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Higher dimensional seesaw. Atsushi WATANABE. Niigata Univ. & The Max-Planck-Institute for Nuclear Physics. Based on the work with K. Yoshioka (Kyoto Univ.) , H. Ishimori , Y. Shimizu, M. Tanimoto (Niigata Univ.). 23 rd February 2011 @ HRI, Allahabad. Contents. Neutrino mass.
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Higher dimensional seesaw Atsushi WATANABE Niigata Univ. & The Max-Planck-Institute for Nuclear Physics Based on the work with K. Yoshioka (Kyoto Univ.), H. Ishimori, Y. Shimizu, M. Tanimoto (Niigata Univ.) 23rd February 2011 @ HRI, Allahabad
Neutrino mass The bulk right-handed neutrinos [Dienes,Dudas,Gherghetta,1999] [Arkani-Hamed,Dimopoulos,Dvali,March-Russell,1999] Standard Model + gravity SM right-handed neutrinos • Suppressed Dirac mass An interesting range of the neutrino mass shows up
(SM) Localizationof the wave function [Grossman, Neubert, 99] [Chang, Hisano, Nakano, Okada, Yamaguchi, 99]
Neutrino mass after the seesaw Seesaw in five dimensions [Dienes,Dudas,Gherghetta,99] [Lukas, Ramond, Romanino, Ross, 00] SM
Options available in 5D SM ■ The mass terms (Majorana, Dirac, Lorentz-violating …) ■ The bulk geometry (Flat, Warped, Others …) ■ The boundary conditions for the bulk fields
for eV neutrino mass Seesaw with the bulk Dirac mass Bulk Dirac [AW, Yoshioka, 2009]
small Inverse seesaw Zero mode is negligible in seesaw The zero mode function
On the warped geometry Planck (y=0) TeV (y=L) How does the background change the neutrino mass ?
By the usual KK expansion, … It is hard to perform seesaw diagonalization
The equations for the bulk propagator the warped effect is vanishing away at the low-energy limit
・ The neutrino mass is not much affected by the background ・ The result is the same for more general metric ・ The seesaw mass can be calculated without knowing the KK expansion Even with a complicated backgroud where a suitable KK expansion cannot be find, the seesaw neutrino mass is calculable.
Flavor symmetry breaking at the boundaries Irreducible representations: Exmaple of the triplet elements of the S4 group SM
Example I: ・ only one mixing angle ・ degenerate masses
Summary SM ・ Inverse seesaw (bulk Dirac mass) ・ Geometry free nature of the neutrino mass ・ Flavor symmetry breaking at the boundaries
Charged-lepton sector ⇒ small mixing for the left-handed direction