[PPT] - Introduction to the Standard Model of ElectroWeak interactions PowerPoint Presentation

SLIDE 1

Introduction to the Standard Model of ElectroWeak interactions

Pietro Slavich

(LPTHE Paris)

SLIDE 2

Prelude: the four fundamental interactions

Electromagnetic:
Weak:
Strong:
Gravity:
governs atomic physics (and beyond)
long range, V(r) ~ 1/ r
carried by massless bosons (photons)
described as gauge theory (QED)
governs radioactive decays of nucleons
short range, V(r) ~ e-mr/ r
carried by massive bosons (W±, Z)
described as effective 4-fermion theory
governs interactions within nucleons
confined, V(r) ~ r (at large r )
carried by massless bosons (gluons)
described as gauge theory (QCD)
interactions between massive bodies
long range, V(r) ~ 1/ r , but very weak
described as geometry of space-time

SLIDE 3

Prelude: the four fundamental interactions

Electromagnetic:
Weak:
Strong:
Gravity:
governs atomic physics (and beyond)
long range, V(r) ~ 1/ r
carried by massless bosons (photons)
described as gauge theory (QED)
governs radioactive decays of nucleons
short range, V(r) ~ e-mr/ r
carried by massive bosons (W±, Z)
described as effective 4-fermion theory
governs interactions within nucleons
confined, V(r) ~ r (at large r )
carried by massless bosons (gluons)
described as gauge theory (QCD)
interactions between massive bodies
long range, V(r) ~ 1/ r , but very weak
described as geometry of space-time

                          

ElectroWeak interaction: unified description as spontaneously broken gauge theory

SLIDE 4

Fermilab 1995

SLIDE 5

Outline of the lectures

1) The origin of particle masses in the SM 2) The hunt for the Higgs boson 3) Beyond the Standard Model [?]

SLIDE 6

I ) The origin of particle masses in the SM

SLIDE 7

e.g., for a fermion field:

ψ(x) → U(x) ψ(x) , U(x) = exp [ iαa(x) T a]

We must build a covariant derivative such that

Dµ (U ψ) = U (Dµ ψ) Dµ ≡ ∂µ − i g V a

µ T a

If the vector field transforms as

V a

µ (x) T a → U(x)

V a

µ (x) T a + i

g ∂µ ⇥ U †(x)

then the kinetic term is invariant:

¯ ψ(x) γµ Dµ ψ → ¯ ψ(x) U † U γµ (Dµ ψ)

Defining the field strength tensor as:

F a

µν

= ∂µV a

ν − ∂νV a µ + g fabc V b µV c ν

The gauge-invariant kinetic term for the vector boson is

−1 4 F µν a F a

µν

Alone, the kinetic term is not invariant:

¯ ψ γµ ∂µ ψ → ¯ ψ U † γµ∂µ (U ψ)

Local gauge invariance

SLIDE 8

e.g., for a fermion field:

ψ(x) → U(x) ψ(x) , U(x) = exp [ iαa(x) T a]

We must build a covariant derivative such that

Dµ (U ψ) = U (Dµ ψ) Dµ ≡ ∂µ − i g V a

µ T a

If the vector field transforms as

V a

µ (x) T a → U(x)

V a

µ (x) T a + i

g ∂µ ⇥ U †(x)

then the kinetic term is invariant:

¯ ψ(x) γµ Dµ ψ → ¯ ψ(x) γµ Dµ ψ

Defining the field strength tensor as:

F a

µν

= ∂µV a

ν − ∂νV a µ + g fabc V b µV c ν

The gauge-invariant kinetic term for the vector boson is

−1 4 F µν a F a

µν

Alone, the kinetic term is not invariant:

¯ ψ γµ ∂µ ψ → ¯ ψ U † γµ∂µ (U ψ)

Local gauge invariance

SLIDE 9

e.g., for a fermion field:

ψ(x) → U(x) ψ(x) , U(x) = exp [ iαa(x) T a]

We must build a covariant derivative such that

Dµ (U ψ) = U (Dµ ψ) Dµ ≡ ∂µ − i g V a

µ T a

If the vector field transforms as

V a

µ (x) T a → U(x)

V a

µ (x) T a + i

g ∂µ ⇥ U †(x)

then the kinetic term is invariant:

¯ ψ(x) γµ Dµ ψ → ¯ ψ(x) γµ Dµ ψ

Defining the field strength tensor as:

F a

µν

= ∂µV a

ν − ∂νV a µ + g fabc V b µV c ν

The gauge-invariant kinetic term for the vector boson is

−1 4 F µν a F a

µν

T a, T b⇥

= i f abc T c

Alone, the kinetic term is not invariant:

¯ ψ γµ ∂µ ψ → ¯ ψ U † γµ∂µ (U ψ)

Local gauge invariance

SLIDE 10

e.g., for a fermion field:

ψ(x) → U(x) ψ(x) , U(x) = exp [ iαa(x) T a]

We must build a covariant derivative such that

Dµ (U ψ) = U (Dµ ψ) Dµ ≡ ∂µ − i g V a

µ T a

If the vector field transforms as

V a

µ (x) T a → U(x)

V a

µ (x) T a + i

g ∂µ ⇥ U †(x)

then the kinetic term is invariant:

¯ ψ(x) γµ Dµ ψ → ¯ ψ(x) γµ Dµ ψ

Defining the field strength tensor as:

F a

µν

= ∂µV a

ν − ∂νV a µ + g fabc V b µV c ν

The gauge-invariant kinetic term for the vector boson is

−1 4 F µν a F a

µν

Alone, the kinetic term is not invariant:

¯ ψ γµ ∂µ ψ → ¯ ψ U † γµ∂µ (U ψ)

Local gauge invariance

SLIDE 11

GSM ≡ SU(3)C × SU(2)L × U(1)Y

Each subgroup is characterized by its own coupling constant and vector bosons

(a = 1 . . . 8) (i = 1 . . . 3)

The Standard Model is based on local gauge invariance w.r.t. the group

The gauge sector of the Standard Model

Group charge coupling boson SU(3)C color

gS

Gµ SU(2)L weak isospin

g

Wµ U(1)Y hypercharge

g’

Bµ

a i

SLIDE 12

Gauge invariance fixes the Yang-Mills part of the SM Lagrangian

LYM = − 1 4 Gµν aGa

µν − 1

4 W µν iW i

µν − 1

4 BµνBµν Ga

µν

= ∂µGa

ν − ∂νGa µ + gS fabc Gb µGc ν

W i

µν

= ∂µW i

ν − ∂νW i µ + g fijk W j µW k ν

Bµν = ∂µBν − ∂νBµ

This determines the kinetic terms and the self-interactions of the gauge bosons

g , gS

V V V V V V V

g2 , g2

S

SLIDE 13

The fermions come in three generations and belong to different representations of GSM qi

L ≡

  ui

L

di

L

  ∼ (3, 2, +1/6) , `i

L ≡

  ⌫i

L

ei

L

  ∼ (1, 2, −1/2) , ui

R ∼ (3, 1, +2/3) ,

di

R ∼ (3, 1, −1/3) ,

ei

R ∼ (1, 1, −1)

(i = 1 . . . 3)

Gauge invariance also fixes the interaction of the fermions with the gauge bosons

ui =   u c t   , di =   d s b   , ei =   e µ τ   , νi =   νe νµ ντ  

The flavors of quarks and leptons are:

V g′, g, gS f f

LF = i ¯ Ψ γµ Dµ Ψ Dµ = ∂µ − i gS Ga

µ λa − i g W i µ T i − i g Bµ Y

SLIDE 14

The electromagnetic group is contained in U(1)em SU(2)L × U(1)Y Rotate the neutral gauge fields:

Bµ = Aµ cos θW − Zµ sin θW W 3

µ

= Aµ sin θW + Zµ cos θW L ⊃ ¯ Ψ γµ g sin θW T 3 + g cos θW Y ⇥ Ψ Aµ + ¯ Ψ γµ g cos θW T 3 − g sin θW Y ⇥ Ψ Zµ

The first term corresponds to the electromagnetic interaction if:

e ¯ Ψ γµ Q Ψ Aµ Q = T 3 + Y , g sin θW = g cos θW = e

Long before the weak bosons were found, the strength of the interactions they mediate (e.g. muon decay) suggested that they must have masses of the order of 100 GeV is the photon; the weak gauge bosons are and

Z W ± = 1 ⇥ 2

W 1 W 2⇥

A

Also, quark and leptons have masses ranging from ~ MeV to 170 GeV

SLIDE 15

Mass terms for fermions and vector bosons break the gauge symmetry of the Lagrangian

mψ ¯ ψψ = mψ ¯ ψLψR + ¯ ψRψL ⇥ , ψL,R = PL,R ψ = 1 γ5 2 ψ

Also, mass terms for the vector bosons make the theory non-renormalizable... ...and they violate the unitarity of the scattering matrix. E.g., consider V V scattering: and belong to different representations of the gauge group (chiral fermions) ψL ψR

Lmass = − mψ ¯ ψψ + 1 2 m2

V V µaV a µ

+ + . . .

M ∝ s m2

V

for s m2

V

The problem with particle masses

k → ∞

∆µν = i k2 − m2

V

−gµν + kµ kν

m2

V

−

→ const

SLIDE 16

The Higgs mechanism

SLIDE 17

The Brout-Englert-Higgs (BEH) mechanism

SLIDE 18

The Anderson-Higgs mechanism

SLIDE 19

The LGABEHGHKMPWS’tH mechanism

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The Higgs mechanism

SLIDE 21

The Higgs mechanism and the Higgs boson

SLIDE 22

Consider a single complex scalar with a “mexican hat” potential (Goldstone model) The potential has an infinite number of equivalent minima for |φ|2 = −m2

2 λ

The system will choose one specific minimum, breaking the global rotational symmetry

Spontaneous symmetry breaking

The Lagrangian of the theory respects a symmetry, but the vacuum state breaks it

m2 < 0 , λ > 0 φ ≡ 1 √ 2 (φ1 + i φ2) , L = ∂µφ∗ ∂µφ − V (φ) , V (φ) = m2 |φ|2 + λ |φ|4

SLIDE 23

E.g., we can expand the scalar field around a real vacuum expectation value (vev) At the minimum of the scalar potential (= the vacuum state) we have φ⇥ =

v ⇤ 2

Up to an irrelevant constant, the scalar potential becomes

V = (m2v + λv3) H + 1 2 (m2 + 3λv2) H2 + 1 2 (m2 + λv2) G2 +λv H(H2 + G2) + λ 4 (H2 + G2)2 φ ≡ 1 √ 2 [v + H(x) + i G(x)] , v =

−m2

λ m2

H = −2 m2 = 2 λ v2 ,

m2

G = 0

Inserting the value of the linear term vanishes, and the masses of the scalars become

v

G is the Goldstone boson associated with the spontaneous breaking of a continuous global symmetry

SLIDE 24

The Higgs mechanism: spontaneous breaking of a local symmetry

Consider a U(1) gauge theory with a complex scalar field (scalar QED) L = − 1 4 FµνF µν + 1 2 e2 v2 BµBµ + e2 v HBµBµ + 1 2 e2 H2BµBµ + 1 2∂µH∂µH − V (H) Bµ ≡ Aµ − 1 e ∂µθ is gauge invariant, and Fµν = ∂µAν − ∂νAµ = ∂µBν − ∂νBµ In this “unitary gauge”, the massless field Aµ “eats” the phase and becomes the massive field Bµ (Dµ = ∂µ − i e Aµ) L = − 1 4 FµνF µν + (Dµφ)∗Dµφ − m2 |φ|2 − λ |φ|4 The remaining scalar H is also massive, and interacts with the gauge field Parameterize the complex scalar as modulus and phase: φ = ρ ei θ L = − 1 4 FµνF µν + ρ2 (∂µθ − e Aµ)2 + ∂µρ ∂µρ − m2 ρ2 − λ ρ4 Again, for m2 < 0 and > 0 the symmetry is broken and the scalar gets a vev

λ

ρ = 1 √ 2 (v + H)

SLIDE 25

Spontaneous breaking of the SU(2)xU(1) gauge symmetry

Φ ≡

ϕ+

ϕ0 ⇥ ∼ (1, 2, +1/2)

Introduce a SU(2) doublet of complex scalars: The kinetic term determines the interactions between scalars and gauge bosons:

g , g′

V Φ V V

g2 , g′ 2

Φ Φ Φ

If m2 < 0 and > 0 the mexican-hat potential induces a vev v for the doublet

λ LS = (DµΦ)† (DµΦ) − m2 Φ†Φ − λ (Φ†Φ)2

Dµ = ∂µ − i g

2 W i

µ τ i − i g

2 Bµ

SLIDE 26

Gauge symmetry allows us to rotate away the via a SU(2) transformation (unitary gauge)

θi V = 1 2(2λv2)H2 + λvH3 + 1 4λH4

The kinetic term for the doublet contains mass and interaction terms for the weak gauge bosons

(DµΦ)† (DµΦ) = 1 2∂µH∂µH + 1 4 g2 W µ +W

µ + 1

8(g2 + g⇥2)ZµZµ ⇥ (v + H)2

W ±, Z

g2 , g′ 2

W ±, Z

v v

m2

W = 1

4 g2 v2 m2

Z = 1

4(g2 + g2) v2

(the photon remains massless) Note: m2

W

m2

Z cos2 θW

= 1 We can parameterize the complex doublet as:

Φ = 1 √ 2 ei τ i θi(x)

v + H(x)

SLIDE 27

The value of can be related to the constant in the low-energy effective Lagrangian (four-fermion interaction) that describes the muon decay process

v

GF µ− − → e− νµ νe In the Standard Model the muon decay is mediated by the exchange of a W boson

Leff ⊃ − GF √ 2 νµ γα (1 − γ5) µ e γα (1 − γ5) νe A = − 4 GF √ 2 , Γ = G2

F m5 µ

192 π3 + O(m2

e/m2 µ)

µ νµ e νe GF µ νµ νe e W − g g

A ⇥

g2

2 m2

W

Equating the amplitudes and inserting we get: mW = g v 2 v = ( ⇥ 2 GF )−1/2 246 GeV This also allows us to derive another relation among measurable quantities: m2

W (1 − m2 W /m2 Z) =

π α √ 2GF

SLIDE 28

+ + + . . .

H

The inclusion of diagrams with exchange of a scalar H restores the unitarity of V V scattering at high energy:

M ∝ m2

H

v2

The scalar mass cuts off the divergence. But unitarity is again at risk if mH is too large Unitarity conditions on the partial-wave decomposition of the amplitude:

M = 16⇡

∞

X

`=0

(2` + 1) P`(cos ✓) a` |Re(a`)| < 1 2 a0(WLWL − → WLWL) ≈ − m2

H

8π v2

For Thus, mH < 870 GeV (even stronger bounds by considering several processes at once)

m2

W ⌧ m2 H ⌧ s

SLIDE 29

Counting the bosonic degrees of freedom in the unbroken and broken phases: The degrees of freedom corresponding to the three would-be-Goldstone bosons have been absorbed in the longitudinal components of the massive vector fields broken symmetry: One real scalar : the Higgs boson Three massive vector bosons One massless vector boson (H) (Z , W +, W −)

(γ)

1+(3x3)+2 = 12 d.o.f.

                  

unbroken symmetry: 4+(4x2) = 12 d.o.f. (B , W i) A complex doublet Four massless vector bosons

(Φ)

  

The renormalizability of the theory is still hidden in this unitary gauge, but it becomes manifest with different gauge choices (‘t Hooft, 1971)

SLIDE 30

Unitary gauge: (no would-be-Goldstone boson) Renormalizable gauge:

∆µν = i k2 − m2

V

−gµν + (1 − ξ)

kµ kν k2 − ξm2

V

∆G

= i k2 − ξm2

V

∆µν = i k2 − m2

V

−gµν + kµ kν

m2

V

The contributions of the unphysical would-be-Goldstone boson combine with

those of the gauge boson, and we find the same results as in the unitary gauge The propagator of the massive vector boson depends on the choice of gauge: (also, predictions for physical observables must not depend on the arbitrary parameter ) ξ

SLIDE 31

Fermion masses and flavor mixing

qi

L ≡

  ui

L

di

L

  ∼ (3, 2, +1/6) , ui

R ∼ (3, 1, +2/3) ,

di

R ∼ (3, 1, −1/3)

We can generate the quark masses by building gauge-invariant interactions with the Higgs

Φ ∼ (1, 2, +1/2) , ⇤ Φ ≡ Φ∗ =

⇥0 ∗

−⇥− ⇥ ∼ (1, 2, −1/2)

dR uL ϕ+ ϕ− uR dL Yd Yu ϕ0 dL dR Yd ϕ0 uR uL Yu

LY = − (YD)ij qi

L Φ dj R − (YU)ij qi L

Φ uj

R

+ h.c.

SLIDE 32

Fermion masses and flavor mixing

qi

L ≡

  ui

L

di

L

  ∼ (3, 2, +1/6) , ui

R ∼ (3, 1, +2/3) ,

di

R ∼ (3, 1, −1/3)

We can generate the quark masses by building gauge-invariant interactions with the Higgs

Φ ∼ (1, 2, +1/2) , ⇤ Φ ≡ Φ∗ =

⇥0 ∗

−⇥− ⇥ ∼ (1, 2, −1/2)

dR uL ϕ+ ϕ− uR dL Yd Yu dL dR Yd uR uL Yu v v

LY = − (YD)ij qi

L Φ dj R − (YU)ij qi L

Φ uj

R

+ h.c.

SLIDE 33

The matrices of Yukawa couplings can be diagonalized by bi-unitary transformations

diag(Yu, Yc, Yt) = V †

u YU Uu ,

diag(Yd, Ys, Yb) = V †

d YD Ud

Applying the same rotations to the quark fields:

uL → Vu uL , uR → Uu uR , dL → Vd dL , dR → Ud dR

the Yukawa interaction Lagrangian becomes (in the unitary gauge):

LY = − 1 √ 2 (v + H)

Yu ¯

uu + Yc ¯ cc + Yt ¯ tt + Yd ¯ dd + Ys ¯ ss + Yb ¯ bb ⇥

Therefore the masses of the quarks are:

mq = Yq v √ 2

SLIDE 34

The neutral current couplings of the quarks to photon and Z are not affected by the rotation

L ⊃ ⇤

qi

ei

qi

L γµ qi L + qi R γµ qi R

⇥ Aµ + ⇤

qi

gi

L qi L γµ qi L + gi R qi R γµ qi R

⇥ Zµ

On the other hand, the charged current couplings of the quarks to the W boson are affected:

L ⊃

i

g √ 2 ui

L γµ di L W + µ

+ h.c. − →

i,j

g √ 2 ui

L γµ V

CKM

ij

dj

L W + µ

+ h.c.

Therefore, charged interactions mix quarks of different flavor (neutral interactions don’t)

V

CKM

ij

≡ V †

u Vd

is the so-called Cabibbo-Kobayashi-Maskawa matrix The CKM matrix can be represented in terms of four independent parameters (e.g., three independent rotation angles and one complex phase)

uL γµ uL − → uL V †

u γµ Vu uL = uL γµ uL

e.g. (and so on)

SLIDE 35

A large number of flavor-violating processes allow for the determination

f the Wolfenstein parameters ¯

ρ, ¯ η The good agreement between many different measurements provides a consistency check of the CKM picture An alternative representation of the CKM matrix is the so-called “Wolfenstein parametrization”:

V

CKM =

  1 − λ2

2

λ Aλ3(ρ − iη) −λ 1 − λ2

2

Aλ2 Aλ3(1 − ρ − iη) −Aλ2 1   + O(λ4)

(plot from UTfit collaboration)

1
0.5

0.5 1

1
0.5

0.5 1

)
+
sin(2

s

m

d

m

d

m

K
cb

V

ub

V )

BR(B

Summer14

SM fit

SLIDE 36

Among the SM leptons, there are no :

νi

R

li

L ≡

  νi

L

ei

L

  ∼ (1, 2, −1/2) , ei

R ∼ (1, 1, −1)

The only gauge-invariant Yukawa interaction that we can build gives a mass term for charged leptons:

LY = − (YE)ij li

L Φ ej R

+ h.c.

Again, we can diagonalize the Yukawa matrix with a bi-unitary transformation

diag(Ye, Yµ, Yτ) = V †

e YE Ue ,

ml = Yl v √ 2

but now we are free to rotate the parallel to the :

νL eL νL → Ve νL , eL → Ve eL , eR → Ue eR

Therefore, the charged interaction does not mix leptons of different flavors:

L ⊃

i

g √ 2 νi

L γµ ei L W + µ

+ h.c. − →

itself

SLIDE 37

Flavor oscillations in solar, atmospheric, and accelerator-produced neutrinos provide evidence of flavor mixing and (tiny) masses (the first clear sign of Beyond-the-SM physics!!!) This can be fixed by introducing “sterile” right-handed neutrinos: N i

R ∼ (1, 1, 0)

Then, gauge symmetry allows for both a Yukawa interaction and a “Majorana” mass term:

LY = − h (YE)ij li

L Φ ej R + (YN)ij li L e

Φ N j

R

+ h.c. i − 1 2 Mij N i

R N j R

After EWSB, the mass matrix for the neutrinos becomes (schematically):

L ⊃ −

νL NR

✓ mD mD M ◆ ✓ νL NR ◆

with

mD = YN v √ 2

For M >> mD , this gives both light, almost-left neutrinos and heavy, almost-right neutrinos:

mν ≈ m2

D

M , mN ≈ M

Introducing heavy sterile neutrinos does not affect SM phenomenology at the weak scale (seesaw mechanism)

SLIDE 38

Flavor oscillations in solar, atmospheric, and accelerator-produced neutrinos provide evidence of flavor mixing and (tiny) masses (the first clear sign of Beyond-the-SM physics!!!) This can be fixed by introducing “sterile” right-handed neutrinos: N i

R ∼ (1, 1, 0)

Then, gauge symmetry allows for both a Yukawa interaction and a “Majorana” mass term:

LY = − h (YE)ij li

L Φ ej R + (YN)ij li L e

Φ N j

R

+ h.c. i − 1 2 Mij N i

R N j R

After EWSB, the mass matrix for the neutrinos becomes (schematically):

L ⊃ −

νL NR

✓ mD mD M ◆ ✓ νL NR ◆

with

mD = YN v √ 2

For M >> mD , this gives both light, almost-left neutrinos and heavy, almost-right neutrinos:

mν ≈ m2

D

M , mN ≈ M

Introducing heavy sterile neutrinos does not affect SM phenomenology at the weak scale (seesaw mechanism)

Tape-cul

SLIDE 39

Constraints on non-minimal Higgs sectors

A single SU(2) doublet is the minimal option. Several scalars could contribute to EWSB However, constraints from precision observables, e.g.: ρ ≡ m2

W

m2

Z cos2 θW

≈ 1 The contribution to the rho parameter from a given Higgs field depends on its SU(2) properties: L ⊃ 1 2 m2

W

W 1µW 1

µ + W 2µW 2 µ

+ 1

2 (W µ

3 Bµ )

 M 2 M 0 2 M 0 2 M 00 2 ✓ W3µ Bµ ◆ mγ = 0 − → tan θW = M 00 M , m2

Z = M 2 + M 00 2

− → ρ = m2

W

M 2 Doublets are OK. Other SU(2) representations would change rho (then vi must be small! ) For a set of Higgs fields :

Φi

ρ = P

i v2 i

⇥ Ii (Ii + 1) − (I3i)2⇤ 2 P

i v2 i (I3i)2

SLIDE 40

The simplest non-minimal case: two-Higgs-doublet model

Two complex SU(2) doublets => 8 degrees of freedom: Φi =   ϕ+

i 1 √ 2(vi + ϕR i + i ϕI i)

 

H

h

=
cos α

sin α − sin α cos α ϕR

1

ϕR

2

If the potential does not break CP, the neutral states

are one pseudoscalar and two scalars ( ) h , H A 5 physical states (3 neutral, 2 charged ) and 3 would-be-Goldstone bosons ( ) H± G0 , G± After EWSB: V = m2

11Φ† 1Φ1 + m2 22Φ† 2Φ2 −

h m2

12Φ† 1Φ2 + h.c.

i +λ1 2 (Φ†

1Φ1)2 + λ2

2 (Φ†

2Φ2)2 + λ3 (Φ† 1Φ1)(Φ† 2Φ2) + λ4 (Φ† 1Φ2)(Φ† 2Φ1)

+ ⇢λ5 2 (Φ†

1Φ2)2 +

h λ6 (Φ†

1Φ1) + λ7 (Φ† 2Φ2)

i (Φ†

1Φ2) + h.c.

SLIDE 41

Generating particle masses in many-Higgs-doublet models

The gauge-boson masses receive a contribution from each Higgs vev Also, each Higgs doublet has its own set of matrices for the couplings to the fermions: Rotating the fields to a basis where one Higgs ( ) gets the vev and the others ( ) don’t

ΦSM Φi

In general, the matrices are not diagonal in the basis where are diagonal

yU,D

i

Y U,D

The non-SM doublets mediate Flavor-Changing Neutral Currents!!! −LY =

i

¯ qL Φi yU

i uR +

i

¯ qL Φi yD

i dR ,

M U,D =

i

yU,D

i

vi −LY = ¯ qL ΦSM Y UuR + ¯ qL ΦSM Y DdR +

i

¯ qL Φi yU

i uR +

i

¯ qL Φi yD

i dR

m2

W = g2

4

i

v2

i ,

m2

Z = g2 + g 2

4

i

v2

i

SLIDE 42

Natural Flavor Conservation: FCNC in Higgs-quark interactions are absent when

nly one doublet couples to each species of quarks

Minimal Flavor Violation: FCNC can be suppressed if the matrices of non-SM Higgs couplings are made up of combinations of YU and YD e.g., in THDMs: (Type I) (Type II) −LY = ¯ qL Φ1 Y UuR + ¯ qL Φ1 Y DdR −LY = ¯ qL Φ2 Y UuR + ¯ qL Φ1 Y DdR yU

i = Ai u

1 + u Y UY U † + . . .
Y U ,

yD

i = Ai d

1 + d Y UY U † + . . .
Y D

Only two sets of SU(3)xSU(2)xU(1) quantum numbers are allowed for an additional scalar whose Yukawa couplings transform like YU and YD under rotations in flavor space

(1,2)1/2 (8,2)1/2

The usual THDMs The additional scalar is a color octet (Manohar & Wise, hep-ph/0606172) So far, no additional Higgs bosons did show up at colliders (nor did they manifest through contributions to flavor or EW observables)

SLIDE 43

Natural Flavor Conservation: FCNC in Higgs-quark interactions are absent when

nly one doublet couples to each species of quarks

Minimal Flavor Violation: FCNC can be suppressed if the matrices of non-SM Higgs couplings are made up of combinations of YU and YD e.g., in THDMs: (Type I) (Type II) −LY = ¯ qL Φ1 Y UuR + ¯ qL Φ1 Y DdR −LY = ¯ qL Φ2 Y UuR + ¯ qL Φ1 Y DdR yU

i = Ai u

1 + u Y UY U † + . . .
Y U ,

yD

i = Ai d

1 + d Y UY U † + . . .
Y D

Only two sets of SU(3)xSU(2)xU(1) quantum numbers are allowed for an additional scalar whose Yukawa couplings transform like YU and YD under rotations in flavor space

(1,2)1/2 (8,2)1/2

The usual THDMs The additional scalar is a color octet (Manohar & Wise, hep-ph/0606172) So far, no additional Higgs bosons did show up at colliders (nor did they manifest through contributions to flavor or EW observables)

b s t γ

H+ Z

t t b b

H+

SLIDE 44

Interlude: who ordered this particle?

Three PRL papers in 1964 described the mechanism that gives mass to gauge bosons: (does not mention a physical scalar) (cites BE , mentions a massive scalar as an essential feature of the mechanism) (cites BE and H, mentions a scalar which is massless and decoupled) Then Weinberg (1967) and Salam (1968) incorporated the mechanism in the EW theory and ‘t Hooft (1971) proved that spontaneously broken gauge theories are renormalizable

SLIDE 45

“Nobelitis”

Five authors alive,

nly three Nobel slots...

Symmetry breaking and the Scalar boson

evolving perspectives1

Fran¸ cois Englert

Service de Physique Th´ eorique Universit´ e Libre de Bruxelles, Campus Plaine, C.P.225

SLIDE 46

The ending was unexciting... ...but some people just wouldn’t let go:

“(...) the Nobel Committee [5] stated ‘The Goldstone theorem holds in the sense that that Nambu-Goldstone mode is there but it gets absorbed into the third component of a massive vector field.’ (...) It is shown in what follows that that is not a valid view and that a massless gauge particle necessarily remains in the theory.”

[arXiv:1401.6924]

SLIDE 47

II) The hunt for the Higgs boson

SLIDE 48

The main contenders:

Large Electron-Positron Collider (LEP) at CERN (1989-2000):

circular e+e- collider, center-of-mass energy up to 209 GeV;

Tevatron at Fermilab (1983-2012):

circular pp collider, c.o.m. energy up to 2 TeV;

Large Hadron Collider (LHC) at CERN (2011-2012, 2015-? ):

circular pp collider, c.o.m. energy up to 8 TeV (designed for 14 TeV). _

SLIDE 49

H

q, ℓ γ γ (Z)

H

+

γ

W

γ (Z)

Higgs boson couplings to the other SM particles

The interaction Lagrangian contains (v + H), thus HPP couplings are controlled by mP / v Feynman rules: H ¯ ff : i mf v , H W +

µ W − ν

: 2 i m2

W

v gµν , H ZµZν : 2 i m2

Z

v gµν , HH W +

µ W − ν

: 2 i m2

W

v2 gµν , HH ZµZν : 2 i m2

Z

v2 gµν (among fermions, only top, bottom and tau have sizable couplings to the Higgs) Loops of charged particles also induce Higgs-boson couplings to gluons and photons:

H

q g g

(in practice, only the top, bottom and W contributions to the loops are relevant)

L ⊃ − Cg αs 8 π v H Ga µνGa

µν

− Cγ α 8 π v H AµνAµν − CγZ α 8 π v H AµνZµν

SLIDE 50

[GeV]

H

M 100 200 300 400 500 1000 Higgs BR + Total Uncert

3

10

2

10

1

10 1

LHC HIGGS XS WG 2011

b b

c

c t t gg

Z

WW ZZ

The decay rates of the Higgs boson depend only on its mass (the couplings are all fixed) Decays to bottom quarks dominate at low mass, then WW (and ZZ) for mH > 140 GeV Decays to two photons are loop-suppressed but easy to detect

SLIDE 51

LEP & Tevatron corner it

SLIDE 52

Higgs boson production at e+e- colliders

The dominant processes are Higgs-strahlung and WW fusion:

e− e+ Z Z H νe e+ H ¯ νe e−

W − W +

✓ Well-defined energy and momentum in the initial state ✓ “Clean” experimental environment (no QCD background) ✓ Allows for precision studies of the Higgs boson properties (couplings, spin, parity...)

The cross section is small and it decreases with energy, high luminosity required
Synchrotron radiation makes circular machines unpractical above LEP2 energy

✦ The International Linear Collider (~500 GeV) could be the next Higgs factory

SLIDE 53

At LEP, the dominant channel was Higgs-strahlung followed by decay in bottom or tau pairs

10

6

10

5

10

4

10

3

10

2

10

1

1 100 102 104 106 108 110 112 114 116 118 120

mH(GeV/c2) CLs

114.4 115.3

LEP

Observed Expected for background

10

2

10

1

1 20 40 60 80 100 120

mH(GeV/c2) 95% CL limit on 2

LEP

s = 91-210 GeV

Observed Expected for background

(a)

(CLs = CLs+b / CLb) ξ2 = (gHZZ/gSM

HZZ)2

mH > 114.4 GeV

SLIDE 54

LEP’s parting shot: ~ 1.7 excess for mH ≈ 115 GeV

σ

1 2 3 4 5 6 7 20 40 60 80 100 120

mHrec (GeV/c2) Events / 3 GeV/c2

LEP Tight

s

– = 200-209 GeV

Data Background Signal (115 GeV/c2) Data 18 Backgd 14 Signal 2.9 all > 109 GeV/c2 4 1.2 2.2

Was it the real thing? People kept arguing about it until the start of the LHC...

SLIDE 55

Higgs boson production at hadron colliders

q ¯ q V V H q q H q q

V V

Higgs-strahlung VBF

H

g g t, b g g t, b

H

t, b

gluon fusion associated prod. with top/bottom

✓ Synchrotron radiation negligible: high energies viable with circular machines ✓ Colored particles in initial state: large cross section due to the strong interaction

Energy and momentum of the initial-state partons not known event-by-event (PDFs)
Large QCD backgrounds, “messy” experimental environment

SLIDE 56

Gluon fusion is the dominant production mechanism both at the Tevatron and the LHC
VBF is the second-largest mechanism and can be easily separated from the background
Higgs-strahlung is the main channel for light Higgs at the Tevatron
Associated Higgs production with a top pair is rare and has difficult backgrounds

[GeV]

H

M 80 100 200 300 400 1000 H+X) [pb] → (pp σ

2

10

1

10 1 10

2

10 = 8 TeV s

LHC HIGGS XS WG 2012

H ( N N L O + N N L L Q C D + N L O E W ) → p p q q H ( N N L O Q C D + N L O E W ) → p p WH (NNLO QCD + NLO EW) → pp ZH (NNLO QCD +NLO EW) → pp ttH (NLO QCD) → pp

LHC

SLIDE 57

Tevatron experiments did their best, but it wasn’t enough

Excluded at 95% CL: 147 GeV < mH < 180 GeV Broad excess (mostly from bb) for 115 GeV < mH < 140 GeV

1 10 100 110 120 130 140 150 160 170 180 190 200 1 10 mH (GeV/c2) 95% CL Limit/SM

Tevatron Run II Preliminary, L 10.0 fb-1 Observed Expected w/o Higgs ±1 s.d. Expected ±2 s.d. Expected Tevatron Exclusion Tevatron Exclusion SM=1

June 2012

SLIDE 58

Constraints on the Higgs mass from EW precision observables

fine-structure constant

(from Thomson scattering)

Fermi coupling constant

(from muon decay)

Z-boson mass

(from LEP data)

leptonic width of the Z

(from LEP data)

W-boson mass

(from LEP+Tevatron data)

effective leptonic Weinberg

angle (from LEP+SLC data) α = 1/137.03599911(46) GF = 1.16637(1) × 10−5 GeV−2 mZ = 91.1876(21) GeV Γ+− = 83.984(86) MeV ALR ≡ σL − σR σL + σR ≡ (1/2 − s2

eff)2 − s4 eff

(1/2 − s2

eff)2 + s4 eff

An exercise: let’s start from a set of well-measured electroweak (pseudo)-observables s2

eff = 0.23153(16)

mW = 80.385(15) GeV

SLIDE 59

At tree level, all of the observables can be expressed in terms of three parameters

f the SM Lagrangian: or, equivalently, (also )

v, g, g v, e, s ≡ sin θW c ≡ cos θW Γ+− = v 48 √ 2π e3 s3c3 ⇤ −1 2 + 2 s2 ⇥2 + 1 4 ⌅ α = e2 4π , GF = 1 2 √ 2v2 , mZ = e v √ 2sc, mW = e v √ 2s, s2

eff = s2,

e2 = 4πα , v2 = 1 2 √ 2GF , s2 = 1 2 − 1 2

1 − 2

√ 2πα GF m2

Z

Is this consistent with the experimental data? To check, we compute the three Lagrangian parameters in terms of the best-measured observables α, GF , mZ and we plug the resulting values of in the expressions for

v, e, s

mW , s2

eff, Γ⇥+⇥−

Off by many standard deviations!!! mW = 80.939 GeV s2

eff

= 0.21215 Γ⇥+⇥− = 80.842 MeV tree-level predictions experimental values 80.385 ± 0.015 GeV 0.23153 ± 0.00016 83.984 ± 0.086 MeV

SLIDE 60

V V

+

V V ΠV V (q2)

m2

Z

= e2v2 2 s2c2 + ΠZZ(m2

Z)

m2

W

= e2v2 2 s2 + ΠW W (m2

W )

Radiative corrections to the relations between physical observables and Lagrangian params: Obviously the tree level is not good enough! What happened? We tried to use the SM relations at tree level to predict some observables in terms of other observables, and we failed badly GF = 1 2 √ 2v2

1 − ΠW W (0)

m2

W

+ δVB

µ

νµ e ¯ νe

W

+

µ νµ e ¯ νe

ΠWW

+ ...

SLIDE 61

this one is tricky: the hadronic contribution to cannot be computed perturbatively α = e2 4 π

1 + lim

q2−>0

Πγγ(q2) q2 ⇥

+

e− e+ e− e+ e− e+

Πγγ

e− e+ γ

Π

γγ(0)

We can however trade it for another experimental observable: Rhad(q2) = σhad(q2) σ+−(q2) ∆α(mZ) = ∆α⇥(mZ) + ∆αtop(mZ) + ∆α(5)

had(mZ)

                      

calculable α(mZ) = e2 4π

1 + Πγγ(mZ)

mZ ⇥ = α 1 − ∆α(mZ) (This hadronic contribution is one of the biggest sources of uncertainty in EW studies) ∆α(5)

had(mZ) = −m2 Z

3π ∞

4m2

π

Rhad(q2)dq2 q2 (q2 − m2

Z) = 0.02758 ± 0.00035

SLIDE 62

All these corrections can be combined into relations among physical observables, e.g.: m2

W = m2 Z

1

2 + 1 2

1 − 2

√ 2 πα GF m2

Z

(1 + ∆r)

can be parameterized in terms of two

universal corrections and a remainder: ∆r ∆r = ∆α(mZ) − c2 s2 ∆ρ + ∆rrem The leading corrections depend quadratically on but only logarithmically on : mt mH ∆ρ = ΠZZ(0) m2

Z

− ΠW W (0) m2

W

≈ 3 α 16πc2 m2

t

s2m2

Z

+ log m2

H

m2

W

+ . . .

δm2

W

m2

W

≈ c2 c2 − s2 ∆ρ , δ sin2 θeff ≈ − c2 s2 c2 − s2 ∆ ρ In the SM the predictions for and have been fully computed at the two-loop order, plus some leading (top/strong) corrections at three and four loops

mW

sin2 θeff

SLIDE 63

compute radiative corrections

to all of the SM observables

fit the experimental data and

determine the most likely set

f Lagrangian parameters
compute predictions for all the
bservables in terms of the

“best fit” Lagrangian

compare the predictions with

the experimental data and see if they are all consistent (LEP/TEV EWWG, 2012) The radiative corrections bring along a dependence of the experimental

bservables on all the parameters of the SM Lagrangian

It is no longer possible to invert analytically the relations between observables and Lagrangian parameters. But we can still perform a statistical analysis:

Measurement Fit |OmeasOfit|/meas

1 2 3 1 2 3

had(mZ) (5) 0.02750 ± 0.00033 0.02759 mZ [GeV] mZ [GeV] 91.1875 ± 0.0021 91.1874 Z [GeV] Z [GeV] 2.4952 ± 0.0023 2.4959 had [nb] 41.540 ± 0.037 41.478 Rl Rl 20.767 ± 0.025 20.742 Afb A0,l 0.01714 ± 0.00095 0.01645 Al(P) Al(P) 0.1465 ± 0.0032 0.1481 Rb Rb 0.21629 ± 0.00066 0.21579 Rc Rc 0.1721 ± 0.0030 0.1723 Afb A0,b 0.0992 ± 0.0016 0.1038 Afb A0,c 0.0707 ± 0.0035 0.0742 Ab Ab 0.923 ± 0.020 0.935 Ac Ac 0.670 ± 0.027 0.668 Al(SLD) Al(SLD) 0.1513 ± 0.0021 0.1481 sin2eff sin2lept(Qfb) 0.2324 ± 0.0012 0.2314 mW [GeV] mW [GeV] 80.385 ± 0.015 80.377 W [GeV] W [GeV] 2.085 ± 0.042 2.092 mt [GeV] mt [GeV] 173.20 ± 0.90 173.26

March 2012

SLIDE 64

Comparing predictions and experiment (LEP/TEV EWWG 2012)

(the LEP/Tevatron results favor a light Higgs boson) 80.3 80.4 80.5 155 175 195

LHC excluded

mH [GeV] 114 300 600 1000

mt [GeV] mW [GeV]

68% CL

LEP1 and SLD

LEP2 and Tevatron

March 2012

0.231 0.232 0.233 83.6 83.8 84 84.2

68% CL

ll [MeV] sin2

lept eff

mt= 173.2 ± 0.9 GeV mH= 114...1000 GeV

mt mH

March 2012

SLIDE 65

Constraining the SM Higgs mass (LEP/TEV EWWG 2012)

In March 2012, consistency of the SM required mH < 152 GeV at 95% C.L.

1 2 3 4 5 6 100 40 200

mH [GeV] 2

LEP excluded LHC excluded

had = (5)

0.02750±0.00033 0.02749±0.00010

incl. low Q2 data

Theory uncertainty

March 2012

mLimit = 152 GeV

MH [GeV]

March 2012

Z Z had Rl R0 Afb A0,l Al(P) Al(P) Rb R0 Rc R0 Afb A0,b Afb A0,c Ab Ab Ac Ac Al(SLD) Al(SLD) sin2eff sin2lept(Qfb) mW mW W W QW(Cs) QW(Cs) sin2(ee) sin2MS sin2W(N) sin2W(N) gL(N) g2 gR(N) g2

10 10

2

10

3

SLIDE 66

The LHC nails it

SLIDE 67

Sensitivity to individual search channels in the 2011 LHC data

)

2

Higgs boson mass (GeV/c

100 200 300 400 500 600

SM

/
95% CL limit on

1 10

2

10

1

= 4.6-4.7 fb

int

Combined, L = 7 TeV s CMS Preliminary,

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

95% CL expected

SLIDE 68

Sensitivity to individual search channels in the 2011 LHC data

)

2

Higgs boson mass (GeV/c

100 200 300 400 500 600

SM

/
95% CL limit on

1 10

2

10

1

= 4.6-4.7 fb

int

Combined, L = 7 TeV s CMS Preliminary,

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

115 543

95% CL expected

SLIDE 69

Sensitivity to individual search channels in the 2011 LHC data

)

2

Higgs boson mass (GeV/c

100 200 300 400 500 600

SM

/
95% CL limit on

1 10

2

10

1

= 4.6-4.7 fb

int

Combined, L = 7 TeV s CMS Preliminary,

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

)

1

(4.6 fb

2l 2
ZZ
H

115 543 prevailing channel

γ γ WW ZZ

95% CL expected

SLIDE 70

Note how large rates for production and/or decay are not the end of the story: dominant for light Higgs, but swamped by QCD background

)

2

Higgs boson mass (GeV/c

110 115 120 125 130 135 140 145 150 155 160

SM

/
95% CL limit on

1 10

2

10

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H
1

= 4.6-4.7 fb

int

Combined, L = 7 TeV s CMS Preliminary,

Expected limits Combined )

1

bb (4.7 fb

H

)

1

(4.6 fb

H

)

1

(4.7 fb

H

)

1

WW (4.6 fb

H

)

1

4l (4.7 fb

ZZ
H

)

1

2l 2q (4.6 fb

ZZ
H

(VH) (VBF)

Needs leptons in the final state:

q¯ q0 − → V H − → ` `0 b¯ b gg − → H − → b¯ b

95% CL expected

SLIDE 71

The high-resolution channels: two photons and four leptons

H

γ γ

H Z(∗) Z

ℓ− ℓ+ ℓ− ℓ+

Both suppressed!!! (respectively by a loop factor and, for mH < 180 GeV, by the virtuality of the Z ) However, the precise reconstruction of the momenta of the particles in the final state produces a narrow peak around mH in the invariant-mass distribution

SLIDE 72

H → ZZ → 4 H → γγ

(GeV)

l 4

m

80 100 200 300 400

Events / 3 GeV

5 10 15 20 25 30 35

Data =126 GeV

H

m *,ZZ γ Z Z+X

800 600

CMS

1

= 8 TeV, L = 19.7 fb s ;

1

= 7 TeV, L = 5.1 fb s

(GeV)

l 4

m

110 120 130 140 150

Events / 3 GeV

2 4 6 8 10 12 14 16

kin bkg

D > 0.5

[GeV]

γ γ

m

110 120 130 140 150 160 weights - fitted bkg

∑

5

5 10

weights / GeV

∑

20 40 60 80 100 120 140 160 180 Data Signal+background Background Signal = 7 TeV s ,

1

dt = 4.5 fb L

∫

= 8 TeV s ,

1

dt = 20.3 fb L

∫

S/B weighted sum Signal strength categories = 125.4 GeV

H

m

ATLAS

“I think we have it”

[Rolf Heuer at CERN, 04/07/2012]

SLIDE 73

H → ZZ → 4 H → γγ

(GeV)

l 4

m

80 100 200 300 400

Events / 3 GeV

5 10 15 20 25 30 35

Data =126 GeV

H

m *,ZZ γ Z Z+X

800 600

CMS

1

= 8 TeV, L = 19.7 fb s ;

1

= 7 TeV, L = 5.1 fb s

(GeV)

l 4

m

110 120 130 140 150

Events / 3 GeV

2 4 6 8 10 12 14 16

kin bkg

D > 0.5

[GeV]

γ γ

m

110 120 130 140 150 160 weights - fitted bkg

∑

5

5 10

weights / GeV

∑

20 40 60 80 100 120 140 160 180 Data Signal+background Background Signal = 7 TeV s ,

1

dt = 4.5 fb L

∫

= 8 TeV s ,

1

dt = 20.3 fb L

∫

S/B weighted sum Signal strength categories = 125.4 GeV

H

m

ATLAS

Z γ∗ ℓ ℓ ℓ ℓ

“I think we have it”

[Rolf Heuer at CERN, 04/07/2012]

SLIDE 74

H → ZZ → 4 H → γγ

(GeV)

l 4

m

80 100 200 300 400

Events / 3 GeV

5 10 15 20 25 30 35

Data =126 GeV

H

m *,ZZ γ Z Z+X

800 600

CMS

1

= 8 TeV, L = 19.7 fb s ;

1

= 7 TeV, L = 5.1 fb s

(GeV)

l 4

m

110 120 130 140 150

Events / 3 GeV

2 4 6 8 10 12 14 16

kin bkg

D > 0.5

[GeV]

γ γ

m

110 120 130 140 150 160 weights - fitted bkg

∑

5

5 10

weights / GeV

∑

20 40 60 80 100 120 140 160 180 Data Signal+background Background Signal = 7 TeV s ,

1

dt = 4.5 fb L

∫

= 8 TeV s ,

1

dt = 20.3 fb L

∫

S/B weighted sum Signal strength categories = 125.4 GeV

H

m

ATLAS

“I think we have it”

[Rolf Heuer at CERN, 04/07/2012]

SLIDE 75

mH = 125.0 ± 0.27 ± 0.15 GeV

[CMS, 1412.8662] [GeV]

H

m 123 123.5 124 124.5 125 125.5 126 126.5 127 127.5 Λ

2ln

1 2 3 4 5 6 7

σ 1 σ 2

ATLAS

1

Ldt = 4.5 fb

∫

= 7 TeV s

1

Ldt = 20.3 fb

∫

= 8 TeV s

l +4 γ γ Combined γ γ → H l 4 → ZZ* → H without systematics

mH = 125.4 ± 0.4 ± 0.2 GeV

[ATLAS, 1406.3827]

Determination of the Higgs mass by ATLAS and CMS

(GeV)

H

m

123 124 125 126 127

ln L

2

1 2 3 4 5 6 7 8 9 10

tagged

H

ZZ tagged

H

Combined:

stat. + syst.
stat. only

CMS

(7 TeV)

1

(8 TeV) + 5.1 fb

1

19.7 fb

ZZ

+ H
H

(ggH,ttH),

µ

,

ZZ

µ (VBF,VH)

µ

(syst)

0.15

+0.14

(stat)

0.27

+0.26

= 125.02

H

m

SLIDE 76

Profile of a 125-GeV Higgs boson at the LHC with 8 TeV

BR(H → b¯ b) = 57.7% , BR(H → WW ∗) = 21.5% , BR(H → ZZ∗) = 2.6% , BR(H → τ +τ −) = 6.3% , BR(H → gg) = 8.6% , BR(H → γγ) = 0.23%

(relative errors on the BRs range from 3% for bb to 10% for gg ) Theory predictions from the LHC Higgs cross-section Working Group, arXiv:1307.1347

σ(pp → H) = 19.3 +7%+8%

−8%−7% pb ,

σ(pp → jjH) = 1.6 +0.2%+2.6%

−0.2%−2.4% pb

σ(pp → ttH) = 0.13 +3.8%+8.1%

−9.3%−8.1% pb

σ(pp → WH) = 0.70 +1%+2.3%

−1%−2.3% pb ,

σ(pp → ZH) = 0.42 +3.1%+2.5%

−3.1%−2.5% pb

SLIDE 77

125 GeV is a lucky mass, several decays accessible

SM

/
Best fit

0.5 1 1.5 2

0.44 ± = 0.84 µ

bb tagged

H

0.28 ± = 0.91 µ

tagged

H

0.21 ± = 0.83 µ

WW tagged

H

0.29 ± = 1.00 µ

ZZ tagged

H

0.24 ± = 1.12 µ

tagged

H

0.14 ± = 1.00 µ

Combined

CMS

(7 TeV)

1

(8 TeV) + 5.1 fb

1

19.7 fb

= 125 GeV

H

m

= 0.96

SM

p

) µ Signal strength (

0.5 1 1.5 2

ATLAS Prelim.

1

Ldt = 4.5-4.7 fb

∫

= 7 TeV s

1

Ldt = 20.3 fb

∫

= 8 TeV s

= 125.36 GeV

H

m

Phys. Rev. D 90, 112015 (2014)

0.27

0.27

+

= 1.17 µ γ γ → H

0.11

0.16

+ 0.23

0.23

+

arXiv:1408.5191

0.33

0.40

+

= 1.44 µ 4l → ZZ* → H

0.11

0.21

+ 0.31

0.34

+

arXiv:1412.2641

0.21

0.23

+

= 1.09 µ ν l ν l → WW* → H

0.14

0.17

+ 0.15

0.16

+

arXiv:1409.6212

0.4

0.4

+

= 0.5 µ b b → W,Z H

0.2

0.2

+ 0.3

0.3

+

0.4

0.4

+

= 1.4 µ τ τ → H

0.3

0.3

+ 0.3

0.3

+

ATLAS-CONF-2014-061

Total uncertainty µ

n

σ 1 ±

(stat.) σ

)

theory sys inc.

(

σ

released 12.01.2015

SLIDE 78

The Higgs couplings to the other SM particles are proportional to their masses:

Particle mass (GeV)

0.1 1 10 100

1/2

/2v)

V

r (g

f

λ

4

10

3

10

2

10

1

10 1 WZ t b τ µ

) fit ε (M, 68% CL 95% CL 68% CL 95% CL SM Higgs 68% CL 95% CL SM Higgs

CMS

(7 TeV)

1

(8 TeV) + 5.1 fb

1

19.7 fb

SLIDE 79

The angular distribution of the decay products allows to test spin and parity:

(spin 2 disfavored) (pseudoscalar disfavored) )

+

/ L

P

J

ln(L ×

2
30
20
10

10 20 30 40

Pseudoexperiments

0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

γ γ ZZ + WW + → )

m +

X(2 → gg

CMSPreliminary

(7 TeV)

1

(8 TeV) + 5.1 fb

1

19.7 fb

Observed

+ m +

2

SLIDE 80

The ultimate test of the Higgs mechanism: self-couplings

V = 1 2(2λv2)H2 + λvH3 + 1 4λH4

The Higgs potential includes trilinear and quartic self-couplings: The three-Higgs coupling can be extracted from Higgs pair production. However, suppressed by phase space and diluted by other topologies. E.g., The coupling could be measured with ~50% accuracy in a high-luminosity LHC run and with 10%-20% accuracy at the ILC with 1 TeV No hope to measure directly the four-Higgs coupling via three-Higgs production

g g H H t g g H∗ H H t

SLIDE 81

Status of the EW fit after the Higgs discovery (Gfitter collaboration, 2014)

)

eff l

(

2

sin

0.2308 0.231 0.2312 0.2314 0.2316 0.2318 0.232 0.2322

[GeV]

W

M

80.32 80.34 80.36 80.38 80.4 80.42 80.44 80.46 80.48 80.5

68% and 95% CL contours ) measurements

eff f

(

2

and sin

W

direct M ) and Z widths measurements

eff f

(

2

, sin

W

fit w/o M measurements

H

) and M

eff f

(

2

, sin

W

fit w/o M and Z widths measurements

H

), M

eff f

(

2

, sin

W

fit w/o M

1

± world comb.

W

M

1

± ) LEP+SLC

eff f

(

2

sin

G fitter SM

Jul ’14

SLIDE 82

Status of the EW fit after the Higgs discovery (Gfitter collaboration, 2014)

)

eff l

(

2

sin

0.231 0.2311 0.2312 0.2313 0.2314 0.2315 0.2316 0.2317 0.2318 0.2319

[GeV]

W

M

80.32 80.34 80.36 80.38 80.4 80.42 80.44 80.46

68% and 95% CL fit contour ) measurements

eff f

(

2

and sin

W

w/o M Present SM fit Prospect for LHC Prospect for ILC/GigaZ Present measurement ILC precision LHC precision

1

±

W

M

1

± )

eff f

(

2

sin

G fitter SM

Jul ’14

(300 fb-1)

SLIDE 83

The fate of the SM: stability of the electroweak vacuum

SLIDE 84

The fate of the SM: stability of the electroweak vacuum

φ V (φ) v V0(φ) = m2 |φ|2 + λ |φ|4 , v = r −m2 λ Tree-level scalar potential:

SLIDE 85

The fate of the SM: stability of the electroweak vacuum

φ V (φ) v V0(φ) = m2 |φ|2 + λ |φ|4 , v = r −m2 λ Tree-level scalar potential: V (φ) = m2(µ) |φ(µ)|2 + λ(µ) |φ(µ)|4 + ∆V loop Including quantum corrections:

SLIDE 86

The fate of the SM: stability of the electroweak vacuum

φ V (φ) v V0(φ) = m2 |φ|2 + λ |φ|4 , v = r −m2 λ Tree-level scalar potential: V (φ) = m2(µ) |φ(µ)|2 + λ(µ) |φ(µ)|4 + ∆V loop Including quantum corrections: At large , the potential is dominated by the quartic term:

φ

V (φ ⇥ v) λ(µ φ) |φ|4

SLIDE 87

The fate of the SM: stability of the electroweak vacuum

φ V (φ) v V0(φ) = m2 |φ|2 + λ |φ|4 , v = r −m2 λ Tree-level scalar potential: V (φ) = m2(µ) |φ(µ)|2 + λ(µ) |φ(µ)|4 + ∆V loop Including quantum corrections: At large , the potential is dominated by the quartic term:

φ

V (φ ⇥ v) λ(µ φ) |φ|4 If the quartic coupling turns negative at some large scale, the potential is unstable

SLIDE 88

The fate of the SM: stability of the electroweak vacuum

φ V (φ) v V0(φ) = m2 |φ|2 + λ |φ|4 , v = r −m2 λ Tree-level scalar potential: V (φ) = m2(µ) |φ(µ)|2 + λ(µ) |φ(µ)|4 + ∆V loop Including quantum corrections: At large , the potential is dominated by the quartic term:

φ

V (φ ⇥ v) λ(µ φ) |φ|4 If the quartic coupling turns negative at some large scale, the potential is unstable The Higgs field can tunnel to a much larger value, destroying the EW vacuum

SLIDE 89

The fate of the SM: stability of the electroweak vacuum

φ V (φ) v V0(φ) = m2 |φ|2 + λ |φ|4 , v = r −m2 λ Tree-level scalar potential: V (φ) = m2(µ) |φ(µ)|2 + λ(µ) |φ(µ)|4 + ∆V loop Including quantum corrections: At large , the potential is dominated by the quartic term:

φ

V (φ ⇥ v) λ(µ φ) |φ|4 If the quartic coupling turns negative at some large scale, the potential is unstable The lifetime of the EW vacuum must be longer than the age of the Universe (metastability) The Higgs field can tunnel to a much larger value, destroying the EW vacuum

SLIDE 90

We can extract the weak-scale value of from .+ higher orders

λ m2

H = 2λv2

dλ d log µ = 1 16π2 ⇢ 24 λ2 + λ ⇥ 12 Y 2

t + 12 Y 2 b + 4 Y 2 τ − 9 g2 − 3g0 2⇤

+9 8 g4 + 3 8g0 4 + 3 4 g2 g0 2 − 6 Y 4

t − 6 Y 4 b − 2 Y 4 τ

+ higher orders

is the scale at which new physics must rescue the SM (anyway, )

Λ ≤ ΛPlanck Λ

λ λ Y 2 λ2 λ g2 g4 Y 4

Large mH : prevails, grows with µ until it blows up at some scale (Landau pole)

λ2 Λ λ

Small mH : prevails, decreases with µ until it turns negative at (vacuum instability)

Λ λ

−Y 4

t

Loops of SM particles determine the dependence of on the renormalization scale µ

λ

SLIDE 91

102 104 106 108 1010 1012 1014 1016 1018 1020

0.04
0.02

0.00 0.02 0.04 0.06 0.08 0.10 RGE scale m in GeV Higgs quartic coupling l 3s bands in Mt = 173.3 ± 0.8 GeV HgrayL a3HMZL = 0.1184 ± 0.0007HredL Mh = 125.1 ± 0.2 GeV HblueL Mt = 171.1 GeV asHMZL = 0.1163 asHMZL = 0.1205 Mt = 175.6 GeV

107 108 109 1010 1011 1012 1013 1014 1016 120 122 124 126 128 130 132 168 170 172 174 176 178 180 Higgs pole mass Mh in GeV Top pole mass Mt in GeV 1017 1018 1019 1,2,3 s Instability Stability Meta-stability

IF the SM is valid up to the Planck scale, the vacuum is most likely metastable

Plots from 1307.3536v4

mH ≈ 125 GeV is right at the edge between the stability and metastability regions

SLIDE 92

102 104 106 108 1010 1012 1014 1016 1018 1020

0.04
0.02

0.00 0.02 0.04 0.06 0.08 0.10 RGE scale m in GeV Higgs quartic coupling l 3s bands in Mt = 173.3 ± 0.8 GeV HgrayL a3HMZL = 0.1184 ± 0.0007HredL Mh = 125.1 ± 0.2 GeV HblueL Mt = 171.1 GeV asHMZL = 0.1163 asHMZL = 0.1205 Mt = 175.6 GeV

107 108 109 1010 1011 1012 1013 1014 1016 120 122 124 126 128 130 132 168 170 172 174 176 178 180 Higgs pole mass Mh in GeV Top pole mass Mt in GeV 1017 1018 1019 1,2,3 s Instability Stability Meta-stability

IF the SM is valid up to the Planck scale, the vacuum is most likely metastable But should we really buy that “IF”?

Plots from 1307.3536v4

mH ≈ 125 GeV is right at the edge between the stability and metastability regions

SLIDE 93

III) Beyond the Standard Model

SLIDE 94

The Standard Model does an excellent job in describing physics at the weak scale. Still, it is unlikely that it is valid all the way up to the scale of quantum gravity

The SM does not account for neutrino oscillations (this, however, can easily be

fixed by adding heavy and sterile right-handed neutrinos to the theory)

The SM does not include a suitable candidate for Dark Matter, and cannot justify

the matter-antimatter asymmetry in the Universe Observational arguments for BSM physics

The SM has many (>20) arbitrary parameters, and a rather complicated structure

(“odd” gauge group, generation mixing, large mass hierarchies among fermions). It would be nice to embed it in a simpler and more predictive theory (e.g., a GUT).

Quantum corrections destabilize the Higgs mass inducing a quadratic dependence
n the cutoff scale that regularizes the loop integrals (the hierarchy problem)

Theoretical arguments for BSM physics

SLIDE 95

The hierarchy problem of the Standard Model

The SM fermion masses are protected by chiral symmetry:

mf × fL fR × fL fR + + · · ·

, thus if is small it stays so even after including quantum corrections

mf δmf ∝ mf

There is no analogous mechanism to protect the scalar mass term:

×

H H H H H

fL fR m2

H

+ + · · ·

λf λf H H H S λS

+ · · ·

The radiative corrections depend quadratically on the cutoff scale where New Physics kicks in: If the validity of the SM extends up to the Planck scale (or the GUT scale) we need an extremely fine-tuned cancellation between the tree-level mass and the radiative corrections

∆m2

H ⊃ 3 GF Λ2

4 √ 2π2

2 m2

W + m2 Z + m2 H − 4 m2 t

SLIDE 96

New physics intervenes at the TeV scale (supersymmetry, composite Higgs models, ...)
The scale of quantum gravity is itself at the TeV (models with large extra dimensions)
Tough luck, live with fine tuning (SM up to high scales: “nightmare” scenario for LHC?)

Different approaches are possible:

SLIDE 97

Supersymmetry and the MSSM

×

H H H H H

fL fR m2

H

+ + · · ·

λf λf H H H S λS

Fermions and bosons enter the quantum corrections to the Higgs mass with opposite sign In a supersymmetric theory, each fermion has a bosonic partner with the same mass and internal quantum numbers (their couplings to the Higgs are related, ). Their quadratically divergent contributions to the Higgs mass cancel each other λS = λ2

f

In the Minimal Supersymmetric Standard Model (MSSM) every SM particle is promoted to a supermultiplet (however, two Higgs supermultiplets are required) The superpartners must be heavier than the ordinary SM particles SUSY must be broken by explicit mass terms for the new particles These SUSY-breaking masses MS are soft, i.e. they do not reintroduce quadratic divergences:

∆m2

H ∝

λ2 16π2 M 2

S

SLIDE 98

Supersymmetry and the MSSM

×

H H H H H

fL fR m2

H

+ + · · ·

λf λf H H H S λS

Fermions and bosons enter the quantum corrections to the Higgs mass with opposite sign

1

In a supersymmetric theory, each fermion has a bosonic partner with the same mass and internal quantum numbers (their couplings to the Higgs are related, ). Their quadratically divergent contributions to the Higgs mass cancel each other λS = λ2

f

In the Minimal Supersymmetric Standard Model (MSSM) every SM particle is promoted to a supermultiplet (however, two Higgs supermultiplets are required) The superpartners must be heavier than the ordinary SM particles SUSY must be broken by explicit mass terms for the new particles These SUSY-breaking masses MS are soft, i.e. they do not reintroduce quadratic divergences:

∆m2

H ∝

λ2 16π2 M 2

S

SLIDE 99

Composite Higgs models

The hierarchy problem originates from the fact that the SM Higgs is an elementary scalar (therefore its mass cannot be protected by chiral or gauge symmetries) An intermediate approach is possible: There is a light Higgs scalar (to satisfy the electroweak precision observables) but it is composite, the light remnant of a new strong dynamics responsible for EWSB The classical alternative to the SM Higgs mechanism, i.e. dynamical symmetry breaking such as in Technicolor models, is disfavoured by flavour and electroweak precision tests To preserve EW observables, the particles of the strong sector should be above the TeV scale The composite Higgs can be lighter than the rest if it is a pseudo-Goldstone boson

f a global symmetry of the strong sector (e.g. Little Higgs, Holographic Higgs, ...)

Even if the new states are heavy, the composite nature of the Higgs should appear at the LHC:

high-energy growth of the V V V V cross sections
modified couplings of the Higgs to SM particles

SLIDE 100

Models with Large Extra Dimensions

Supersymmetry helps the Higgs boson cross the “desert” between MEW and MPlanck An alternative paradigm: there is no desert, and MPlanck ~ MEW !!! The simplest scenario: Arkani-Hamed et al., hep-ph/9803315

4-d spacetime extra compactified dimensions yi yj n dimensions compactified

ver a radius R

R the usual 4-d spacetime

SM fields The SM fields live on a 4-d “brane” but gravity propagates in the “bulk” The “true” scale of quantum gravity can be lower than the apparent 4-dim Planck scale:

M 2

Pl = M n+2 ∗

(2πR)n n = 1, M∗ = 10 TeV − → R ≈ 1010 m n = 2, M∗ = 10 TeV − → R ≈ 0.1 mm

Gravity is untested below 0.1 mm. For n = 2 the scale of quantum gravity could be as low as 10 TeV (and even lower for larger n !!!)

SLIDE 101

From a 4d perspective, fields that live in the (4+n)d bulk look like a tower of “Kaluza-Klein” states E.g., a massless scalar living in 5 dimensions can be Fourier-decomposed along the compact dimension:

Φ(xµ, Z) = Φ(xµ, Z + 2πR) Φ(xµ, Z) =

k=0,±1 ...

φk(xµ) eikZ/R 5 Φ(xµ, Z) = 0 − →

4 + k2

R2

φk(xµ) = 0

The zero mode remains massless, the other modes have increasing masses mk = |k|

R

A typical signature of extra-dim models is the production of gravitons that escape in the bulk Each KK graviton couples to SM matter like 1/MPl , but the sum over the whole tower goes like .

1/M∗

The collider signature is a photon (or a jet) plus missing energy Depending on the specific model, other particles may live in the bulk and have KK excitations

SLIDE 102

After the first two-year run of the LHC with c.o.m. energy of 7-8 TeV, all we got from BSM searches is bounds on the new-particle masses

SLIDE 103

Mass scales [GeV] 200 400 600 800 1000 1200 1400 1600 1800

233

' λ µ tbt →

R

t ~

233

λ t ν τ µ →

R

t ~

123

λ t ν τ µ →

R

t ~

122

λ t ν e µ →

R

t ~

112

'' λ qqqq →

R

q ~

233

' λ µ qbt → q ~

231

' λ µ qbt → q ~

233

λ ν qll → q ~

123

λ ν qll → q ~

122

λ ν qll → q ~

112

'' λ qqqq → g ~

323

'' λ tbs → g ~

112

'' λ qqq → g ~

113/223

'' λ qqb → g ~

233

' λ µ qbt → g ~

231

' λ µ qbt → g ~

233

λ ν qll → g ~

123

λ ν qll → g ~

122

λ ν qll → g ~ χ ∼ l → l ~ χ ∼ χ ∼ ν τ τ τ →

±

χ ∼

2

χ ∼ χ ∼ χ ∼ ν τ ll →

±

χ ∼

2

χ ∼ χ ∼ χ ∼ H W →

2

χ ∼

±

χ ∼ χ ∼ χ ∼ H Z →

2

χ ∼

2

χ ∼ χ ∼ χ ∼ W Z →

2

χ ∼

±

χ ∼ χ ∼ χ ∼ Z Z →

2

χ ∼

2

χ ∼ χ ∼ χ ∼ ν ν

l

+

l →

χ

∼

+

χ ∼ χ ∼ χ ∼ ν lll →

±

χ ∼

2

χ ∼ χ ∼ bZ → b ~ χ ∼ tW → b ~ χ ∼ b → b ~ ) H

1

χ ∼ t →

1

t ~ ( →

2

t ~ ) Z

1

χ ∼ t →

1

t ~ ( →

2

t ~ H G) → χ ∼ ( χ ∼ t b → t ~ ) χ ∼ W →

+

χ ∼ b( → t ~ χ ∼ t → t ~ χ ∼ q → q ~ )) χ ∼ W →

±

χ ∼ t( → b ~ b( → g ~ ) χ ∼ W →

±

χ ∼ qq( → g ~ ) χ ∼ t → t ~ t( → g ~ χ ∼ tt → g ~ χ ∼ bb → g ~ χ ∼ qq → g ~

SUS-13-006 L=19.5 /fb SUS-13-008 SUS-13-013 L=19.5 /fb SUS-13-011 L=19.5 /fb

x = 0.25 x = 0.50 x = 0.75

SUS-14-002 L=19.5 /fb SUS-13-006 L=19.5 /fb

x = 0.05 x = 0.50 x = 0.95

SUS-13-006 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-13-007 SUS-13-013 L=19.4 19.5 /fb SUS-12-027 L=9.2 /fb SUS 13-019 L=19.5 /fb SUS-14-002 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-13-003 L=19.5 9.2 /fb SUS-13-006 L=19.5 /fb SUS-12-027 L=9.2 /fb EXO-12-049 L=19.5 /fb SUS-14-011 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-13-008 L=19.5 /fb SUS-12-027 L=9.2 /fb EXO-12-049 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-12-027 L=9.2 /fb SUS-13-024 SUS-13-004 L=19.5 /fb SUS-13-003 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-13-019 L=19.5 /fb SUS-13-018 L=19.4 /fb SUS-13-014 L=19.5 /fb SUS-14-011 SUS-13-019 L=19.3 19.5 /fb SUS-13-008 SUS-13-013 L=19.5 /fb SUS-13-024 SUS-13-004 L=19.5 /fb SUS-13-013 L=19.5 /fb

x = 0.20 x = 0.50

SUS-12-027 L=9.2 /fb SUS-13-003 L=19.5 9.2 /fb SUS-12-027 L=9.2 /fb SUS-13-008 SUS-13-013 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-14-002 L=19.5 /fb SUS-12-027 L=9.2 /fb SUS-13-013 L=19.5 /fb SUS-13-006 L=19.5 /fb

x = 0.05 x = 0.50 x = 0.95

SUS-13-006 L=19.5 /fb

RPV gluino production squark stop sbottom EWK gauginos slepton

Summary of CMS SUSY Results* in SMS framework

CMS Preliminary

m(mother)-m(LSP)=200 GeV m(LSP)=0 GeV

ICHEP 2014

lsp

m ⋅ +(1-x)

mother

m ⋅ = x

intermediate

m For decays with intermediate mass, Only a selection of available mass limits *Observed limits, theory uncertainties not included Probe *up to* the quoted mass limit

SLIDE 104

Model

ℓ, γ

Jets

Emiss

T

L dt[fb−1]

Mass limit Reference

Extra dimensions Gauge bosons CI DM LQ Heavy quarks Excited fermions Other

ADD GKK + g/q − 1-2 j Yes 4.7

n = 2 1210.4491

4.37 TeV

MD

ADD non-resonant ℓℓ 2e, µ − − 20.3

n = 3 HLZ ATLAS-CONF-2014-030

5.2 TeV

MS

ADD QBH → ℓq 1 e, µ 1 j − 20.3

n = 6 1311.2006

5.2 TeV

Mth

ADD QBH − 2 j − 20.3

n = 6 to be submitted to PRD

5.82 TeV

Mth

ADD BH high Ntrk 2 µ (SS) − − 20.3

n = 6, MD = 1.5 TeV, non-rot BH 1308.4075

5.7 TeV

Mth

ADD BH high pT ≥ 1 e, µ ≥ 2 j − 20.3

n = 6, MD = 1.5 TeV, non-rot BH 1405.4254

6.2 TeV

Mth

RS1 GKK → ℓℓ 2 e, µ − − 20.3

k/MPl = 0.1 1405.4123

2.68 TeV

GKK mass

RS1 GKK → WW → ℓνℓν 2 e, µ − Yes 4.7

k/MPl = 0.1 1208.2880

1.23 TeV

GKK mass

Bulk RS GKK → ZZ → ℓℓqq 2 e, µ 2 j / 1 J − 20.3

k/MPl = 1.0 ATLAS-CONF-2014-039

730 GeV

GKK mass

Bulk RS GKK → HH → b¯ bb¯ b − 4 b − 19.5

k/MPl = 1.0 ATLAS-CONF-2014-005

590-710 GeV

GKK mass

Bulk RS gKK → tt 1 e, µ ≥ 1 b, ≥ 1J/2j Yes 14.3

BR = 0.925 ATLAS-CONF-2013-052

2.0 TeV

gKK mass

S1/Z2 ED 2 e, µ − − 5.0

1209.2535

4.71 TeV

MKK ≈ R−1

UED 2 γ − Yes 4.8

ATLAS-CONF-2012-072

1.41 TeV

Compact. scale R−1

SSM Z ′ → ℓℓ 2 e, µ − − 20.3

1405.4123

2.9 TeV

Z′ mass

SSM Z ′ → ττ 2 τ − − 19.5

ATLAS-CONF-2013-066

1.9 TeV

Z′ mass

SSM W ′ → ℓν 1 e, µ − Yes 20.3

ATLAS-CONF-2014-017

3.28 TeV

W′ mass

EGM W ′ → WZ → ℓν ℓ′ℓ′ 3 e, µ − Yes 20.3

1406.4456

1.52 TeV

W′ mass

EGM W ′ → WZ → qqℓℓ 2 e, µ 2 j / 1 J − 20.3

ATLAS-CONF-2014-039

1.59 TeV

W′ mass

LRSM W ′

R → tb

1 e, µ 2 b, 0-1 j Yes 14.3

ATLAS-CONF-2013-050

1.84 TeV

W′ mass

LRSM W ′

R → tb

0 e, µ ≥ 1 b, 1 J − 20.3

to be submitted to EPJC

1.77 TeV

W′ mass

CI qqqq − 2 j − 4.8

η = +1 1210.1718

7.6 TeV

Λ

CI qqℓℓ 2 e, µ − − 20.3

ηLL = −1 ATLAS-CONF-2014-030

21.6 TeV

Λ

CI uutt 2 e, µ (SS) ≥ 1 b, ≥ 1 j Yes 14.3

|C| = 1 ATLAS-CONF-2013-051

3.3 TeV

Λ

EFT D5 operator (Dirac) 0 e, µ 1-2 j Yes 10.5

at 90% CL for m(χ) < 80 GeV ATLAS-CONF-2012-147

731 GeV

M∗

EFT D9 operator (Dirac) 0 e, µ 1 J, ≤ 1 j Yes 20.3

at 90% CL for m(χ) < 100 GeV 1309.4017

2.4 TeV

M∗

Scalar LQ 1st gen 2 e ≥ 2 j − 1.0

β = 1 1112.4828

660 GeV

LQ mass

Scalar LQ 2nd gen 2 µ ≥ 2 j − 1.0

β = 1 1203.3172

685 GeV

LQ mass

Scalar LQ 3rd gen 1 e, µ, 1 τ 1 b, 1 j − 4.7

β = 1 1303.0526

534 GeV

LQ mass

Vector-like quark TT → Ht + X 1 e, µ ≥ 2 b, ≥ 4 j Yes 14.3

T in (T,B) doublet ATLAS-CONF-2013-018

790 GeV

T mass

Vector-like quark TT → Wb + X 1 e, µ ≥ 1 b, ≥ 3 j Yes 14.3

isospin singlet ATLAS-CONF-2013-060

670 GeV

T mass

Vector-like quark TT → Zt + X 2/≥3 e, µ ≥2/≥1 b − 20.3

T in (T,B) doublet ATLAS-CONF-2014-036

735 GeV

T mass

Vector-like quark BB → Zb + X 2/≥3 e, µ ≥2/≥1 b − 20.3

B in (B,Y) doublet ATLAS-CONF-2014-036

755 GeV

B mass

Vector-like quark BB → Wt + X 2 e, µ (SS) ≥ 1 b, ≥ 1 j Yes 14.3

B in (T,B) doublet ATLAS-CONF-2013-051

720 GeV

B mass

Excited quark q∗ → qγ 1 γ 1 j − 20.3

nly u∗ and d∗, Λ = m(q∗)

1309.3230

3.5 TeV

q∗ mass

Excited quark q∗ → qg − 2 j − 20.3

nly u∗ and d∗, Λ = m(q∗)

to be submitted to PRD

4.09 TeV

q∗ mass

Excited quark b∗ → Wt 1 or 2 e, µ 1 b, 2 j or 1 j Yes 4.7

left-handed coupling 1301.1583

870 GeV

b∗ mass

Excited lepton ℓ∗ → ℓγ 2 e, µ, 1 γ − − 13.0

Λ = 2.2 TeV 1308.1364

2.2 TeV

ℓ∗ mass

LSTC aT → W γ 1 e, µ, 1 γ − Yes 20.3

to be submitted to PLB

960 GeV

aT mass

LRSM Majorana ν 2 e, µ 2 j − 2.1

m(WR) = 2 TeV, no mixing 1203.5420

1.5 TeV

N0 mass

Type III Seesaw 2 e, µ − − 5.8

|Ve|=0.055, |Vµ|=0.063, |Vτ|=0 ATLAS-CONF-2013-019

245 GeV

N± mass

Higgs triplet H±± → ℓℓ 2 e, µ (SS) − − 4.7

DY production, BR(H ±± → ℓℓ)=1 1210.5070

409 GeV

H±± mass

Multi-charged particles − − − 4.4

DY production, |q| = 4e 1301.5272

490 GeV

multi-charged particle mass

Magnetic monopoles − − − 2.0

DY production, |g| = 1gD 1207.6411

862 GeV

monopole mass

Mass scale [TeV] 10−1 1 10

√s = 7 TeV √s = 8 TeV

ATLAS Exotics Searches* - 95% CL Exclusion

Status: ICHEP 2014

ATLAS Preliminary

L dt = (1.0 - 20.3) fb−1

√s = 7, 8 TeV

*Only a selection of the available mass limits on new states or phenomena is shown.

SLIDE 105

After a two-year shutdown, the LHC is about to restart at 13-14 TeV. Let’s hope for new exciting discoveries...

SLIDE 106