Speaker
Prof.
Fuminobu Takahashi
(Tohoku University)
Description
We propose that the stability of dark matter is ensured by a discrete subgroup of the
U(1)B-L gauge symmetry, Z_2(B-L). We introduce a set of chiral fermions charged
under the U(1)B-L in addition to the right-handed neutrinos, and require the anomaly-
cancellation conditions associated with the U(1)B-L gauge symmetry. We find that the
possible number of fermions and their charges are tightly constrained, and that non-
trivial solutions appear when at least five additional chiral fermions are introduced. The
Fermat theorem in the number theory plays an important role in this argument.
Focusing on one of the solutions, we show that there is indeed a good candidate for
dark matter, whose stability is guaranteed by Z_2(B-L).
Primary author
Prof.
Fuminobu Takahashi
(Tohoku University)
