Neutrinos Again

A paper by Altarelli and Feruglio on tribimaximal mixing was mentioned in talks at Neutrino 08, so I thought I should take a look at it. They begin by describing the 3 dimensional representation of $A_4$ which has generators $S$ and $T$ satisfying $(ST{)}^3=S^2=1$, just like the modular group, and also the relation $T^3=1$. Then, letting $\omega$ be the cubed root of unity, one has for $T$ the matrix

1 0 0
0 ${\omega }^2$ 0
0 0 $\omega$

and for $3S$ the circulant matrix

-1 2 2
2 -1 2
2 2 -1

The 12 elements of $A_4$ are given by all possible combinations of these generators. Gee, it already sounds a bit like M Theory. I can't imagine what they want with all the fairy fields and SUSY's mumbo jumbo, although in short shrift the tribimaximal mixing matrix appears.