MF, August 2004 flhiggs 1

A heavy Higgs boson from flavor and electroweak symmetry unification

A heavy Higgs boson from flavor and electroweak symmetry unification

Boston, August 2004Boston, August 2004

Little Higgs meets little flavon

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Waiting for the LHCWaiting for the LHC

• Can we guess the mass of the Higgs?

• Is it light (< 200 GeV) or heavy (> 200 GeV)?

• Precision measurements (and SUSY) say it is

light

• Is there any prediction for a heavy mass?

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What is natural (and stable)What is natural (and stable)

• Dirac: dimensionless parameters should be of order one

•‘t Hooft: dimensionful parameters should be of the order

of the largest scale in the problem, unless a symmetry

arises in the limit of the coupling going to zero

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The little hierarchy problemThe little hierarchy problem

• Naturalness in the SM seems to demand new

physics at or around 1 TeV

• Precision measurements do not show any

departure from standard physics up to 10 TeV

How to use this little hierarchy problem to guess new physics?

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Higgs as a pseudo-Goldstone bosonHiggs as a pseudo-Goldstone boson

SU(3) SU(2)

€

→

Problem: Goldstone bosons are exactly massless

Explicit breaking of SU(3) to make them into pseudo

€

L = L0 + ε1L1

€

ε1But is not small in the SM:

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The little-Higgs mechanism: an example [Schmaltz, hep-ph/0210415]

The little-Higgs mechanism: an example [Schmaltz, hep-ph/0210415]

€

L = L0 + ε1L1 + ε2L2

collective symmetry breaking:

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Bringing flavor into the gameBringing flavor into the game

• Horizontal flavor symmetry

• Heavy scalar fields, the flavons

• Spontaneous breaking

• Hierarchy in VEV’s explains that in mass

matrices

• Stability (usually problematic to keep v/f<1)

Froggart-Nielsen mechanism

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RequestsRequests

• Unified electroweak and flavor symmetry• Dynamically generated potential with the desired vacuum• Stable scales, i.e., only small radiative corrections (no fine

tuning)• Appropriate textures (from charges and vev)

a little-Higgs inspired scenario

Little Higgs meets little flavon: the flhiggs model

[F. Bazzocchi and MF, hep-ph/0407358]

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Group structureGroup structure

SU(10) [SU(3)xU(1)]WxU(1)X xU(1)F

SO(10)

spontaneous

explicit2 2

2

[SU(3)xU(1)]WxU(1)X xU(1)F

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The sigma modelThe sigma model

vacuum

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The sigma model, IIThe sigma model, II

Lagrangian

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Effective potentialEffective potential

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Example: the right-handed neutrinosExample: the right-handed neutrinos

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Parameters in the potentialParameters in the potential

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flhiggs: 2 triplets of opposite flavor charge, 2 triplets of opposite X charge

this VEV breaksSU(3)xU(1)xU(1)to U(1)Q

Low-energy effective theoryLow-energy effective theory

[SU(3)xU(1)]WxU(1)X xU(1)F

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Experimental constrainsExperimental constrains

• Tree-level deviations in ballpark of radiative corrrections

• T parameter and Weinberg angle (at the 10-2 level)

• Z’ mass > 690 GeV

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Particle spectrum Particle spectrum

• vW fixed by GF

• vF fixed by experimental constrains• f fixed by texture parameter

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TexturesTextures

quarks

leptons

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The numerical analysisThe numerical analysis

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The (lightest) Higgs bosonThe (lightest) Higgs boson

• Gaussian distribution for all parameters of potential around 1 with spread of 20%