On Minimal Models with Light Sterile Neutrinos Pilar Hernndez - - PowerPoint PPT Presentation

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On Minimal Models with Light Sterile Neutrinos Pilar Hernndez - - PowerPoint PPT Presentation

Jan 15, 2023 15 likes •497 views

On Minimal Models with Light Sterile Neutrinos Pilar Hernndez University of Valencia/IFIC Donini, Lpez-Pavn, PH, Maltoni arXiv:1106.0064 Donini, Lpez-Pavn, PH, Maltoni, Schwetz arXiv:1205.5230 SM + massive s Fogli et al 2012

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On Minimal Models with Light Sterile Neutrinos

Pilar Hernández University of Valencia/IFIC

Donini, López-Pavón, PH, Maltoni arXiv:1106.0064 Donini, López-Pavón, PH, Maltoni, Schwetz arXiv:1205.5230

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SM + massive νs

Fogli et al 2012 (after T2K, Double-CHOOZ, Daya Bay, RENO)

3ν mixing:

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Standard 3ν scenario

The flavour observables:

Masses Angles CP-phases m1

2 < m2 2, m3 2

θ12,θ23,θ13 δ, α1, α2

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Good prospects for CP volation

Coloma, Donini, Fernandez-Martinez,PH arXiv:1203.5651

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New dofs needed !

Neutrinos are massive -> there must be new dofs in the SM

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New dofs needed

Neutrinos are massive -> there must be new dofs in the SM

Weinberg

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?

SM νSM

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The good νSM

  • How does the ν scale relates to the EW scale ?
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The good νSM

  • New scale versus EWSB ?

Besides the consistency of SM, now the Higgs…where does the new scale fit in this picture ?

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The good νSM

  • New scale versus EWSB ?
  • Explanation for the neutrino-charged lepton

hierarchy

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The ν flavour puzzle I

Why are neutrino masses so light ?

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Seesaw of type I

Yukawa Λ = TeV Λ = GUT

Minkowski; Gell-Mann, Ramond Slansky; Yanagida, Glashow…

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The good νSM

  • New scale versus EWSB ?
  • Explanation for the neutrino-charged lepton

hierarchy

  • Explain difference lepton/quark mixing
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CKM PMNS

Gonzalez-Garcia, Maltoni PDG 2007 VCKM = Differences are striking!

The ν flavour puzzle II

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The good νSM

  • New scale versus EWSB ?
  • Explanation for the neutrino-charged lepton

hierarchy

  • Explain the difference lepton/quark mixing(probably

a very relevant question is how many ν dofs)

  • Explain other open problems: DM, matter-

antimatter, oscillation anomalies, cosmology anomalies…

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The good νSM

  • New scale versus EWSB ?
  • Explanation for the neutrino-charged lepton

hierarchy

  • Explain the difference lepton/quark mixing
  • Explain other open problems: DM, matter-

antimatter, oscillation anomalies, cosmology anomalies…

  • Do so, in a predictable and testable

way !

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Pinning down the New physics scale

TeV GeV MeV keV eV Leptogenesis Hierarchy problem or SUSY ? SUSY GUTs meV

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Pinning down the New physics scale

TeV GeV MeV keV eV CMB, LSS Leptogenesis LFV processes, Precision tests,LHC Hierarchy problem or SUSY ? SUSY GUTs meV Neutrino osc. Nucleosynthesi, SNs ββ0ν Baryogenesis Light Sterile Neutrinos White Paper, Abazajian et al arXiv: 1204.5379 and refs. therein

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Other uses of the New physics scale(s)

TeV GeV MeV keV eV Warm DM ? Hierarchy ? GUT ? meV LSND, reactor anomalies? Extra radiation ? Matter/antimatter asymmetry ?

New dofs might help resolve open problems…or be excluded by

  • bservations
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Outlier I: LSND anomaly

  • LSND vs KARMEN

Appearance signal with very different

Not yet disproved at an acceptable level of confidence…

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Outlier II: Cosmology

Sterile species favoured by LSS and CMB Nucleosynthesis:

Hamann et al, ArXiv: 1006.5276 Izotov, Thuan

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In order to accommodate a new

  • Need at least four (ns ≥ 1) distinct eigenstates
  • Apparently CP violating effect needed

(signal LSND/MB anti-ν not MB ν) ns ≥ 2 (seems not the case with new MiniBOONE data…)

  • Tension appearance (signal) and disappearance (no signal) ?
  • Tension with cosmology ?

LSND anomaly

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P(νe -> νµ) = O(|Uei|2 |Uµi|2) P(νµ -> νµ) = O(|Uµi|2) P(νe -> νe) = O(|Uei|2)

Oscillation terms associated with the larger mass splittings… A convincing signal would be to find it in all the three…

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Outlier III: reactor anomaly

Re-calculation of reactor fluxes:

  • ld fluxes underestimated by 3%:

Mueller et al, ArXiv: 1101.2663

Still to be confirmed by the new reactor experiments !

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3+2 neutrino mixing model

Parametrized in terms of a general unitary 5x5 mixing matrix (9 angles, 5 phases physical)

Kopp, Maltoni, Schwetz (KMS) arXiv:1103.4570 Giunti, Laveder, (GL) arXiv:1107.1452

Significant improvement over 3ν scenario, but tension appearance/disappearance remains

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What is this Pheno 3+ns mixing model ?

Assumes a general mass matrix for 3+ns neutrinos: 3xns 3x3

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Assumes a general mass matrix for 3+ns neutrinos:

Gauge invariance Effective theory: MLL parametrizes our ignorance about the underlying dynamics UV extension 1: a model with nR >= 3+ns , where 3 heavier states are integrated out UV extension 2: a model with nR = 3 + 2 ns and an exact lepton number....

What is this Pheno 3+ns mixing models ?

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Type I Seesaw

Most general (renormalizable) Lagrangian compatible with SM gauge symmetries:

Y: 3 x nR MN: nRx nR ms mν

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Ye

One scale see-saw models

Light sterile neutrinos

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3+nR Minimal Models

3+2 Minimal Model much more predictive than 3+2 Phenomenological Model

  • 3

Mini-seesaw models De Gouvea & coll. hep-ph/0501039, hep-ph/0608147

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On parametrizations

  • Independent (physical) parameters only
  • Convenient to impose existing constraints
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Casas-Ibarra parametrization

For mi << Mj

Unitary Complex orthogonal If M ≤ O(eV) corrections are important !

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Beyond Casas-Ibarra

More generally (extended Casas-Ibarra)

Donini, et al 1205.5230

Incorporates the expected non-unitarity effects in the light sector

Blennow, Fernandez-Martinez arXiv:1107.3992

Alternative parametrization same philosophy

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Inverse Hierarchy Normal Hierarchy

Heavy-light mixings are predicted up to a complex angle z45 and two CP phases !

Heavy-Light Mixings

Suppressed in and Suppressed only in Donini, et al 1106.0064; de Gouvea, Huang 1110:6122;Fan,Langacker 1201:6662 Right ballpark! Ex:

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Global fits

  • Not possible to decouple LBL and SBL analyses: too

large correlations in Uaa and Uas

  • Need to include corrections to Casas-Ibarra-> more

general parametrization

  • Use M1, M2 from KMS and GL fits
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3+2 MM vs 3+2 PM vs 3ν

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e µ τ Large tau mixings to heavy states

Heavy-Light Mixings

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Constraint on Constraint on

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Significant improvement over 3ν scenario, but large tension appearance/disappearance in µ sector remains (MINOS CC high energy) Tension with cosmology that favours extra but lighter states Should be easy to clarify…

BUT….

T2K ND

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?

Even if LSND not correct we should clarify whether the picture does not look like …

Hierarchy ?

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Minimal models

Most general (renormalizable) Lagrangian compatible with SM gauge symmetries:

Y: 3 x nR MN: nRx nR

Number of Physical Parameters 1 Dirac 2 Dirac 3 Dirac Complexit y predictivity 3+1 minimal 3+2 minimal

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Minimal 3+1

Two massless +two massive eigenstates, only two physical angles, no CP violation Strong incompatibility between Chooz+KamLAND vs Chooz+MINOS

Donini et al 1106.0064

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Minimal 3+2

Degerate case: M1 = M2 = M, 3 angles, no CP violation

Eigenstates

Dirac seesaw mD+ mD- M MSS

min

MQD

max

atm sol atm sol

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SOLAR data: MQD

max

Impressive sensitivity of solar neutrinos to tiny departures from diracness!

See also De Gouvea, Huang, Jenkins arXiv: 0906.1611

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LBL data: MSS

min

M > 0.6 eV (NH), 1.4eV (IH) as good fits as 3ν scenario

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Conclusions

  • Minimal models of neutrino masses are also models with

extra sterile states but ones that are much more constrained/predictive than those used in phenomenological fits

  • They have a rich phenomenology if their mass is below the EW scale
  • This phenomenology has to be explored systematically
  • Optimistically we might solve some other problem…or at least

severely constraint the ν physics scale

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SOLAR data: MQD

max

Adiabatic approx. IH Adiabaticity limit: Vaccuum oscillations:

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3+2 PM, KMS fit