Morimitsu TANIMOTO

1
Prediction of Ue3 and cos?23 from Discrete
symmetry

• Morimitsu TANIMOTO
• Niigata University, Japan

XXXXth RENCONTRES DE MORIOND March 6, 2005 _at_ La
Thuile, Aosta Valley, Italy
Based on the work by W.Grimus, A.Joshipura,
S.Kaneko, L.Lavoura, H.Sawanaka and M.Tanimoto,
Nucl. Phys. B, 2005 (hep-ph/0408123)
2
I. Introduction
Neutrino Mixings are near Bi-Maximal
3
Questions
? Why are ?23 and ?12 so large ?
? Why does sin?12 deviate from maximal although
sin?23 is almost maximal ?
? Why is ?13 small ? How small
is?13 ?
Expectation
? Flavor Symmetry prevents non-zero ?13
4
Plan of the talk
1. Introduction
2. Vanishing Ue3 and Discrete Symmetry
3. Symmetry Breaking and Neutrino Mixing Angles
Grimus, Joshipura, Kaneko, Lavoura,
Sawanaka and Tanimoto Nucl. Phys.
B(2005) hep-ph/0408123
4. Summary and Discussions
5
2. Vanishing Ue3 and Discrete Symmetry

• Basic Idea Naturalness of Theory
• Suppose a dimensionless small parameter a.
  If a 0, the Symmetry is enhanced.

Neutrino Mass Matrix is constructed
in terms of neutrino masses and mixings
m1, m2, m3
6

• which has Z2 Symmetry

7
(No Transcript)
8
In the limit?2?23 p/2, ?13 0