the big deal with the little higgs - desyreuter/downloads/biglittle.pdf · j. reuter the big deal...
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![Page 1: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/1.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
The Big Deal with the Little Higgs
Jürgen Reuter
DESY, Hamburg
Edinburgh, 08.Dec.2005
![Page 2: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/2.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
The Higgs boson: pros and cons
Electroweak interactions mediated by massive gauge bosons:(SU(2)× U(1) gauge theory)
Problem: Mass terms for W,Z and fermions not gauge invariant
I Formal Solution: Introduction of a field which makes Lagrangiangauge-invariant: ⇒ Higgs field
I Spontaneous symmetry breaking: Higgs gets a Vacuum Expectationvalue v ∼ 250 GeV
I Data prefers a weakly interacting theory at the TeV scale⇒ Higgsfield corresponds to light Higgs particle (mh < 300 GeV)
I Fine-tuning/Hierarchy problem: quantum corrections δm2h ∝ Λ2
Λ new physics scale
I Solution: Symmetry cancels quantum corrections, broken at lowerscale F ∼ 1 TeV
![Page 3: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/3.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
The Higgs boson: pros and cons
Electroweak interactions mediated by massive gauge bosons:(SU(2)× U(1) gauge theory)
Problem: Mass terms for W,Z and fermions not gauge invariant
I Formal Solution: Introduction of a field which makes Lagrangiangauge-invariant: ⇒ Higgs field
I Spontaneous symmetry breaking: Higgs gets a Vacuum Expectationvalue v ∼ 250 GeV
I Data prefers a weakly interacting theory at the TeV scale⇒ Higgsfield corresponds to light Higgs particle (mh < 300 GeV)
I Fine-tuning/Hierarchy problem: quantum corrections δm2h ∝ Λ2
Λ new physics scale
I Solution: Symmetry cancels quantum corrections, broken at lowerscale F ∼ 1 TeV
![Page 4: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/4.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
The Higgs boson: pros and cons
Electroweak interactions mediated by massive gauge bosons:(SU(2)× U(1) gauge theory)
Problem: Mass terms for W,Z and fermions not gauge invariant
I Formal Solution: Introduction of a field which makes Lagrangiangauge-invariant: ⇒ Higgs field
I Spontaneous symmetry breaking: Higgs gets a Vacuum Expectationvalue v ∼ 250 GeV
I Data prefers a weakly interacting theory at the TeV scale⇒ Higgsfield corresponds to light Higgs particle (mh < 300 GeV)
I Fine-tuning/Hierarchy problem: quantum corrections δm2h ∝ Λ2
Λ new physics scale
I Solution: Symmetry cancels quantum corrections, broken at lowerscale F ∼ 1 TeV
![Page 5: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/5.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Higgs as Pseudo-Goldstone Boson
Traditional (SUSY):Spin-Statistics =⇒ Contribu-tions from bosons and fermionscancel
Little Higgs:Global Symmetries: =⇒Quantum corrections of parti-cles of like statistics cancel
Why is the Higgs light in Little Higgs models?
Nambu-Goldstone Theorem: Spontaneous breaking of a global sym-metry leads to massless (Goldstone) boson(s) in the spectrum
Old Idea: Georgi/Pais, 1974; Georgi/Dimopoulos/Kaplan, 1984
Light Higgs as Pseudo-Goldstone boson ⇔ spontaneously bro-ken (approximate) global symmetry
� w/o Fine-Tuning: v ∼ Λ/4π
![Page 6: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/6.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Higgs as Pseudo-Goldstone Boson
Traditional (SUSY):Spin-Statistics =⇒ Contribu-tions from bosons and fermionscancel
Little Higgs:Global Symmetries: =⇒Quantum corrections of parti-cles of like statistics cancel
Why is the Higgs light in Little Higgs models?
Nambu-Goldstone Theorem: Spontaneous breaking of a global sym-metry leads to massless (Goldstone) boson(s) in the spectrum
Old Idea: Georgi/Pais, 1974; Georgi/Dimopoulos/Kaplan, 1984
Light Higgs as Pseudo-Goldstone boson ⇔ spontaneously bro-ken (approximate) global symmetry
� w/o Fine-Tuning: v ∼ Λ/4π
![Page 7: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/7.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Higgs as Pseudo-Goldstone Boson
Traditional (SUSY):Spin-Statistics =⇒ Contribu-tions from bosons and fermionscancel
Little Higgs:Global Symmetries: =⇒Quantum corrections of parti-cles of like statistics cancel
Why is the Higgs light in Little Higgs models?
Nambu-Goldstone Theorem: Spontaneous breaking of a global sym-metry leads to massless (Goldstone) boson(s) in the spectrum
Old Idea: Georgi/Pais, 1974; Georgi/Dimopoulos/Kaplan, 1984
Light Higgs as Pseudo-Goldstone boson ⇔ spontaneously bro-ken (approximate) global symmetry
� w/o Fine-Tuning: v ∼ Λ/4π
![Page 8: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/8.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Higgs as Pseudo-Goldstone Boson
Traditional (SUSY):Spin-Statistics =⇒ Contribu-tions from bosons and fermionscancel
Little Higgs:Global Symmetries: =⇒Quantum corrections of parti-cles of like statistics cancel
Why is the Higgs light in Little Higgs models?
Nambu-Goldstone Theorem: Spontaneous breaking of a global sym-metry leads to massless (Goldstone) boson(s) in the spectrum
Old Idea: Georgi/Pais, 1974; Georgi/Dimopoulos/Kaplan, 1984
Light Higgs as Pseudo-Goldstone boson ⇔ spontaneously bro-ken (approximate) global symmetry
� w/o Fine-Tuning: v ∼ Λ/4π
![Page 9: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/9.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Collective Symmetry Breaking and 3 Scale-ModelsNew Ingredience: Arkani-Hamed/Cohen/Georgi/. . . , 2001
Collective Symmetry Breaking: 2 different global symmetries,anyone unbroken⇒ Higgs exact Goldstone boson
Boson masses radiative (Coleman-Weinberg),but: Higgs protected by symmetries againstquadratic corrections @ 1-loop level mH ∼
g1
4π
g2
4πΛ
Λ
F
v
O(10 TeV)
O(1 TeV)
O(250 GeV)
� Scale Λ: global SB, newdynamics
� Scale F : Pseudo-Goldstonebosons, new vectors/fermions
� Scale v: Higgs, W/Z, `±, . . .
![Page 10: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/10.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Collective Symmetry Breaking and 3 Scale-ModelsNew Ingredience: Arkani-Hamed/Cohen/Georgi/. . . , 2001
Collective Symmetry Breaking: 2 different global symmetries,anyone unbroken⇒ Higgs exact Goldstone boson
Boson masses radiative (Coleman-Weinberg),but: Higgs protected by symmetries againstquadratic corrections @ 1-loop level mH ∼
g1
4π
g2
4πΛ
Λ
F
v
O(10 TeV)
O(1 TeV)
O(250 GeV)
� Scale Λ: global SB, newdynamics
� Scale F : Pseudo-Goldstonebosons, new vectors/fermions
� Scale v: Higgs, W/Z, `±, . . .
![Page 11: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/11.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Collective Symmetry Breaking and 3 Scale-ModelsNew Ingredience: Arkani-Hamed/Cohen/Georgi/. . . , 2001
Collective Symmetry Breaking: 2 different global symmetries,anyone unbroken⇒ Higgs exact Goldstone boson
Boson masses radiative (Coleman-Weinberg),but: Higgs protected by symmetries againstquadratic corrections @ 1-loop level mH ∼
g1
4π
g2
4πΛ
Λ
F
v
O(10 TeV)
O(1 TeV)
O(250 GeV)
� Scale Λ: global SB, newdynamics
� Scale F : Pseudo-Goldstonebosons, new vectors/fermions
� Scale v: Higgs, W/Z, `±, . . .
![Page 12: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/12.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Generic properties of Little Higgs Models
I Extended scalar (Higgs-) sector Extended global symmetry
I Specific functional form of the scalar potential
I Extended Gauge Sector: γ′, Z ′,W ′ ±
I Extended fermion sector: new heavy top: T , maybe also U,C, . . .
Example: Littlest Higgs
Arkani-Hamed/Cohen/
Katz/Nelson, 2002
m
h
ΦP
Φ±Φ±±
Φ
η
W± Z
γ′
W ′ ±Z′
T
t
U, C
![Page 13: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/13.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Generic properties of Little Higgs Models
I Extended scalar (Higgs-) sector Extended global symmetry
I Specific functional form of the scalar potential
I Extended Gauge Sector: γ′, Z ′,W ′ ±
I Extended fermion sector: new heavy top: T , maybe also U,C, . . .
Example: Littlest Higgs
Arkani-Hamed/Cohen/
Katz/Nelson, 2002
m
h
ΦP
Φ±Φ±±
Φ
η
W± Z
γ′
W ′ ±Z′
T
t
U, C
![Page 14: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/14.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Generic properties of Little Higgs Models
I Extended scalar (Higgs-) sector Extended global symmetry
I Specific functional form of the scalar potential
I Extended Gauge Sector: γ′, Z ′,W ′ ±
I Extended fermion sector: new heavy top: T , maybe also U,C, . . .
Example: Littlest Higgs
Arkani-Hamed/Cohen/
Katz/Nelson, 2002
m
h
ΦP
Φ±Φ±±
Φ
η
W± Z
γ′
W ′ ±Z′
T
t
U, C
![Page 15: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/15.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Phenomenology of Little Higgs Models
Questions:
I Constraints from past/present experiments?I What can future experiments do?I Signatures? Distinction from other models?
Low-energy effective theory ⇒ integrating out heavy degrees offreedom in path integrals, set up Power Counting: v2/F 2 Kilian/JR, 2003
I Experimental precision @ h level consistent with truncation ofexpansion at order v2/F 2
� Little Higgs Effective Field Theory: SM + Dimension 6 Operators
Constraints from contact interactions (SLC/LEP): F & c2×(4.5 TeV)
♦ Constraints evaded ⇐⇒ c� 1γ′, Z ′,W ′,± superheavy (O(Λ)) decouple from fermions
![Page 16: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/16.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Phenomenology of Little Higgs Models
Questions:
I Constraints from past/present experiments?I What can future experiments do?I Signatures? Distinction from other models?
Low-energy effective theory ⇒ integrating out heavy degrees offreedom in path integrals, set up Power Counting: v2/F 2 Kilian/JR, 2003
I Experimental precision @ h level consistent with truncation ofexpansion at order v2/F 2
� Little Higgs Effective Field Theory: SM + Dimension 6 Operators
Constraints from contact interactions (SLC/LEP): F & c2×(4.5 TeV)
♦ Constraints evaded ⇐⇒ c� 1γ′, Z ′,W ′,± superheavy (O(Λ)) decouple from fermions
![Page 17: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/17.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Phenomenology of Little Higgs Models
Questions:
I Constraints from past/present experiments?I What can future experiments do?I Signatures? Distinction from other models?
Low-energy effective theory ⇒ integrating out heavy degrees offreedom in path integrals, set up Power Counting: v2/F 2 Kilian/JR, 2003
I Experimental precision @ h level consistent with truncation ofexpansion at order v2/F 2
� Little Higgs Effective Field Theory: SM + Dimension 6 Operators
Constraints from contact interactions (SLC/LEP): F & c2×(4.5 TeV)
♦ Constraints evaded ⇐⇒ c� 1γ′, Z ′,W ′,± superheavy (O(Λ)) decouple from fermions
![Page 18: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/18.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
More Phenomenology∆S, ∆T in the Littlest Higgs modelCsáki et al./Hewett et al., 2002; Han et al.; Kilian/JR, 2003
� Mixing of (Z, γ′, Z ′), (W±,W ′ ±)
∆S/8π → 0 α∆T ∼ v2
F 2
� Higgs mass variable (UV completion)
Heavier Higgs compensates ∆T . S
T
0−0.2−0.4 0.2
−0.2
0
0.2
0.4
0.6
mH = 700GeV
400GeV250GeV
120GeV
�SM
LHM
LHM
F = 3.5 TeV
F = 4.5 TeV
Neutrino masses Kilian/JR, 2003; del Aguila et al., 2004; Han/Logan/Wang, 2005
Lepton-number violating interactions can generate neutrino masses
![Page 19: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/19.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
More Phenomenology∆S, ∆T in the Littlest Higgs modelCsáki et al./Hewett et al., 2002; Han et al.; Kilian/JR, 2003
� Mixing of (Z, γ′, Z ′), (W±,W ′ ±)
∆S/8π → 0 α∆T ∼ v2
F 2
� Higgs mass variable (UV completion)
Heavier Higgs compensates ∆T . S
T
0−0.2−0.4 0.2
−0.2
0
0.2
0.4
0.6
mH = 700GeV
400GeV250GeV
120GeV
�SM
LHM
LHM
F = 3.5 TeV
F = 4.5 TeV
Neutrino masses Kilian/JR, 2003; del Aguila et al., 2004; Han/Logan/Wang, 2005
Lepton-number violating interactions can generate neutrino masses
![Page 20: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/20.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Direct Searches
I Heavy Gauge Bosons: Resonance in e+e− → ff̄
Drell-Yan: pp/pp̄→ `+`− ⇒ Tevatron: Mγ′ & 650 GeV
O(102) lepton events @ LHC Determination of F , c
Distinction of Z ′,W ′:
Forward-Backward-Asymmetry Rosner et al., 1984; Han/Kilian/JR
I Heavy Scalars: very difficult (CLIC?)
I Heavy Top:T production @ LHC: bq → Tq′
T →W+b, th, tZ Perelstein/Peskin/Pierce, 2003
Determination of MT , Yukawa coupling
![Page 21: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/21.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Direct Searches
I Heavy Gauge Bosons: Resonance in e+e− → ff̄
Drell-Yan: pp/pp̄→ `+`− ⇒ Tevatron: Mγ′ & 650 GeV
O(102) lepton events @ LHC Determination of F , c
Distinction of Z ′,W ′:
Forward-Backward-Asymmetry Rosner et al., 1984; Han/Kilian/JR
I Heavy Scalars: very difficult (CLIC?)
I Heavy Top:T production @ LHC: bq → Tq′
T →W+b, th, tZ Perelstein/Peskin/Pierce, 2003
Determination of MT , Yukawa coupling
![Page 22: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/22.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Reconstruction of Little Higgs Kilian/JR, 2003; Han et al., 2005
� How to unravel the structureof LHM @ colliders?
� Symmetry structure⇒ Quantum Corr. Cancell.
� Nonlinear Goldstone boson structure
SIGNALS:
I Anom. Triple Gauge Couplings: WWZ, WWγ
I Anom. Higgs Coupl.: H(H)WW , H(H)ZZ
I Anom. Top Couplings: ttZ, tbW
Vectors:
I Direct Search (LHC) Mγ′/Z′ ∼ 5 TeV, c
I ILC: Contact Terms: Mγ′/Z′ ∼ 10 TeV
I Check from Triple Gauge Coupl. (ILC: per mil precision), GigaZ
Scalars:I Higgsstr., WW fusion⇒ Higgs couplings
I Higgs decays⇒ Evidence for nonlinear Goldstone nature
Include all observables in a combined fit if Little Higgs signals arefound (sufficient data from LHC and ILC)
![Page 23: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/23.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Reconstruction of Little Higgs Kilian/JR, 2003; Han et al., 2005
� How to unravel the structureof LHM @ colliders?
� Symmetry structure⇒ Quantum Corr. Cancell.
� Nonlinear Goldstone boson structure
SIGNALS:
I Anom. Triple Gauge Couplings: WWZ, WWγ
I Anom. Higgs Coupl.: H(H)WW , H(H)ZZ
I Anom. Top Couplings: ttZ, tbW
Vectors:
I Direct Search (LHC) Mγ′/Z′ ∼ 5 TeV, c
I ILC: Contact Terms: Mγ′/Z′ ∼ 10 TeV
I Check from Triple Gauge Coupl. (ILC: per mil precision), GigaZ
Scalars:I Higgsstr., WW fusion⇒ Higgs couplings
I Higgs decays⇒ Evidence for nonlinear Goldstone nature
Include all observables in a combined fit if Little Higgs signals arefound (sufficient data from LHC and ILC)
![Page 24: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/24.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Reconstruction of Little Higgs Kilian/JR, 2003; Han et al., 2005
� How to unravel the structureof LHM @ colliders?
� Symmetry structure⇒ Quantum Corr. Cancell.
� Nonlinear Goldstone boson structure
SIGNALS:
I Anom. Triple Gauge Couplings: WWZ, WWγ
I Anom. Higgs Coupl.: H(H)WW , H(H)ZZ
I Anom. Top Couplings: ttZ, tbW
Vectors:
I Direct Search (LHC) Mγ′/Z′ ∼ 5 TeV, c
I ILC: Contact Terms: Mγ′/Z′ ∼ 10 TeV
I Check from Triple Gauge Coupl. (ILC: per mil precision), GigaZ
Scalars:I Higgsstr., WW fusion⇒ Higgs couplings
I Higgs decays⇒ Evidence for nonlinear Goldstone nature
Include all observables in a combined fit if Little Higgs signals arefound (sufficient data from LHC and ILC)
![Page 25: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/25.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Reconstruction of Little Higgs Kilian/JR, 2003; Han et al., 2005
� How to unravel the structureof LHM @ colliders?
� Symmetry structure⇒ Quantum Corr. Cancell.
� Nonlinear Goldstone boson structure
SIGNALS:
I Anom. Triple Gauge Couplings: WWZ, WWγ
I Anom. Higgs Coupl.: H(H)WW , H(H)ZZ
I Anom. Top Couplings: ttZ, tbW
Vectors:
I Direct Search (LHC) Mγ′/Z′ ∼ 5 TeV, c
I ILC: Contact Terms: Mγ′/Z′ ∼ 10 TeV
I Check from Triple Gauge Coupl. (ILC: per mil precision), GigaZ
Scalars:I Higgsstr., WW fusion⇒ Higgs couplings
I Higgs decays⇒ Evidence for nonlinear Goldstone nature
Include all observables in a combined fit if Little Higgs signals arefound (sufficient data from LHC and ILC)
![Page 26: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/26.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Pseudo Axions in Little Higgs Models Kilian/Rainwater/JR, 2004
I Generically: U(1) gauged: Z ′
←→ ungauged: η, mη . 300 GeVI broken diagonal generator: η in QCD; couples to fermions as a
pseudoscalar, behaves as a axion
QCD-axion: LAx. ∼ 1ΛηGµνGρσεµνρσ
Anomalous U(1)η:
explicit symmetry breaking ⇒axion bounds not applicable
η EW singlet, couplings to SMparticles v/F suppressed
gg
bb̄
µ+µ−
cc̄
τ+τ−
γγ
Zh
50 100 150 200 250 300
10−4
0.001
0.01
0.1
1
mη [GeV]
BR [η]
![Page 27: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/27.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Pseudo Axions in Little Higgs Models Kilian/Rainwater/JR, 2004
I Generically: U(1) gauged: Z ′ ←→ ungauged: η, mη . 300 GeVI broken diagonal generator: η in QCD; couples to fermions as a
pseudoscalar, behaves as a axion
QCD-axion: LAx. ∼ 1ΛηGµνGρσεµνρσ
Anomalous U(1)η:
explicit symmetry breaking ⇒axion bounds not applicable
η EW singlet, couplings to SMparticles v/F suppressed
gg
bb̄
µ+µ−
cc̄
τ+τ−
γγ
Zh
50 100 150 200 250 300
10−4
0.001
0.01
0.1
1
mη [GeV]
BR [η]
![Page 28: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/28.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Pseudo Axions in Little Higgs Models Kilian/Rainwater/JR, 2004
I Generically: U(1) gauged: Z ′ ←→ ungauged: η, mη . 300 GeVI broken diagonal generator: η in QCD; couples to fermions as a
pseudoscalar, behaves as a axion
QCD-axion: LAx. ∼ 1ΛηGµνGρσεµνρσ
Anomalous U(1)η:
explicit symmetry breaking ⇒axion bounds not applicable
η EW singlet, couplings to SMparticles v/F suppressed
gg
bb̄
µ+µ−
cc̄
τ+τ−
γγ
Zh
50 100 150 200 250 300
10−4
0.001
0.01
0.1
1
mη [GeV]
BR [η]
![Page 29: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/29.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Little Higgs Axions at Colliders
η changes decay rates of T : Branching ratio T → tη ∼ 20− 30%
new Higgs decays: (H → Zη, H → ηη !)
I LHC: Gluon Fusion , Peak indiphoton spectrum
I ILC: associated productione+e− → tt̄η
I Photon Collider as precisionmachine for Higgs physics (schannel resonance)
WHIZARD/OMEGA:Kilian/Ohl/JR
γγ→ (H, η)→ bb̄
#evt/2 GeV
√
see = 200 GeV∫
Lee = 400 fb−1
| cos(θ)T | < 0.76
|pz|/√
see < 0.1
mη =
100 GeV
130
80 100 120 140 1600
200
400
600
800
1000
1200
1400
Minv(bb̄) [GeV]
![Page 30: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/30.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Little Higgs Axions at Colliders
η changes decay rates of T : Branching ratio T → tη ∼ 20− 30%
new Higgs decays: (H → Zη, H → ηη !)
I LHC: Gluon Fusion , Peak indiphoton spectrum
I ILC: associated productione+e− → tt̄η
I Photon Collider as precisionmachine for Higgs physics (schannel resonance)
WHIZARD/OMEGA:Kilian/Ohl/JR
γγ→ (H, η)→ bb̄
#evt/2 GeV
√
see = 200 GeV∫
Lee = 400 fb−1
| cos(θ)T | < 0.76
|pz|/√
see < 0.1
mη =
100 GeV
130
80 100 120 140 1600
200
400
600
800
1000
1200
1400
Minv(bb̄) [GeV]
![Page 31: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/31.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Little Higgs Axions at Colliders
η changes decay rates of T : Branching ratio T → tη ∼ 20− 30%
new Higgs decays: (H → Zη, H → ηη !)
I LHC: Gluon Fusion , Peak indiphoton spectrum
I ILC: associated productione+e− → tt̄η
I Photon Collider as precisionmachine for Higgs physics (schannel resonance)
WHIZARD/OMEGA:Kilian/Ohl/JR
γγ→ (H, η)→ bb̄
#evt/2 GeV
√
see = 200 GeV∫
Lee = 400 fb−1
| cos(θ)T | < 0.76
|pz|/√
see < 0.1
mη =
100 GeV
130
80 100 120 140 1600
200
400
600
800
1000
1200
1400
Minv(bb̄) [GeV]
![Page 32: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/32.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
T parity and Dark MatterI T parity: SM particles even, new ones oddI analogous to R parity in SUSY, KK parityI Bounds on f relaxed, but: pair production!I Lightest T -odd particle (LTP)⇒ Candidate for Cold Dark Matter
Littlest Higgs: γ′ LTP
Cheng/Low, 2003; Hubisz/Meade, 2005
W ′, Z ′ ∼ 650 GeVΦ ∼ 1 TeVT, T ′ ∼ 0.7-1 TeV
Annihilation:γ′γ′ → h→WW,ZZ, hh
0/10/50/70/100 600 800 1000 1200 1400 1600 1800 2000100
200
300
400
500108 144 180 216 252 288
MH(GeV)
M (GeV)AH
f
f (GeV)
I T parity Simple Group model: Pseudo-Axion η LTPKilian/Rainwater/JR/Schmaltz
![Page 33: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/33.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
T parity and Dark MatterI T parity: SM particles even, new ones oddI analogous to R parity in SUSY, KK parityI Bounds on f relaxed, but: pair production!I Lightest T -odd particle (LTP)⇒ Candidate for Cold Dark Matter
Littlest Higgs: γ′ LTP
Cheng/Low, 2003; Hubisz/Meade, 2005
W ′, Z ′ ∼ 650 GeVΦ ∼ 1 TeVT, T ′ ∼ 0.7-1 TeV
Annihilation:γ′γ′ → h→WW,ZZ, hh
0/10/50/70/100 600 800 1000 1200 1400 1600 1800 2000100
200
300
400
500108 144 180 216 252 288
MH(GeV)
M (GeV)AH
f
f (GeV)
I T parity Simple Group model: Pseudo-Axion η LTPKilian/Rainwater/JR/Schmaltz
![Page 34: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/34.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
T parity and Dark MatterI T parity: SM particles even, new ones oddI analogous to R parity in SUSY, KK parityI Bounds on f relaxed, but: pair production!I Lightest T -odd particle (LTP)⇒ Candidate for Cold Dark Matter
Littlest Higgs: γ′ LTP
Cheng/Low, 2003; Hubisz/Meade, 2005
W ′, Z ′ ∼ 650 GeVΦ ∼ 1 TeVT, T ′ ∼ 0.7-1 TeV
Annihilation:γ′γ′ → h→WW,ZZ, hh
0/10/50/70/100 600 800 1000 1200 1400 1600 1800 2000100
200
300
400
500108 144 180 216 252 288
MH(GeV)
M (GeV)AH
f
f (GeV)
I T parity Simple Group model: Pseudo-Axion η LTPKilian/Rainwater/JR/Schmaltz
![Page 35: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/35.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005
Conclusions
Little Higgs elegant alternative to SUSYGlobal Symmetry structure stabilizes the Electroweak scale
I Generics: new heavy gauge bosons, scalars, quarks
Little Higgs predicts higher Higgs masses MH ∼ 300− 400 GeV
� UV embedding, GUT, Flavor ?
I New developments: Neutrino masses, T -parity, LH Dark Matter,Pseudo-Axions
Strategy for Reconstruction at COLLIDER EXPERIMENTSdirect search LHC (ILC) ←→ precision observables ILC (LHC)
![Page 36: The Big Deal with the Little Higgs - DESYreuter/downloads/biglittle.pdf · J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005 The Big Deal with the Little Higgs Jürgen](https://reader030.vdocuments.net/reader030/viewer/2022041216/5e059855f3feb6561362d7fb/html5/thumbnails/36.jpg)
J. Reuter The Big Deal with the Little Higgs Edinburgh, 8.12.2005