On Minimal Models with Light Sterile Neutrinos

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1 On Minimal Models with Light Sterile Neutrinos Pilar Hernández University of Valencia/IFIC Donini, López-Pavón, PH, Maltoni arxiv: Donini, López-Pavón, PH, Maltoni, Schwetz arxiv:

2 SM + massive ν s Fogli et al 2012 (after T2K, Double-CHOOZ, Daya Bay, RENO) 3ν mixing:

3 Standard 3ν scenario The flavour observables: Masses Angles CP-phases m 12 < m 22, m 3 2 θ 12,θ 23, θ 13 δ, α 1, α 2

4 Good prospects for CP volation Coloma, Donini, Fernandez-Martinez,PH arxiv:

5 New dofs needed! Neutrinos are massive -> there must be new dofs in the SM

6 New dofs needed Neutrinos are massive -> there must be new dofs in the SM Weinberg

7 SM νsm?

8 The good νsm How does the ν scale relates to the EW scale?

9 The good νsm New scale versus EWSB? Besides the consistency of SM, now the Higgs where does the new scale fit in this picture?

10 The good νsm New scale versus EWSB? Explanation for the neutrino-charged lepton hierarchy

11 The ν flavour puzzle I Why are neutrino masses so light?

12 Seesaw of type I Minkowski; Gell-Mann, Ramond Slansky; Yanagida, Glashow Λ = TeV Yukawa Λ = GUT

13 The good νsm New scale versus EWSB? Explanation for the neutrino-charged lepton hierarchy Explain difference lepton/quark mixing

14 CKM The ν flavour puzzle II V CKM = PDG 2007 PMNS Gonzalez-Garcia, Maltoni Differences are striking!

15 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, matterantimatter, oscillation anomalies, cosmology anomalies

16 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, matterantimatter, oscillation anomalies, cosmology anomalies Do so, in a predictable and testable way!

17 Pinning down the New physics scale Hierarchy problem or SUSY? mev ev kev MeV GeV TeV Leptogenesis SUSY GUTs

18 Pinning down the New physics scale ββ0ν Neutrino osc. LFV processes, Precision tests,lhc Hierarchy problem or SUSY? mev ev kev MeV GeV TeV CMB, LSS Nucleosynthesi, SNs Baryogenesis Leptogenesis SUSY GUTs Light Sterile Neutrinos White Paper, Abazajian et al arxiv: and refs. therein

19 Other uses of the New physics scale(s) Warm DM? Hierarchy? mev ev kev MeV GeV TeV LSND, reactor anomalies? Extra radiation? Matter/antimatter asymmetry? GUT? New dofs might help resolve open problems or be excluded by observations

20 Outlier I: LSND anomaly LSND vs KARMEN Appearance signal with very different - Not yet disproved at an acceptable level of confidence

21 Outlier II: Cosmology Sterile species favoured by LSS and CMB Hamann et al, ArXiv: Nucleosynthesis: Izotov, Thuan

22 LSND anomaly In order to accommodate a new Need at least four (n s 1) distinct eigenstates Apparently CP violating effect needed (signal LSND/MB anti-ν not MB ν) n s 2 (seems not the case with new MiniBOONE data ) Tension appearance (signal) and disappearance (no signal)? Tension with cosmology?

23 Oscillation terms associated with the larger mass splittings P(ν e -> ν µ ) = O( U ei 2 U µi 2 ) P(ν µ -> ν µ ) = O( U µi 2 ) P(ν e -> ν e ) = O( U ei 2 ) A convincing signal would be to find it in all the three

24 Outlier III: reactor anomaly Re-calculation of reactor fluxes: old fluxes underestimated by 3%: Mueller et al, ArXiv: Still to be confirmed by the new reactor experiments!

3+2 neutrino mixing model Parametrized in terms

25 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: Giunti, Laveder, (GL) arxiv: Significant improvement over 3ν scenario, but tension appearance/disappearance remains

26 What is this Pheno 3+n s mixing model? Assumes a general mass matrix for 3+n s neutrinos: 3x3 3xn s

27 What is this Pheno 3+n s mixing models? Assumes a general mass matrix for 3+n s neutrinos: Gauge invariance Effective theory: M LL parametrizes our ignorance about the underlying dynamics UV extension 1: a model with n R >= 3+n s, where 3 heavier states are integrated out UV extension 2: a model with n R = n s and an exact lepton number...

28 Type I Seesaw Most general (renormalizable) Lagrangian compatible with SM gauge symmetries: Y: 3 x n R M N : n R x n R m ν m s

29 One scale see-saw models Light sterile neutrinos Y e

30 3+n R Minimal Models 3+2 Minimal Model much more predictive than 3+2 Phenomenological Model -3 Mini-seesaw models De Gouvea & coll. hep-ph/ , hep-ph/

31 On parametrizations Independent (physical) parameters only Convenient to impose existing constraints

32 Casas-Ibarra parametrization For m i << M j Unitary Complex orthogonal If M O(eV) corrections are important!

33 Beyond Casas-Ibarra More generally (extended Casas-Ibarra) Donini, et al Incorporates the expected non-unitarity effects in the light sector Alternative parametrization same philosophy Blennow, Fernandez-Martinez arxiv:

34 Normal Hierarchy Heavy-Light Mixings Heavy-light mixings are predicted up to a complex angle z 45 and two CP phases! Ex: Suppressed in and Inverse Hierarchy Suppressed only in Right ballpark! Donini, et al ; de Gouvea, Huang 1110:6122;Fan,Langacker 1201:6662

35 Global fits Not possible to decouple LBL and SBL analyses: too large correlations in U aa and U as Need to include corrections to Casas-Ibarra-> more general parametrization Use M 1, M 2 from KMS and GL fits

36 3+2 MM vs 3+2 PM vs 3ν

37 Heavy-Light Mixings e µ τ Large tau mixings to heavy states

38 Constraint on Constraint on

39 BUT. 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 T2K ND

40 Even if LSND not correct we should clarify whether the picture does not look like? Hierarchy?

41 Minimal models Most general (renormalizable) Lagrangian compatible with SM gauge symmetries: Y: 3 x n R M N : n R x n R Number of Physical Parameters Complexit y predictivity 3+1 minimal 1 Dirac 3+2 minimal 2 Dirac 3 Dirac

42 Minimal 3+1 Two massless +two massive eigenstates, only two physical angles, no CP violation Donini et al Strong incompatibility between Chooz+KamLAND vs Chooz+MINOS

43 Minimal 3+2 Degerate case: M 1 = M 2 = M, 3 angles, no CP violation Eigenstates m D+ Dirac seesaw atm m D- sol M QD max M SS min sol M atm

44 SOLAR data: M QD max Impressive sensitivity of solar neutrinos to tiny departures from diracness! See also De Gouvea, Huang, Jenkins arxiv:

45 LBL data: M SS min M > 0.6 ev (NH), 1.4eV (IH) as good fits as 3ν scenario

46 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

47 SOLAR data: M QD max IH Adiabatic approx. Adiabaticity limit: Vaccuum oscillations:

48 3+2 PM, KMS fit

Cosmological constraints on the Sessaw Scale

Cosmological constraints on the Sessaw Scale Jacobo López-Pavón 50th Rencontres de Moriond EW La Thuile, Valle d'aosta (Italy) 14-21 March, 2015 Motivation Which is the simplest extension of the SM that