

W+W

- →h

h)

[fb

]

a2-b=0.5

a2-b=1

SM

Contino et al. 1002.1011

Higgs couplings from VBF

�15 �10 �5 0 5 10 150.00

0.02

0.04

0.06

0.08

0.10

c3�1�0.6 �0.4 �0.2 0.0 0.2 0.4 0.60

1

2

3

4

c2 V�1

68% probability intervals on :

m(hh) [GeV]

14TeV 250� 500 500� 750 750� 1000 1000� 1500 > 1500

hh!4b [SM] 6.6 4.1 1.6 0.68 0.18

4b2j 9.8⇥103 557 203 101 15

m(hh) [GeV]

100TeV 250� 1000 1000� 2500 2500� 3500 3500� 5000 > 5000

hh!4b [SM] 413 144 10 2.1 1.1

4b2j 5.9⇥105 3.4⇥104 6.2⇥103 2.3⇥103 2.3⇥103

c3=1cV =1

c2V =1

�c2V ⌘ c2V �1 LHC14 HL-LHC FCC100

[�0.18, 0.22] [�0.08, 0.12] [�0.01, 0.03]

23

Number of events with 3ab-1 after cuts

Prob

abilit

y de

nsity

Prob

abilit

y de

nsity

FCC100

HL-LHC

LHC14

FCC100

HL-LHC

LHC14

cV =1

(uncertainties included: 50% systematic on background, 10% on )BR(hh ! 4b)

PRELIMINARY

�15 �10 �5 0 5 10 150.00

0.02

0.04

0.06

0.08

0.10

c3�1�0.6 �0.4 �0.2 0.0 0.2 0.4 0.60

1

2

3

4

c2 V�1

68% probability intervals on :

m(hh) [GeV]

14TeV 250� 500 500� 750 750� 1000 1000� 1500 > 1500

hh!4b [SM] 6.6 4.1 1.6 0.68 0.18

4b2j 9.8⇥103 557 203 101 15

m(hh) [GeV]

100TeV 250� 1000 1000� 2500 2500� 3500 3500� 5000 > 5000

hh!4b [SM] 413 144 10 2.1 1.1

4b2j 5.9⇥105 3.4⇥104 6.2⇥103 2.3⇥103 2.3⇥103

c3=1cV =1

c2V =1

�c2V ⌘ c2V �1 LHC14 HL-LHC FCC100

[�0.18, 0.22] [�0.08, 0.12] [�0.01, 0.03]

23

Number of events with 3ab-1 after cuts

Prob

abilit

y de

nsity

Prob

abilit

y de

nsity

FCC100

HL-LHC

LHC14

FCC100

HL-LHC

LHC14

cV =1

(uncertainties included: 50% systematic on background, 10% on )BR(hh ! 4b)

PRELIMINARY

Best channel: hh ! 4b

✦ huge background, sensitive only if deviations much larger than SM✦ poor precision on Higgs trilinear (not competitive with GF)✦ FCC100 can provide good bounds on �c2V ⌘ c2V � 1

68% probability intervals on �c2V

LHC14 HL-LHC FCC100

[-0.18, 0.22] [-0.08, 0.12] [-0.01, 0.03]

Resonant processes Scalar Singlet production

g�ffgSMhff

=g�V V

gSMhV V

= sin � =

M2

hh �m2h

m2� �m2

h

!1/2

Additional scalar singlet

Extensions of the Higgs sector are quite common in BSM scenarios

✦ Couplings controlled by the mixing with the Higgs

✦ Main decay channels

BR(� ! hh) = BR(� ! ZZ) =

1

2

BR(� ! WW ) =

1

4

, for m� � mW

Additional singlet is often present (eg. NMSSM, Twin Higgs, …)results taken from Buttazzo, Sala, Tesi, 1505.05488see also references therein

g�hh

couplings to SM

coupling to the Higgs

�

Direct searches

Direct searches can exploit the VV and hh channels

500 1000 1500 2000 2500 3000 3500

0.1

1

10

100

1000

mf @GeVD

sppÆf+

XBRfÆhh@fbD

13 TeV, 100 fb-1

14 TeV, 300 fb-1

14 TeV, 3000 fb-1

CMS observed, 8 TeV pp Æ f Æ hhH4bLMSTW2008

500 1000 1500 2000 2500 3000 3500

0.1

1

10

100

1000

mf @GeVD

sppÆf+

XBRfÆZZ@fbD

13 TeV, 100 fb-1

14 TeV, 300 fb-1

14 TeV, 3000 fb-1

CMS observed, 7+8 TeV

pp Æ f Æ VVMSTW2008

Current experimental analyses in the channel

8 TeV ATLAS CONF-2014-005 CMS 1503.04114

13 TeV ATLAS CONF-2016-049

� ! hh(4b)

Buttazzo, Sala, Tesi, ‘15 Buttazzo, Sala, Tesi, ‘15

Reach of direct searches

��

��

��

��

��

��

��

��

��

�ϕ [��]

��[��

]ϕ → ��ϕ → ��(��)

�� = -��

��

��

��

��

��

��

��

��

��

�ϕ [��]

��[��

]

ϕ → ��ϕ → ��(��)ϕ → ��(��γ)

In some regions of the parameter space, the channel give the best reach

LHC13

LHC14

HL-LHC

HL-LHCFCC33

FCC100

Current

� ! hh(4b)

Buttazzo, Sala, Tesi, ‘15

��

��

��

��

��

��

��

��

��

��

��

�ϕ [��]

��[��

]

Δμ/μ��ϕ → ��

��[ϕ→��] = ��

��

��

��

-��

-�

�

�

��

��

��

��

��

��

��

��

��

�ϕ [��]�

��[��

]

Δμ/μ��

�� = -��

Deviations in the Higgs couplings

LHC13LHC14

HL-LHC

CurrentButtazzo, Sala, Tesi, ‘15

Higgs couplings

Higgs trilinear

✦ Direct searches can be competitive with indirect constraints from Higgs couplings deviations

✦ Sizeable deviations in the Higgs trilinear coupling expected

Conclusions

ConclusionsDouble Higgs production can give access to a rich landscape of phenomena both in the SM and Beyond

✦ Non-resonant processes• probe Higgs potential (in particular Higgs trilinear)• access non-linear Higgs couplings• test the strength of EWSB at high energy• small cross section:

limited precision at LHC good prospects at future high energy colliders (eg. FCC100)

✦ Resonant processes• test extended Higgs sectors• good reach possible at HL-LHC

Backup

Non-resonant processes Double Higgs at e+e– Colliders

Main production channels

25

Measurement of Higgs couplings and self-coupling at the ILC Junping TIAN

Z

H

ZH

He+

e�Z

H

ZH

e+

e�Z

H

ZH

e+

e�Z

H

ZH

e+

e�+ + +

Background diagramsSignal diagram

(a)

+ + +


(b)

H

HH

�

��e+

e�

H

H�

��e+

e�

H

H�

��e+

e�

H

H�

e+

e�

��

Center of Mass Energy / GeV400 600 800 1000 1200 1400

Cro

ss S

ect

ion / fb

0

0.1

0.2

0.3

0.4

0.5

0.6 ZHH→ - + e+e

HH (WW-fusion)νν → - + e+eHH (Combined)νν → - + e+e

) = (-0.8,+0.3)+,e-

M(H) = 125 GeV P(e

Figure 7: Diagrams of the double Higgs production processes, e+e� ⇥ ZHH (left a) and e+e� ⇥⇤⇤HH (left b), and their cross sections as function of

⌅s (right).

SMλ/λ0 0.5 1 1.5 2

SM

σ/σ

0.5

1

1.5

2w/o weight

w/ weight (Optimal)

Zhh @ 500 GeV→-+e+e

= 120 GeVhm

SMλ/λ0 0.5 1 1.5 2

SM

σ/σ

1

2

3

4

w/o weight

w/ weight (Optimal)

hh @ 1 TeVνν→-+e+e

= 120 GeVhm

Figure 8: Cross sections of e+e� ⇥ ZHH (left) and e+e� ⇥ ⇤⇤HH (right) as a function of Higgs self-coupling.

calculable factor corresponding to the search mode. In addition, the recoil mass measurementsprovide absolute cross section measurements of the e+e� ⇥ ZH, process, which can be predictedas Y ⇤

j = Fj · g2HZZ . To combine all of these measurements to exact the 9 couplings, HZZ, HWW ,

Hbb, Hcc, Hgg, H⌅⌅ , Hµµ , Htt, and H⇥⇥ , and the Higgs total width, GH , a method of modelindependent global fit is applied by constructing a �2 which is defined as following:

�2 =i=N

Âi=1

(Yi �Y ⇤

iDYi

)2,

where Yi is the measured value, DYi is the error on Yi, N is the total number of measurements and Y ⇤i

is the predicted value which can always be parameterized by couplings and Higgs total width. Nextstep is to minimize this �2 and get the fitted values of the 10 parameters and their errors. Here weassume all the 9 couplings and the Higgs total width are free parameters without any correlation.The result of our global fit is given in Table 1, at different energies and for both baseline andluminosity upgraded scenarios. The systematic errors and theoretical errors are not consideredhere, which however will be well controlled to below sub-percent level at the ILC.

8. Summary and Acknowlegement

The physics case at the ILC has a solid base complementary to the LHC, and provides a com-

7

Double Higgs-strahlung (DHS) vs VBF

from arXiv:1311.6528

25


Z

H

ZH

He+

e�Z

H

ZH

e+

e�Z

H

ZH

e+

e�Z

H

ZH

e+

e�+ + +


(a)

+ + +


(b)

H

HH

�

��e+

e�

H

H�

��e+

e�

H

H�

��e+

e�

H

H�

e+

e�

��


Cro

ss S

ect

ion / fb

0

0.1

0.2

0.3

0.4

0.5

0.6 ZHH→ - + e+e


) = (-0.8,+0.3)+,e-

M(H) = 125 GeV P(e


⌅s (right).

SMλ/λ0 0.5 1 1.5 2

SM

σ/σ

0.5

1

1.5

2w/o weight

w/ weight (Optimal)


= 120 GeVhm

SMλ/λ0 0.5 1 1.5 2

SM

σ/σ

1

2

3

4

w/o weight

w/ weight (Optimal)


= 120 GeVhm





�2 =i=N

Âi=1

(Yi �Y ⇤

iDYi

)2,





7




e+

e−

e+

e−

Z

h

h

+

++

c2V c3

Double Higgs-strahlung (DHS)dominant below 1 TeV

25


Z

H

ZH

He+

e�Z

H

ZH

e+

e�Z

H

ZH

e+

e�Z

H

ZH

e+

e�+ + +


(a)

+ + +


(b)

H

HH

�

��e+

e�

H

H�

��e+

e�

H

H�

��e+

e�

H

H�

e+

e�

��


Cro

ss S

ect

ion / fb

0

0.1

0.2

0.3

0.4

0.5

0.6 ZHH→ - + e+e


) = (-0.8,+0.3)+,e-

M(H) = 125 GeV P(e


⌅s (right).

SMλ/λ0 0.5 1 1.5 2

SM

σ/σ

0.5

1

1.5

2w/o weight

w/ weight (Optimal)


= 120 GeVhm

SMλ/λ0 0.5 1 1.5 2

SM

σ/σ

1

2

3

4

w/o weight

w/ weight (Optimal)


= 120 GeVhm





�2 =i=N

Âi=1

(Yi �Y ⇤

iDYi

)2,





7




e+

e−

e+

e−

Z

h

h

+

++

c2V c3

Double Higgs-strahlung (DHS)dominant below 1 TeV

c2V c3

Vector Boson Fusion (VBF)dominant above 1 TeV

Expected precision on andc3 c2VCOM energy Precision Process Reference

Expected precision on c3 and c2V

COM Energy Precision Process Reference

ILC

500 GeV[L = 500 fb�1]

�c3 ⇠ 104% DHS ILC TDR, Volume 2, arXiv:1306.6352

1 TeV[L = 1 ab�1]

�c3 ⇠ 28% VBF ILC TDR, Volume 2, arXiv:1306.6352

�c2V ⇠ 20% DHS Contino et al., JHEP 1402 (2014) 006

CLIC

1.4 TeV[L = 1.5 ab�1]

�c3 ⇠ 24%

VBF Rolo↵ (CLICdp Coll.), talk at LCWS14

�c2V ⇠ 7%

3 TeV[L = 2 ab�1]

�c3 ⇠ 12%

�c2V ⇠ 3%

Precision on Higgs trilinear

slightly better than FCC100

(e↵ects at threshold)

Precision on c2V worse

than FCC100

(e↵ects grow with energy)

FCC100 allows for better precision✦ higher energy reach (useful for )✦ higher luminosity at threshold (useful for Higgs trilinear)

�c2V

Gluon Fusion channel Angular dependence

The angular distributionThe signal is also characterised by the angle between the Higgs pair and the

beam axis in the c.o.m. frame

h

h

g gθ

Scattering due to two partial waves andJz = 0d�

d cos ✓

⇠ const. (Jz = 0)

d�

d cos ✓

⇠ sin

2✓ (Jz = ±2)

Jz = ±2



h

h

g gθ

d�

d cos ✓

⇠ const. (Jz = 0)

d�

d cos ✓

⇠ sin

2✓ (Jz = ±2)

✦ in the SM the amplitude comes only from the box diagram and is quite suppressed

Jz = ±2

0 0.2 0.4 0.6 0.8 1

1

cosθ

(dσ/

dcosθ)

/σ

10-1

10

10

-2

-3

10-4

√s = 400GeV

0 0.2 0.4 0.6 0.8 1

1

cosθ

(dσ/

dcosθ)

/σ

10-1

10-2

√s = 700GeV

Jz = ±2

Jz = 0

Scattering due to two partial waves andJz = 0 Jz = ±2



h

h

g gθ

d�

d cos ✓

⇠ const. (Jz = 0)

d�

d cos ✓

⇠ sin

2✓ (Jz = ±2)

✦ in the SM the amplitude comes only from the box diagram and is quite suppressed

Jz = ±2

✦ the BSM diagrams coming from dim. 6 operators only generate contributions with Jz = 0

➡ angular analysis not useful to disentangle NP effects(possible exception dim. 8 operators, extremely hard at LHC)

Scattering due to two partial waves andJz = 0 Jz = ±2

at the LHC and Beyond...b¯b⌧ + ⌧ b¯bWW ⇤ • larger cross section • large bkg • may be...

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