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Neutrinos and unification from a minimal gauge extension

Sofiane Boucenna LNF-INFN

!"Neutrinos from GUTs down to low energies", Garching 26/11/2015.

Neutrinos from GUTs down to low energies

low energies up to GUTs

Neutrinos are everywhere...

Neutrino masses are a great window onto high scales/NP

COSMO ASTRO BAU

DM FLAVORGUT

... and not only because of the Higgs discovery!!!

2012 was a landmark year...

Daya-Bay observed the e lec t ron-ant ineut r ino disappearance, giving a precise measurement of the last unknown neutrino mixing angle; the reactor angle.!

Mixing angles seem "anarchical" now ...

There are many, many ways to generate neutrino masses... but we can distinguish two main classes of models:!!High scale models!!!Low scale models!

nu Masses

Krauss-Nasri-Trodden, 03'

Cheng-Li, 80'!Zee, 86'!Babu, 88'

Ma, 98', 06'Zee, 80'

[Review: !The Low-scale approach to neutrino masses,!B-Morisi-Valle, 14']

The low scale approach

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Neutrino mass from gauge loop?

Expected features:➢ More predictability➢ Rich pheno; LHC

1. Radiative nu masses via W!2. Unification without GUT!3. Flavor without flavor symmetry

Outline

based on:!B-Morisi-Valle, PRD'14!B-Fonseca-GonzalesCanales-Valle, PRD(R)'15!B-Vicente-Valle, PRD'15

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1/3 Gauge origin of nu mass

Z'

We are then led to

;

The electric and lepton charges are given as:! ,

➢ Explain why we have three families; anomaly cancellation implies #families=#colors

➢ One quark family is treated differently. If third gen, origin of large top mass?

➢ Tree-level Z'-mediated FCNC (L-quarks)➢ Rich LHC pheno; Z', W', extra quarks, etc.➢ Many variants; applies to different pheno needs➢ ...➢ Minimal embedding of the SM EW group

[Singer-Valle-Schechter, 80'!Singer-Valle, 83'!Pisano-Pleitez, 92'!Frampton, 92', ...]!!

3-3-1 gauge extensions pros:

Fermions & scalars content

(3*, -1/3) (1, 0)

(3*, -1/3) (3*, -1/3)(3*, 2/3)

(3*, 1/3)(3, 0)(3, 0)

Fermions & scalars content

(3*, -1/3) (1, 0)

(3*, -1/3) (3*, -1/3)(3*, 2/3)

(3*, 1/3)(3, 0)(3, 0)

Gauge bosons content

Gauge bosons content

Leptons masses

Leptons masses

Charged leptons masses

Leptons masses

Neutrinos Dirac massCharged leptons masses

Leptons masses

RH neutrinos scale

Neutrinos Dirac massCharged leptons masses

Leptons masses

So that neutrino masses arise from:

Mq' = 1 TeVMq' = 10 TeV

Does this model unify?

:-(

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2/3 Unification

The singlet gets a promotion

This breaks to the SM as (3, 0) + (2,1/2) + (2,-1/2) + (1,0)

(1, 0) (8, 0)

The singlet gets a promotion

(1, 0) (8, 0)

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3/3 "Gauge" Flavor symmetry

By virtue of anti-symmetry of the 3.3.3 product, the Dirac mass inherits a structure (+ lightest nu is massless). Flavor correlations?!!!!! !!!!!!

Flavor without flavor symmetry

By virtue of anti-symmetry of the 3.3.3 product, the Dirac mass inherits a structure (+ lightest nu is massless). Flavor correlations?!!!!! !!!!!!

Flavor without flavor symmetry

Mohapatra-Valle, 86'

By virtue of anti-symmetry of the 3.3.3 product, the Dirac mass inherits a structure (+ lightest nu is massless). Flavor correlations?!!!!!Flavor-changing radiative decay, via W, W', Phi, as a powerful probe:!!!!!

Flavor without flavor symmetry

Inverse-seesaw nu mass relation and antisymmetry of MD allow us to write the Dirac coupling in full generality as!!!!!!!!!which makes explicit the 1-to-1 relation LFV-oscillations parameters, up to a global scaling factor.!!!!!

Flavor without flavor symmetry

Flavor without flavor symmetry

There are 3 different contributions:!!

➢ Contributions from charged scalar exchange➢ "Standard" loops, via W and N ➢ Loops mediated by W'

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BR depend on: Ordering, osc. params, 331 scale, H+ scale, ms scale

Flavor predictions(331=3TeV, f=2TeV, NH, degenerate N)!!!

Flavor predictions - no scaling factor

(degenerate N)!!!

Summary

To summarize...

Ideally, the physics at the origin of neutrino masses should offer insights on other BSM problems!!Neutrino masses can arise from simple gauge loops in 3-3-1 extensions of the SM, which at the same time address other issues related to the flavor problem ! !This framework also offers flavor correlations due to the gauge structure itself, unification of gauge couplings, and rich pheno signatures: Z', B physics, LFV, etc.

To summarize...

Ideally, the physics at the origin of neutrino masses should offer insights on other BSM problems!!Neutrino masses can arise from simple gauge loops in 3-3-1 extensions of the SM, which at the same time address other issues related to the flavor problem ! !This framework also offers flavor correlations due to the gauge structure itself, unification of gauge couplings, and rich pheno signatures: Z', B physics, LFV, etc.

Thanks!

To summarize...

Ideally, the physics at the origin of neutrino masses should offer insights on other BSM problems!!Neutrino masses can arise from simple gauge loops in 3-3-1 extensions of the SM, which at the same time address other issues related to the flavor problem ! !This framework also offers flavor correlations due to the gauge structure itself, unification of gauge couplings, and rich pheno signatures: Z', B physics, LFV, etc.

Thanks!