1 / 33

Golden Littlest Seesaw

Golden Littlest Seesaw. Gui -Jun Ding. University of Science and Technology of China. Based on Nucl.Phys . B925 (2017) 470-499, arXiv:1705.05307 , in collaboration with Stephen F. King and Cai -Chang Li.

saddam
Télécharger la présentation

Golden Littlest Seesaw

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Golden Littlest Seesaw Gui-Jun Ding University of Science and Technology of China Based on Nucl.Phys. B925 (2017) 470-499, arXiv:1705.05307, in collaboration with Stephen F. King and Cai-Chang Li Workshop on String, Field Theory and Gravitational Wave , November 26th, 2017, Chuzhou, China

  2. Neutrinos are everywhere! SM Big Bang Human neutrinos Galaxy Supernova Earth Reactor Sun Accelerator

  3. Neutrino Mixing In the framework of 3ν mixing Majorana CP phases Reactor mixing & Dirac CP phase Solar mixing Atmospheric mixing

  4. Where do we stand? Taken from NuFIT, arXiv: 1611.01514 Unknown quantities: ①The octant of θ23 ② CP phases: δCP , α21 and α31 ③ neutrino mass order.

  5. Flavor mixing puzzle in SM [Particle Data Group 2016] Quarks: Leptons: [Esteban et al, JHEP 01 (2017) 087]

  6. Scheme to predict lepton mixing from flavor and CP charged lepton neutrino [Lu, Ding, Phys.Rev. D95 (2017) no.1, 015012; Li, Lu, Ding, arXiv:1706.04576]

  7. Extending to the quark sector Left-handed quarks transform as a triplet of the group Gf down quarks up quarks • Four observables: three quark mixing angles+one CP phase are predicted in terms of two parameters θ1,2

  8. Results: Large neutrino mixing angles and small quark mixing angles can be accommodated simultaneously by the Δ(6n2) flavor group. Δ(6∙72) with n=7 is the smallest group. • Quark sector : for VII,2 • Lepton sector : for UII,4 [Li, Lu, Ding, arXiv:1706.04576]

  9. Observation of CP violating phase @T2K and NOva [NOvA Collaboration,Phys. Rev. Lett. 118, 231801 (2017)] [T2K Collaboration, Phys. Rev. Lett. 118, 151801 (2017)] The best fit points lie near the maximally CP violating value δCP=-0.5π

  10. Type I seesaw mechanism • Adding right-handed neutrinos with Yukawa couplings y and a Majorana mass term M after spontaneous symmetry breaking mD= yv In the seesaw limit M >> mD [Minkowski(1977); Yanagida(1979); Glashow (1979); Gell-Mann, Ramond, Slansky(1979); Mohapatra, Senjanovic(1980)]

  11. Littlest Seesaw Model • Diagonal charged lepton basis • Two right-handed neutrinos diagonal • Three lepton doubletstransform as triplet of flavor symmetry The light neutrino mass matrix is given by the seesaw formula • Vacuum alignment [King,JHEP 1602 (2016) 085]

  12. One one phase • Benchmark model: n=3, =2/3 [Ballett,King,Pascoliet al,JHEP1703 (2017) 110]

  13. A5 flavor group The A5 group is isomorphic to the symmetry of a regular dodecahedron and a regular icosahedron. 60 elements are generated S and T: Irreducible representations: 1, 3, 3′, 4 , 5 • The three generation of left-handed lepton are assigned to triplet 3 Golden Ratio􀀃

  14. Direct approach [Altarelli, Feruglio, Rev.Mod.Phys. 82 (2010) 2701] • The lepton flavor mixing arises from the mismatch between the residual subgroups Gland Gν in charged lepton and neutrino sectors.

  15. Direct approach in A5 Suppose A5 is spontaneously broken to the subgroups: Charged lepton sector preserves Neutrino sector preserves Mixing matrices diagonalizingalso diagonalize and , respectively ! Golden ratio mixing θ13=0 [Ding, Everett and Stuart, Nucl. Phys. B 857, 219 (2012)]

  16. Golden Littlest Seesaw

  17. Example of golden Littlest seesaw • A5 is broken to different subgroups Charged lepton sector preserves Atmospheric neutrino sector preserves Solar neutrino sector preserves • Vacuum alignment • Mass matrices The charged lepton mass matrix is diagonal because Tis diagonal in our basis.

  18. After seesaw Three parameters ma, mb, ηexplain nine observables (3 neutrino masses+ 3 mixing angles+3 CP phases). • The neutrino mass spectrum is normal ordering and lightest one is massless m1=0 • GR1 mixing with non-zero θ13

  19. [Ding,King,Li,Nucl.Phys. B925 (2017) 470 ]

  20. Model building of Golden Littlest seesaw [Ding,King,Li,Nucl.Phys. B925 (2017) 470 ] • Field content

  21. Charged lepton sector • Charged lepton mass matrix is diagonal • Hierarchical charged lepton masses • Higher order corrections appear at relative order 1/Λ3

  22. Neutrino sector After flavor and EW symmetry breaking, the neutrino Dirac and Majorana mass matrices read with Golden Littlest seesaw is reproduced exactly.

  23. Summary A unified description of quark and lepton mixing can be achieved if the flavor and CP symmetries are broken to Z2xCP in all sectors, Δ(6∙72) =Δ(294) is a good candidate for flavor symmetry. We propose a new model building paradigm and apply it to A5 Implication of this proposal in leptogenesis? new lepton mixing patterns and new models? Thank you for your attention!

  24. Backup

  25. Model building of Golden Littlest seesaw [Ding,King,Li,Nucl.Phys. B925 (2017) 470 ] • Field content • Flavon potential

  26. Origin of neutrino masses If neutrinos are Majorana particles, the effective mass operators are • tree level UV completion--- seesaw mechanism Type-I:SM+singlet fermionNR Type-II:SM+triplet scalar Δ Type-III:SM+tripletfermionΣ Minkowski(1977); Yanagida(1979); Glashow (1979); Gell-Mann, Ramond, Slansky(1979); Mohapatra, Senjanovic(1980) Magg, Wetterich(1980); Schechter, Valle (1980); Mohapatra, Senjanovic(1980) Foot, Lew, He, Joshi (1989)

  27. One-Loop realizations: only 4 independent topologies [Bonnet,Hirsch,Ota,Winter, JHEP 1207 (2012) 153] Zee model[A. Zee, Phys.Lett. B93, 389 (1980)] • neutrino masses are suppressed by loop factors • at least 2 new multiplets required as intermediate states • The intermediate states could be light and probed at existing facilities (the fermionsingletsNR in seesaw are at the GUT scale) For recent review: Yi Cai, Raymond R. Volkas et al, arXiv:1706.08524

  28. two-Loop realizations: 20 independent topologies [Sierra,Degee,Dorame, Hirsch, JHEP 1503, 040 (2015)]

  29. If neutrinos are Dirac particles, the effective mass operators are • Lowest order contribution→d=4 tree level one-loop level [Ma,Popov,Phys.Lett.B764 (2017)142; Yao, Ding, arXiv:1707.09786] The fermion mass hierarchy problem is worsened.(i.e., mi/mt< 10-12)

  30. Next to lowest order contribution→d=6 • tree level realization : 4 independent topologies F1 F2 F3 F4 • One-loop realization : 6 independent topologies

  31. Fields assignments • trilinear couplings: nXis the SU(2) representation of the field X. • four-point vertex:

  32. Example models There are 16 diagrams which can forbid both lower order tree level and one-loop diagrams. Loop integral

  33. One stone kills two birds: intermediate states can be dark matter candidates • chargeless: • direct detection bound: • stability: particles in the loop are odd under Z2 and others are even

More Related