Implications of the Higgs discoveryusers.ictp.it/~smr2463/lect/Djouadi-4.pdfHere, I discuss the...

Implications of the Higgs discovery· · ·

Abdelhak DJOUADI (LPT Paris-Sud)

• First, is it a Higgs?

• Implications for the SM

• Implications for the MSSM: mass

• Other implications for the MSSM

• What next?

ICTP School, 13/06/2013 Implications of the Higgs discovery – A. Djouadi – p.1/26

1. Is it a Higgs?After 48 years of postulat, 30 years of search (and a few heart attacks),“a boson” is discovered at LHC on the 4th of July: Hi(gg)stori cal day!

[GeV]Hm110 115 120 125 130 135 140 145 150

0Lo

cal p

-1110

-1010

-910

-810

-710

-610

-510

-410

-310

-210

-110

1

Obs. Exp.

σ1 ±-1Ldt = 5.8-5.9 fb∫ = 8 TeV: s

-1Ldt = 4.6-4.8 fb∫ = 7 TeV: s

ATLAS 2011 - 2012

σ0σ1σ2

σ3

σ4

σ5

σ6

Higgs boson mass (GeV)110 115 120 125 130 135 140 145

of S

M H

iggs

hyp

othe

sis

SC

L

-710

-610

-510

-410

-310

-210

-110

1

10

99.9%

95%

99%

ObservedExpected (68%)

Expected (95%)

CMS Preliminary-1 = 7 TeV, L = 5.1 fbs-1 = 8 TeV, L = 5.3 fbs


1. First, is it a Higgs?A longstanding and most crucial problem in particle physics :

how to generate particle masses in an SU(2) ×U(1) gauge invariant way?in the Standard Model ⇒ the Higgs–Englert–Brout mechanism

Introduce a doublet of scalar fields Φ=(Φ+

Φ0 ) with 〈0|Φ0|0〉 6= 0:fields/interactions symmetric under SU(2) ×U(1) but vaccum not.

LS=DµΦ†DµΦ−µ2Φ†Φ−λ(Φ†Φ)2

v = (−µ2/λ)1/2 = 246 GeV⇒ three d.o.f. for MW± and MZ.For fermion masses, use same Φ:

LYuk=−fe(e, ν)LΦeR + ...

Residual d.o.f corresponds to spin–0 H particle.

• The scalar Higgs boson: JPC = 0++ quantum numbers (CP–even).• Masses and self–couplings from V : M2

H=2λv2,gH3 = 3M2

H

v, ...

• Higgs couplings ∝ particle masses: gHff = mf

v,gHVV = 2

M2V

v

(since v is known, the only free parameter in the SM is MH or λ).


1. First, is it a Higgs?

Spin: the state decays into γγ• not spin–1: Landau–Yang• could be spin–2 like graviton? Ellis et al.– miracle that couplings fit that of H,– “prima facie” evidence against it:

e.g.: cg 6= cγ, cV ≫ 35cγmany th. analyses (no suspense).

CP: is it CP–even or CP–odd?

HVµVµ vs HǫµνρσZµνZρσ

⇒ dΓ(H→ZZ∗)dM∗

and dΓ(H→ZZ)dφ

ATLAS/CMS: ≈ 3σ for CP-even..

Problem : if H is CP mixture, only0+ component is projected out!(or very large 0 −VV loop cplg).⇒ better probe: µZZ=1.1±0.4!

M* (GeV)

No.

of

Eve

nts

SM

H → Z*Z → (f1f–

1)(f2f–

2)MH = 150 GeV

Spin 1Spin 2

0

5

10

15

20

25

30

30 35 40 45 50 55ϕ

1/Γ

dΓ/d

ϕ

H → ZZ → (f1f–

1)(f2f–

2)MH = 280 GeV

SMpseudoscalar

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0 π/2 π 3π/2 2π

)0+/L0-

ln(L× -2 -30 -20 -10 0 10 20 30

Gen

erat

ed e

xper

imen

ts

0

500

1000

1500

2000

2500

3000

SM, 0+

0-

CMS data

CMS Preliminary -1 = 8 TeV, L = 12.2 fbs -1 = 7 TeV, L = 5.1 fbs


1. First, is it a Higgs?

)µSignal strength ( -1 0 +1

Combined

4l→ (*) ZZ→H

γγ →H

νlν l→ (*) WW→H

ττ →H

bb→W,Z H

-1Ldt = 4.6 - 4.8 fb∫ = 7 TeV: s-1Ldt = 5.8 - 13 fb∫ = 8 TeV: s

-1Ldt = 4.8 fb∫ = 7 TeV: s-1Ldt = 5.8 fb∫ = 8 TeV: s

-1Ldt = 4.8 fb∫ = 7 TeV: s-1Ldt = 5.9 fb∫ = 8 TeV: s

-1Ldt = 13 fb∫ = 8 TeV: s

-1Ldt = 4.6 fb∫ = 7 TeV: s-1Ldt = 13 fb∫ = 8 TeV: s

-1Ldt = 4.7 fb∫ = 7 TeV: s-1Ldt = 13 fb∫ = 8 TeV: s

= 126 GeVHm

0.3± = 1.3 µ

ATLAS Preliminary

SMσ/σBest fit -2 0 2 4

ZZ→H

WW (VH tag)→H

WW (VBF tag)→H

WW (0/1 jet)→H

(VBF tag)γγ →H

(untagged)γγ →H

(VH tag)ττ →H

(VBF tag)ττ →H

(0/1 jet)ττ →H

bb (ttH tag)→H

bb (VH tag)→H

-1 12.2 fb≤ = 8 TeV, L s -1 5.1 fb≤ = 7 TeV, L s

CMS Preliminary = 125.8 GeVH m

Vc0.0 0.5 1.0 1.5

Fc

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

ln L

∆-2

0

2

4

6

8

10

12

14

16

18

20CMS Preliminary

-1 = 7 TeV, L = 5.1 fbs-1 = 8 TeV, L = 5.3 fbs

Vk

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Fk

-2

-1

0

1

2

3

4 SMBest fit

) < 2.3Fk,V

k(L-2 ln ) < 6.0Fk,

Vk(L-2 ln

-1Ldt = 5.8-5.9 fbò

= 8TeV, s

-1Ldt = 4.8 fbò

= 7TeV, sATLAS Preliminary

From ATLAS/CMS results:

Higgs couplings to elementary particles as predicted by Hig gs mechanism:• couplings to WW,ZZ, γγ roughly as expected for a CP-even Higgs• couplings proportionial to masses as expected for the Higgs bosonSo, it is not only a “new particle”, the “126 GeV boson”, a “new state”...

IT IS A HIGGS BOSON!

But is it THE SM Higgs boson or A Higgs boson from some extension?ICTP School, 13/06/2013 Implications of the Higgs discovery – A. Djouadi – p.5/26

1. First, is it a Higgs?a SM or a BSM Higgs?

To check this you need very precise measurements to see small deviations...


2. Implications in the SMSo its looks like expected in SM ⇒a triumph for high-energy physics!Indirect constraints from EW data a

H contributes to RC to W/Z masses:

HW/Z W/Z

∝ απlog MH

MW+· · ·

Fit the EW precision measurements,one obtains MH = 92+34

−26 GeV, or

MH<∼ 160 GeV at 95% CL

compared with the measured mass

MH≈126 GeV.A very non–trivial consistency check!(remember the stop of the top quark!).The SM is a very successfull theory!

a Still some problems with AbFB (LEP), At

FB (TeV) and g−2 but not severe...

0

1

2

3

4

5

6

10030 300

mH [GeV]

∆c

2

Excluded

∆ahad =∆a

(5)

0.02750±0.000330.02749±0.00010incl. low Q2 data

Theory uncertaintyJuly 2011 mLimit = 161 GeV

(GeV)Xm120 122 124 126 128 130

SMs/

s

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

ln L

∆-2

024

68101214161820

CMS Preliminary -1 12.2 fb£ = 8 TeV, L s -1 5.1 fb£ = 7 TeV, L s

ZZ® + H gg ®H


2. Implications in the SM• The theory preserves unitarity:

without H: |A0(VV→VV)|∝E2

including H: |A0|∝M2H/v

2

theory unitary if MH<∼700 GeV...

V

V

V

V H

• Particle spectrum complete:Fourth generation excluded byH → ZZ,WW, γγ,bb rates...

• Extrapolable up to highest scales.λ(Q2)λ(v2)

≈1+ 32M4

W+M4

Z−4m4

t

16π2v4 logQ2

v2

tops make λ<0: unstable vacuum

ΛC∼MPl ⇒ MH>∼129GeV!

at 2loops for mpolet =173 GeV.....

Degrassi et al., Bezrukov et al.but what is measured mt value?• SM = TOE? Maybe not (?):

mν , DM, GUT, hierarchy...

mb′ =mt′+50 GeV=600 GeV

γγ@LHC

MH=125 GeV

Vbb@Tevatron

σ(H)×BR|SM4/SM

mν′ = mℓ′ [GeV]100 200 300 400 500 600

1

0.1

H+ +

f/V

Tev⊕lHCLHCILCstable

stablemeta-

unstable

EW vacuum:

95%CL

MH [GeV]

mpole

t[G

eV

]

132130128126124122120

182

180

178

176

174

172

170

168

166

164


2. Implications in the SM

Rates compatible withthose expected in the SM

Fit of all LHC Higgs data ⇒,

agreement at 20–30% levelwith SM predictions!

Moreau+ADand >20 TH+EXP analyses

�

99�

99�

95�

68�

SM

Fit of Μ ratios

�March 2013�

0.0 0.2 0.4 0.6 0.8 1.0 1.2

�1.0

�0.5

0.0

0.5

1.0

1.5

cV

c f

Some beyond the SM scenarios are in ‘mortuary”:• Higgsless models, extreme Technicolor and composite scena rios, ..• fermiophobic Higgs, gauge-phobic Higgs, 4th generation, . ..Some beyond the SM scenarios are in “hospital”:Other BSM scenarios are strongly constrained...

Here, I discuss the example of Supersymmetry and the MSSM:ICTP School, 13/06/2013 Implications of the Higgs discovery – A. Djouadi – p.9/26

3. Implications for the MSSM: mass

In the MSSM: two Higgs doublets: H1 =(

H01

H−

1

)

and H2 =(

H+

2

H02

)

,

After EWSB (which can be made radiative: more elegant than in SM):

Three dof to make W±L ,ZL ⇒ 5 physical states left out: h,H,A,H±

Only two free parameters at tree–level: tanβ,MA but rad. cor. important:

Mh<∼MZ|cos2β|+RC<∼130 GeV , MH≈MA≈MH±<∼MEWSB

– Couplings of h,H to VV are suppressed; no AVV couplings (CP).– For tanβ ≫ 1: couplings to b (t) quarks enhanced (suppressed).

Φ gΦuu gΦdd gΦV V

h cosαsinβ→ 1 sinα

cos β→ 1 sin(β − α)→ 1H sinα

sinβ→ 1/ tan β cosαcos β → tan β cos(β − α)→ 0

A 1/ tan β tanβ 0In the decoupling limit: MSSM reduces to SM but with a light SM Higgs .

this decoupling limit occurs in many extensions....At tan β≫1, one SM–like and two CP–odd like Higgses with cplg to b, τMA≤Mmax

h ⇒h≡A,H≡HSM , MA≥Mmaxh ⇒H≡A,h ≡HSM


3. Implications for the MSSM: massThe mass value 126 GeV is rather large for the MSSM h boson,

⇒ one needs from the very beginning to almost maximize it...Maximizing Mh is maximizing the radiative corrections; at 1-loop:

MhMA≫MZ→ MZ|cos2β|+ 3m4

t

2π2v2sin2 β

[

logM2

S

m2t

+X2

t

M2S

(

1− X2t

12M2S

)]

• decoupling regime with MA∼O(TeV);• large values of tan β >∼ 10 to maximize tree-level value;• maximal mixing scenario: Xt =

√6MS;

• heavy stops, i.e. large MS=√mt1

mt2;

we choose at maximum MS<∼3 TeV, not to have too much fine-tuning....

• Do the complete job: two-loop corrections and full SUSY spec trum• Use RGE codes (Suspect) with RC in DR/compare with FeynHiggs (OS).Perform a full scan of the phenomenological MSSM with 22 free parameters• determine the regions of parameter space where 123≤Mh ≤129GeV(3 GeV uncertainty includes both “experimental” and “theor etical” error)• require h to be SM–like: σ(h)×BR(h)≈ HSM (H = HSM) later)Many anlayses! Here, the one from Arbey et al. 1112.3028+120 7.1348



Main results:• Large MS values needed:– MS ≈ 1 TeV: only maximal mixing– MS ≈ 3 TeV: only typical mixing.• Large tan β values favoredbut tan β≈3 possible if MS≈3TeV

How light sparticles can be withthe constraint Mh = 126 GeV?• 1s/2s gen. q should be heavy...But not main player here: the stops:⇒ mt1

<∼ 500 GeV still possible!•M1,M2 and µ unconstrained,• non-univ. mf : decouple ℓ from qEW sparticles can be still very lightbut watch out the new limits..



Constrained MSSMs are interesting from model building poin t of view:

– concrete schemes: SSB occurs in hidden sectorgravity,..→ MSSM fields

– provide solutions to some MSSM problems: CP, flavor, etc..– parameters obey boundary conditions ⇒ small number of inputs...• mSUGRA: tan β , m1/2 , m0 , A0 , sign(µ)• GMSB: tanβ , sign(µ) , Mmes , ΛSSB , Nmess fields

• AMSB: , m0 , m3/2 , tan β , sign(µ)full scans of the model parameters with 123 GeV≤Mh≤129 GeV

very strong constraints and some (minimal) models ruled out ...ICTP School, 13/06/2013 Implications of the Higgs discovery – A. Djouadi – p.13/26


As the scale MS seems to be large, consider two extreme possibilities

• Split SUSY: allow fine–tuningscalars (including H2) at high scalegauginos–higgsinos at weak scale(unification+DM solutions still OK)Mh ∝ log(MS/mt) → large• SUSY broken at the GUT scale...give up fine-tuning and everything elsestill, λ∝M2

H related to gauge cplgs

λ(m)=g21(m)+g2

2(m)

8(1+ δm)

... leading to MH=120–140 GeV ...In both cases small tanβ needed...note 1: tanβ ≈ 1 possiblenote 2: MS large and not MA possible!?Consider general MSSM with tanβ ≈ 1!

11�

12�

125

13�

14�

15�

16�

1�4

1�6

1�8

1�1�

1�12

1�14

1�16

Mh

��eV

)

M� ��eV)

�plit �U�Y

tan � � 1

tan � � 2

tan � � 5

tan � � 5�

11�

12�

125

13�

14�

15�

16�

1�4

1�6

1�8

1�1�

1�12

1�14

1�16

Mh

��eV

)

M� ��eV)

Highscale SUSY

tan � � 1

tan � � 2

tan � � 5

tan � � 5�


4. Other implications for the MSSM

There are other (stringent) constraints on pMSSM to be inclu ded:• production/decay rates of the observed Higgs particle;• CMS and ATLAS pp → A/H/(h)→ττ and t → bH+ searches;• non observation of heavier Higgses in the ZZ,WW,tt channels ;• constraints from sparticle searches and eventually Dark Ma tter,• constraints from flavor: at least (direct!) limits from Bs→µµ...

)mSignal strength ( -1 0 +1

Combined

4l® (*) ZZ®H

gg ®H

nln l® (*) WW®H

tt ®H

bb®W,Z H

-1Ldt = 4.6 - 4.8 fbò = 7 TeV: s-1Ldt = 5.8 - 13 fbò = 8 TeV: s

-1Ldt = 4.8 fbò = 7 TeV: s-1Ldt = 5.8 fbò = 8 TeV: s

-1Ldt = 4.8 fbò = 7 TeV: s-1Ldt = 5.9 fbò = 8 TeV: s

-1Ldt = 13 fbò = 8 TeV: s

-1Ldt = 4.6 fbò = 7 TeV: s-1Ldt = 13 fbò = 8 TeV: s

-1Ldt = 4.7 fbò = 7 TeV: s-1Ldt = 13 fbò = 8 TeV: s

= 126 GeVHm

0.3± = 1.3 m

ATLAS Preliminary

(GeV)Hm

SM

σ/σ

95%

CL lim

it o

n

-110

1

10

Observed

Expected (68%)

Expected (95%)

Observed

Expected (68%)

Expected (95%)

CMS Preliminary -1 = 8 TeV, L = 12.2 fbs

-1 = 7 TeV, L = 5.1 fbs

100 200 300 400 600 1000

Observed

Expected (68%)

Expected (95%)

CMS Preliminary -1 = 8 TeV, L = 12.2 fbs

-1 = 7 TeV, L = 5.1 fbs

[GeV]Am200 400 600 800

!ta

n

0

5

10

15

20

25

30

35

40

45

50CMS -1 = 7+8 TeV, L = 17 fbsPreliminary,

= 1 TeVSUSY

scenariomax

hMSSM m

Observed

Expected

expected" 1#

expected" 2#

LEP

95% CL Excluded Regions

M



Higgs searches are more complicated/challenging in the MSS M case

q

�q

V

�

�

H

V

Higgs{strahlung

�

qq

V �

V

�

H

qq

Ve tor boson fusion

�

gg

H

Q

gluon{gluon fusion

�

gg

H

Q

�

Q

in asso iated with Q

�

Q

t

�

t�

Z�

W�

qq�

b

�

b�

gg!�

pp! H

+

�

tb

A

Hh

tan� = 30

p

s = 14 TeV

�(pp! �+X) [pb℄

M

�

[GeV℄

1000100

1000

100

101

0.1

0.01

• More Higgs particles: Φ=h,H,A,H±:– some couple almost like the SM Higgs,– but some are more weakly coupled.• In general same production as in SMbut also new/more complicated processses(rates can be smaller or larger than in SM).• Possibility of different decay modes(and clean decays eg into γγ suppressed)• Impact of light SUSY particles?⇒ In general very complicated situation!But simpler in the decoupling regime:– h as in SM with Mh=115−130GeV– dominant mode: gg,bb→H/A→ττIt is even more tricky in beyond MSSM!and also in some non–SUSY extensions...



There are other (stringent) constraints on pMSSM to be inclu ded:• production/decay rates of the observed Higgs particle;• CMS and ATLAS pp → A/H/(h)→ττ and t → bH+ searches;• non observation of heavier Higgses in the ZZ,WW,tt channels ;• constraints from sparticle searches and eventually Dark Ma tter,• constraints from flavor: at least (direct!) limits from Bs→µµ...


4. Other implications for the MSSMWhat about the low tan β regime?

• tanβ<∼3 usually “excluded” by LEP2:Mh

>∼114 GeV for BMS with MS≈1 TeV.

Be we can be more relaxed: MS ≫ MZ

⇒ tanβ as low as 1 could be allowed!

• We turn Mh≈MZ| cos 2β|+RC toRC= 126 GeV - f(MA, tan β)

ie. we ”trade” RC with the measured Mh

MSSM with only 2 inputs at HO: MA, tan β⇒ model indep. effective approach!

• Constraints on the low tan β region:– H→WW,ZZ in SM– H→tt in BSM scenarios– H→hh and A →hZ..Use current data for constraints...

Quevillon+AD


4. Other implications from the MSSM

Sets stingent constraints on pMSSM regimes/benchmark scen arios?• Heavier CP–even H being the observed Higgs is now excluded..• Close h,H,A,H± (intense coupling regime) excluded..• Small αeff scenario with ghbb ≈ 0 and thus small Γh:ruled out by LHC/Tevatron data: ex: loose Wh →ℓνbb signal..• gluophobic h with ghgg ≪ gHSMgg due to squark loops?ruled out by ZZ,WW, γγ signals at LHC (and also the h mass)

But some difference with the SM!a >∼ 2σ excess in H → γγ.• Statistical fluctuation?• Systematics problem?• Maybe QCD uncertainties?

or a combination of the three..Hope it is due to SUSY!– total Higgs width suppressed?– SUSY effects in h γγ loop?

∆thLHCHWG

∆thµ+PDF+EFT

ATLAS ⊕ CMS

ATLAS

CMS

MH = 126 GeV √s = 7⊕ 8 TeV

RH→γγ

σobs/σSM

2.521.510.50



A 126 GeV Higgs provides information on BSM and SUSY in partic ular:•MH=119 GeV would have been a boring value: everybody OK..•MH=145 GeV would be a devastating value: mass extinction..•MH≈126 GeV is Darwinian: (natural) selection among models..SUSY spectrum heavy; except maybe for weakly interactingsparticles and also stops ⇒ more focus on them in SUSY searches!

One has to include other Higgs/SUSY searches in particular:•H/A/H± searches at the LHC are becoming very constraining..• SUSY searches and flavor constraints are to be taken into acco unt.• No more room for some search channels such as H/A → µµ,bb,..(need to start thinking bout changing the benchmark scenari os....)• Some search channels at low tan β still relevant: H →WW,ZZ,tt,hh,..(need to continue/adapt the SM Higgs searches at high masses !)

7–8 TeV LHC for the lightest h and 13–14 TeV LHC for H/A/H +?and maybe some supersymmetric particles will show up?


5. What next?Even if no sign of BSM physics is seen: is Particle Physics “cl osed”?

No! Need to check that H is indeed responsible of sEWSB (and SM -like?)Measure its fundamental properties in the most precise way:

• its mass and total decay width (invisible width due to dark ma tter?),• its spin–parity quantum numbers and check SM prediction for them,• its couplings to fermions and gauge bosons and check that the y areindeed proportional to the particle masses (fundamental pr ediction!),• its self–couplings to reconstruct the potential VH that makes EWSB.Possible for MH≈ 126 GeV as all production/decay channels useful!

ttH

ZH

WH

Hqq

gg→H√

s = 14 TeV

σ(pp → H + X) [pb]

MH [GeV]500400300230180145120100

100

10

1

0.1Zγ

γγ

tt

ZZ

WW

gg

µµ

ss

cc

ττ

bb

BR(H)

MH [GeV]500400300250200145120100

1

0.1

0.01

0.001

0.0001


5. What next?

• Look at various H production/decaychannels and measure Nev = σ ×BR• But large errors mainly due to:– experimental: stats, system., lumi...– theory: PDFs, HO/scale, jetology...total error about 20–30% in gg → HHjj contaminates VBF (now 30%)..⇒ ratios of σxBR: many errors out!Deal with width ratios ΓX/ΓY

– TH on σ and some EX errors– parametric errors in BRs– TH ambiguities from Γtot

H

• Achievable accuracy:– now: 20–30% on γγ/VV, ττ/VV– future: few % at HL–LHC!

Moreau+ADSufficient to probe BSM physics?

Baglio+AD

500250115

1.301.151.000.850.70

∆total (NNLO+EW)

MSTW

√s = 7 TeV

σ(gg → H) [pb]

MH [GeV]

500450400350300250200150

20

10

5

1

�

99�

99�

95�

68�

SM

Fit of Μ ratios

�March 2013�

0.0 0.2 0.4 0.6 0.8 1.0 1.2

�1.0

�0.5

0.0

0.5

1.0

1.5

cV

c f

�

�

LHC , 14TeV

3000 fb�1

99�

95�

68�

0.80 0.85 0.90 0.95 1.00 1.05

0.65

0.70

0.75

0.80

0.85

0.90

cV

c f


5. What next?Challenge: measurement of Higgs self-couplings and access to VH.

• gH3 from pp → HH+X ⇒• gH4 from pp →3H+X, hopeless.Various processes for HH prod:only gg → HHX relevant...

qq → ZHH

qq′ → WHH

qq′ → HHqq′

gg → HH

√s = 14 TeV, MH = 125 GeV

σ(pp → HH +X)/σSM

λHHH/λSMHHH

5310-1-3-5

40

35

30

25

20

15

10

5

0

Baglio et al., arXiv:1212.5581

� �

HH

H

gg

Q

�

�

�qq

V

�

V

HH

� �

qq

qq

V

�

V

�

HH

1

LO QCD

NNLO QCD

NLO QCD

NLO QCD

qq/gg → ttHH

qq → ZHHqq′ → WHH

qq′ → HHqq′

gg → HHMH = 125 GeV

σ(pp → HH+X) [fb]

√s [TeV]

1007550258

1000

100

10

1

0.1

•H → bb decay alone not clean•H → γγ decay very rare,•H → ττ would be possible?•H → WW not useful?– bbττ,bbγγ viable?– but needs very large luminosity.

Maybe even needs an ILC.....ICTP School, 13/06/2013 Implications of the Higgs discovery – A. Djouadi – p.23/26

5. What next?

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 GeVσ(e+e− → HX) [fb]

√s [GeV]

200 350 500 700 1000 2000 3000

1000

100

10

1

0.1

0.01

Very precise measurementsmostly at

√s<∼ 500 GeV

and mainly in e+e− → ZH(with σ ∝ 1/s) and ZHH, ttH

gHWW ±0.012gHZZ ±0.012gHbb ±0.022gHcc ±0.037gHττ ±0.033gHtt ±0.030λHHH ±0.22MH ±0.0004ΓH ±0.061CP ±0.038

⇒ difficult to be beaten by anything else for ≈ 125 GeV Higgs⇒ welcome to the ILC!


5. What next?

Now, this is not the end.

It is not even the beginning to the end.

But it is, perhaps, the end of the beginning.

Sir Winston Churchill, November 1942

We hope that at the end we finallyunderstand the EWSB mechanism,but there is a long way untill then....and there might be many surprises!


Implications of the Higgs discoveryusers.ictp.it/~smr2463/lect/Djouadi-4.pdfHere, I discuss the...

Documents

Transcript of Implications of the Higgs discoveryusers.ictp.it/~smr2463/lect/Djouadi-4.pdfHere, I discuss the...