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Unveiling Neutrino Mysteries: The Zee Model Revealed

Explore the mysterious world of neutrino physics, uncovering the origins of neutrino masses and their particle nature. Delve into the Zee Model's unique framework with global U(1) symmetry to solve these enigmas. Discover the implications of CP-violation, mass hierarchy, and more with this groundbreaking research.

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Unveiling Neutrino Mysteries: The Zee Model Revealed

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  1. Zee Model with a Flavor Dependent Global U(1) Symmetry Kei Yagyu Osaka U. Collaboration with Takaaki Nomura (KIAS) 1905.XXXXX [hep-ph] 2019,May.27th, 7th RISE Collaboration Workshop

  2. Neutrinos as the Evidence of BSM • Neutrino physics shows the clear evidence of BSM, and it is still mysterious. ・What is the origin of tiny neutrino masses? ・Are neutrinos Majorana or Dirac particles? τ,c,b μ t e E ・Which are the correct mass hierarchy, Normal or Inverted? keV MeV GeV eV ・Does the neutrino sector contain CP-violation? http://www.hyper-k.org

  3. Neutrinos as the Evidence of BSM • Neutrino physics shows the clear evidence of BSM, and it is still mysterious. ・What is the origin of tiny neutrino masses? ・Are neutrinos Majorana or Dirac particles? τ,c,b μ t e E ・Which are the correct mass hierarchy, Normal or Inverted? keV MeV GeV eV ・Does the neutrino sector contain CP-violation? Inmytalk, ... http://www.hyper-k.org

  4. Neutrino Mass Generations Weinberg (1979) • Majorana neutrino masses are described by a dimension 5 operator v v Φ Φ ν ν ν ν L L L L • From ν experiments, mν should be O(0.1) eV. M ~ O(1015) GeV if C ~ 1. Eg., C ~ O(10-8)if M ~ v.

  5. Renormalizable Models Mikowski (1977), Yanagida, Gell-Mann (1979) Mohapatra, Senjanovic (1980) • The type-I seesaw mechanism y y ν ν ν • Radiative seesaw mechanism L L R Usually, more suppressions like (ml/v)p can appear depending on a model. Loop structure

  6. Renormalizable Models Mikowski (1977), Yanagida, Gell-Mann (1979) Mohapatra, Senjanovic (1980) • The type-I seesaw mechanism y y ν ν ν • Radiative seesaw mechanism L L R Usually, more suppressions like (ml/v)p can appear depending on a model. Loop structure

  7. Radiative Seesaw Models :Lepton # line ✖：VEV :Lepton # Violation (2 units) :Exact Z2 line Zee (1980) Zee-Babu (1986) Ma (2006) Aoki-Kanemuera-Seto (2009) Krauss-Nasri-Trodden (2003)

  8. The Zee Model Zee, PLB93, 389 (1980) • Only the Higgs sector is extended from the SM (No RH neutrino) • Higgs sector:2-Higgsdoublets (Φ1, Φ2) + charged singlet (S±) • A softly-broken Z2 symmetry is imposed (Zee-Wolfenstein model).

  9. The Zee Model Zee, PLB93, 389 (1980) • Only the Higgs sector is extended from the SM (No RH neutrino) • Higgs sector:2-Higgsdoublets (Φ1, Φ2) + charged singlet (S±) • A softly-broken Z2 symmetry is imposed (Zee-Wolfenstein model).

  10. The Zee Model Zee, PLB93, 389 (1980) • Only the Higgs sector is extended from the SM (No RH neutrino) • Higgs sector:2-Higgsdoublets (Φ1, Φ2) + charged singlet (S±) • A softly-broken Z2 symmetry is imposed (Zee-Wolfenstein model). For tanβ = 1, mH2(1) = 400 (300) GeV, ml = mμ.

  11. Neutrino Mixing c.f. F : anti-symmetric For V13≪ 1, only the IH is possible. x > 0 [N.H.] x < 0 [I.H.] BUT

  12. Zee model with Type-III Yukawa • In this way, the simple Zee model has been excluded. Hasegawa, Lim, Ogure, 0303252 (PRD) He, 0307172 (EPJC) Sierra, Restrepo, 0604012 (JHEP) Garcca, Ohlsson, Riad, Wirn, 1701.05345 (JHEP), Etc… • A way out is to forget about the Z2 symmetry. • We can explain neutrino mixings, • but we have many parameters and the quark sector may also have FCNCs….

  13. We solved these two problems at the same time by a simple extension!!

  14. Our Extension Same particle content Global U(1) symmetry w/ flavor dependent charges This kind of model has been known as Branco-Grimus-Lavoura (BGL) models.

  15. Our Extension Same particle content Global U(1) symmetry w/ flavor dependent charges This kind of model has been known as Branco-Grimus-Lavoura (BGL) models. • Yukawa interaction Only Φ2 couples to quarks → No tree level FCNCs The structure of these couplings depend on the charge assignment.

  16. Structure of the Yukawa Matrices • Class I : qR =(0,0,-q), qL = qS = 0 • Class II : qR =0, qL = (0,0,q), qS = -q • Class III : qR =(0,0,-q), qL = (0,0,-2q), qS = q

  17. Analysis Neutrino masses Charged lepton masses

  18. LFVs of charged leptons Preliminary sin(β-α) = 1 mH = mA = mH1+ = 800 GeV mH2+ = 1000 GeV γ h, H, A H1±, H2± l’ l l’ l γ Inverted Hierarchy Normal Hierarchy

  19. LFV Higgs Decays Preliminary sin(β-α) = 1 mH = mA = mH1+ = 800 GeV, mH2+ = 1000 GeV H decay Normal Hierarchy Inverted Hierarchy In the NH case, BR(H → eτ) ≳ BR(H → eμ)

  20. Summary https://www.forbes.com/sites/brentbeshore/2013/04/17/ how-killing-two-birds-with-one-stone-kills-us-and-our-work/ • We got “2 birds with 1 stone”. Global U(1) symmetry Preliminary Another source of LFV No FCNCs in the quark sector • Characteristic pattern in the LFV Higgs decays • can appear. It can be a smoking gun sig. at LHC!

  21. LFV Higgs Decays sin(β-α) = 1, mH = 300 GeV Normal Hierarchy Inverted Hierarchy

  22. LFV Higgs Decays Normal Hierarchy Inverted Hierarchy

  23. Neutrino masses Class I Class II

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