Higgs portal Dark Matter at LHC and other colliders...Higgs portal Dark Matter at LHC and other...

Higgs portal Dark Matter

at LHC and other colliders

Abdelhak DJOUADI

(CNRS & LAPTh)

1. The Higgs portal to Dark Matter2. Invisible Higgs at the LHC

3. Higgs properties at e+e− colliders4. Comparison with astroparticle physics

5. Heavy DM states6. Conclusion

Valencia 14/12/2018 Higgs portal DM – A. Djouadi – p.1/18

1. The Higgs portal to Dark Matter

1) Rotation curve of (clusters of) galaxiesDM indeed exists:

2) CMB and large scale structure formation

It is a new/unknown particle: no SM state (eg ν) can do the job.

A crucial hint for physics beyond the SM of strong+EW forces!

25% of energy budget of UniverseMakes

80% of total matter of Universe

PLANCK: ΩDMh2 = 0.1188± 0.0010

• Neutral particle and hence dark (a charged particle will shine...).

• Cold or not too warn and hence non-relativistic (ν do not work...).

• Very weakly interacting (reason why we did not observe it yet).

• Stable or at least very long lived particle: τDM ≫ 1017 s.

• Possibly a relic from the early Universe: a window to the origin.

In short, a WIMP. It worths the effort searching for it!



WIMPS appear in models for naturalness/hierarchy problems:

– LSP: lightest neutralino of SUSY with Rp conserved

Examples: – LKP: lightest Kaluza-Klein state in extra-dimensions.

– LTP: lightest T-odd in Little Higgs/composite

We choose a different way: simply Agnosticism and Occam razor:

postulate the existence of a weakly interacting massive particle:

• a singlet particle but spin 0, 12

, 1 i.e. a scalar, vector or fermion

• QED neutral + isosinglet, no SU(2)xU(1) charge: no Z couplings

• Z2 parity for stability: no couplings or mixing with fermions

Hence, only couplings with the Higgs bosons: Higgs portal DM,

– annihilates into SM particles through s-channel Higgs exchange;

– can be produced in pairs via Higgs boson exchange or decays.

Again Occam razor: assume only the SM-like Higgs boson.



Lagrangians:

∆LS = −12M2

SS2 − 1

4λSS

4 − 14λHSSΦ

†ΦS2

∆LV = 12M2

VVµVµ+ 1

4λV(VµV

µ)2+ 14λHVVΦ

†ΦVµVµ

∆Lχ = −12Mχχχ− 1

4

λHχχ

ΛΦ†Φχχ

EWSB: Φ → 1√2(v+H) with v=246 GeV and m2

S=M2S+

14λHSSv

2 ...

Two free parameters: DM mass mX and DM-Higgs coupling λHSS

Of course effective and even non-renormalisable models. EFT for:

• Scalars: inert Higgs doublet models (comes with others states).

• Vectors: may be related to a spontaneously broken U(1) symmetry.

• Fermions: fourth family, singlet-doublet or vector-like leptons?

All these are renormalisable, unitary, perturbative (up to cut-off) ...

But where are all the new (companion) states gone? Should have been seen?

– Z2 symmetry: all new particles decay at end into the DM state;

– eventually some mass degeneracy with the invisible DM particle.

⇒ missing energy and soft SM particle signature: very difficult!



Direct Detection:

•SM

DM

SM

DM

scattering on nucl. target:XENON ⇒ LZ,DARWIN

Indirect Detection:

•DM

DM

SM

SM

annihilation products: γ, νHESS,;..⇒ CTA,HAWK,

Detection at colliders:

•SM

SM

DM

DM

missing energy signatureLHC ⇒ HL-LHC,e+e−,pp


2. Invisible Higgs at the LHC

For light DM states, only possible handle at colliders is Higgs decays:

Γinv(H → SS) =λ2HSS

v2βS

64πMH

Γinv(H → VV) =λ2HVV

v2M3HβV

256πM4V

(

1− 4M2

V

M2H

+ 12M4

V

M4H

)

Γinv(H → ff) =λ2Hff

v2MHβ3f

32πΛ2

Possible only for mX < 12MH ≈ 60 GeV; depends on mX, λHXX:

One has to check also the relic density/Planck: only one input...



A) Direct: measurement of total Higgs decay width via interference

ΓSMH =4.07MeV ⇒ too small to be resolved experimentally.

If MH>∼ 200GeV, ΓH>1GeV ⇒ possible in H → ZZ → 4ℓ

But in pp→H→ZZ→4f , about 20% are for MVV>∼ 2MV

Indirect measurement of ΓH via interference with pp→ZZ continuum

SMHΓ/HΓ

0 1 2 3 4 5

)λ2

ln(

0

2

4

6

8

10

12

14ExpectedStat. only

Expected

ObservedStat. only

Observed

ATLAS

ν 4l,2l2→ ZZ →H* 113 TeV, 36.1 fb

g/V, offshellκ = g/V, onshellκ

σ1

σ2

(MeV)HΓ0 20 40 60

ln L

∆-2

0

2

4

6

8

10

12

14 WW (observed)→H WW (expected)→H

ZZ (observed)→H ZZ (expected)→H

ZZ+WW (observed)→H ZZ+WW (expected)→H

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

68% CL

95% CL

But the constraints are too loose: ΓH/ΓSMH

<∼ 3−4 only.



B) Indirectly: measurements of the Higgs decay branching ratios

κ2X = σ(X)/σ(X)|SM = Γ(XX)/Γ(XX)|SM = g2HXX/g

2HXX|SM

Γ(VV)→κ2V, Γ(ff)→κ2f , σ(VH)→κ2V, σ(VBF)→0.74κ2W+0.26κ2ZΓ(γγ)→κ2γ=1.5κ2W+0.1κ2t−0.7κtκW, σ(ggH)→κ2g=1.06κ2t−0.07κtκb

Parameter value2− 1− 0 1 2 3

|µκ|

bκ

|τκ|

tκ

Wκ

Zκ

Run 1LHC

CMS and ATLAS ATLAS+CMS

ATLAS

CMS

intervalσ1

intervalσ2

fVκ

0 0.5 1 1.5 2

f Fκ

2−

1−

0

1

2

Combined γγ→H

ZZ→H WW→H

ττ→H bb→H

68% CL

95% CL

Best fit

SM expected

Run 1 LHC

CMS and ATLAS

κ2H=0.57κ2b+0.22κ2W+0.06κ2τ+0.03κ2Z+0.03κ2c+0.0023(κ2γ+ κ2Zγ)

Global ATLAS+CMS fit gives BR(H→ invisible) <∼ 20%@95%CL



C) Even more direct: search for Higgs decaying invisibly.

q

q

V

H

q

qH

g

g

t

H

qq→WH → ℓν+ET/ qq→qqH → jj+ET/ gg →Hg → j+ET/qq→ZH → ℓℓ+ET/ high-mass,pT, η jets also 2j, high rate.

Choudhury+Roy, ..., Eboli+Zeppenfeld AD,Falkowski,Mambrini...

inv)→B(H

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

1-E

xclu

sio

n C

L

-210

-110

1

Observed

Expected Median

σ 1 ±Expected

σ 2 ±Expected

95% CL

-1 = 13TeV, 36.1 fbsµµee+

ATLAS

[GeV]Hm100 150 200 250 300 350 400

(SM

)V

BF

σ inv)/

→ x

B(H

σ

0.5

1

1.5

2

2.5 invisible→CMS VBF H

-1 = 8 TeV, L = 19.5 fbs

95% CL limits

Observed limit

Expected limit

)σExpected limit (1

)σExpected limit (2

Combined VBF-tag Z(ll)H-tag V(qq')H-tag ggH-tag

SM

95%

CL u

pper

limit o

n σ

x B

(H →

inv)/

σ

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Observed

Median expected

68% expected

95% expected

(13 TeV)-1

35.9 fb

CMS

Here also ATLAS+CMS combo gives BR(H→invisible) <∼20%@95%CL



D) A combination of all these channels/possibilities

− −

Λ

s

ss

❱s ❱ s

s

❱s s

All in all at Run II LHC: BR(H → inv) < 20%.

This not very constraining after all. can this be improved? Of course!


3. Invisible Higgs in the future

High–Luminosity LHC:√s = 14 TeV and L = 3ab−1

Improve the sensitivity by factor of 2: BR(H→invisible) <∼10%



Higher energy pp colliders ⇒ √s = 100 TeV and L = a few ab−1

bb → H

qq/gg → ttH

qq → ZHqq′ → WH

qq′ → Hqq′gg → H

MH = 125 GeV

pp → H + X

√s [TeV]

σ(√

s)/

σ(√

s=

13TeV)

10075502513

100

10

1

Improve the sensitivity by another factor of 2: BR(H→invisible) <∼5%



Best deal ever a future e+e− machine:√s = 240 GeV and L = 1ab−1

e−

e+

Z∗

•

H

Z

•

e−

e+

V∗

V∗

H

νe/e−

νe/e+

•

e+

e−

H

t

t

•

e+

e−

H

H

Z

HHνν

HHZ

Htt

HZ

He+e−

Hνν

MH=125 GeV

σ(e+e− → HX) [fb]

√s [GeV]

200 350 500 700 1000 2000 3000

1000

100

10

1

0.1

0.01

Very precise measurements

mostly at√s≈250 GeV

and mainly in e+e− → ZH

gHWW ±0.01gHZZ ±0.01gHbb ±0.01gHcc ±0.03gHττ ±0.03gHtt ±0.05λHHH ±0.2MH ±0.0004ΓH ±0.05CP ±0.03

Improve the sensitivity very seriously: BR(H→invisible) <∼1%In fact: a BR(H→ inv) of 1% can be observed at the 5σ level

and a BR(H→ inv) of 5% can be measured with a 10% accuracy...Valencia 14/12/2018 Higgs portal DM – A. Djouadi – p.13/18

4. Comparison with astroparticle experiments

• Relic density ∝ 1/〈σ(XX → H → f f)vr〉 annihilation rate.

〈σXfermvr〉 = λ2

HXXm2

ferm

16π1

(4m2X−M2

H)2δX, δS = 1, δV = 1

3, δf =

12

v2r

Λ2

In principle needs to fit the Planck value: ΩDMh2=0.119±0.0010

• Spin–independent direct detection, simple for S, V, f DM states:

σSIX−N =

λ2HXX

16πM4H

m4Nf2N

(mX+mN)2δ′X, δS = δV = 1, δf =

4Λ2

BRinvX ≡ BR(H → inv) = Γ(H→XX)

ΓSMH

+Γ(H→XX)=

σSIXp

ΓtotH

/rX+σSIXp

Direct detection:

BRinvX ≃ (σSI

Xp/10−9pb)[δX + (σSI

Xp/10−9pb)]−1

δS = 400 (10 GeV/mS)2 , δV = 4× 10−2 (mV/10 GeV)2 , δf = 3.5

Indirect detection:

BRinvX ≃ (〈σvr〉/10−10GeV−1)[δX + (〈σvr〉/10−10GeV−1)]−1

δS = 2.4× 10−2δV = 1.3× 10−6 (mV/10GeV)4 δf = 3.9× 10−11 (mf/10


4. Comparison with astroparticle experiments

Arcadi,AD


5. Heavy DM states

Heavy DM states to be produced in pairs in continuum at pp colliders:

q

q

V

H

q

qH

g

g

t

H

• Exactly same channels as before but with and off-shell Higgs boson.

• Suppressed by the Higgs virtuality and small couplings to DM.

• Needs high energies, very high luminosities and some real efforts....

• Superseded by direct detection limits in all envisageable cases..

pp → FF + j

pp → SS + j

pp → VV + j

λhχχ = 1

√s = 14 TeV

.

mχ [GeV]

σ[fb]

550500450400350300250200150100

102

101

100

10−1

10−2

10−3

pp → FF + jj

pp → SS + jj

pp → VV + jj

λhχχ = 1

√s = 14 TeV

.

mχ [GeV]

σ[fb]

450400350300250200150100

101

100

10−1

10−2

10−3

pp → FF + Z

pp → FF + W±

pp → SS + Z

pp → SS + W±

pp → VV + Z

pp → VV + W±

λhχχ = 1

√s = 14 TeV

.

mχ [GeV]

σ[fb]

600500400300200100

100

10−1

10−2

10−3

10−4

10−5

AD,Quevillon


5. Heavy DM states

Heavy DM states to be produced in pairs in continuum at pp colliders:

q

q

V

H

q

qH

g

g

t

H

• Exactly same channels as before but with and off-shell Higgs boson.

• Suppressed by the Higgs virtuality and small couplings to DM.

• Needs high energies, very high luminosities and some real efforts....

• Superseded by direct detection limits in all envisageable cases..

pp → FF + j

pp → SS + j

pp → VV + j

λhχχ = 1

√s = 100 TeV

.

mχ [GeV]

σ[fb]

1000900800700600500400300200100

104

103

102

101

100

10−1

10−2

10−3

pp → FF + jj

pp → SS + jj

pp → VV + jj

λhχχ = 1

√s = 100 TeV

.

mχ [GeV]

σ[fb]

1000900800700600500400300200100

103

102

101

100

10−1

10−2

10−3

pp → FF + Z

pp → FF + W±

pp → SS + Z

pp → SS + W±

pp → VV + Z

pp → VV + W±

λhχχ = 1

√s = 100 TeV

.

mχ [GeV]

σ[fb]

1000900800700600500400300200100

101

100

10−1

10−2

10−3

10−4

10−5


6. Conclusions

• Dark matter exists, maybe only reachable sign of new physics?

• The Higgs portal to DM is one of the most minimal realizations.

• Even more minimal if only the SM–like Higgs state is considered.

• But scenario tested at LHC in Higgs searches/measurements:

– measurements of total Higgs width and various visible BRs;

– direct searches for missing energy signatures.

– possibility of going off-shell not that promising.

• Limits from LHC superseded by future astrophysics sensitivity.

• But I didn’t tell you the really interesting part of the story yet:

– concrete realizations of Higgs-DM and search for DM companions;

– extending the Higgs sector makes it even more interesting.

Needs further investigations at the LHC and also future ee and pp

colliders besides all experiments in astroparticle physics .


Higgs portal Dark Matter at LHC and other colliders...Higgs portal Dark Matter at LHC and other...

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