Ternary generalizations of graded algebras and their applications in physics
We discuss cubic and ternary algebras which are a direct generalization of Grassmann
and Clifford algebras, but with $Z_3$-grading replacing the usual $Z_2$-grading.
Elementary properties and structures of such algebras are discussed, with special interest
in low-dimensional ones, with two or three generators.
Invariant antisymmetric quadratic and cubic forms on such algebras are introduced, and it
is shown how the $SL(2,C)$ group arises naturally in the case of lowest dimension, with
two generators only, as the symmetry group preserving these forms.
We also show how the calculus of differential forms can be extended to include also second
differentials $d^2 x^i$, and how the $Z_3$ grading naturally appears when we assume that
$d^3 = 0$ instead of $d^2 = 0$.
Ternary analogue of the commutator is introduced, and its relation with usual Lie algebras
investigated, as well as its invariance properties.
We shall also discuss certain physical applications In particular, $Z_3$-graded gauge theory
is briefly presented, as well as ternary generalization of Pauli's exclusion principle and
ternary Dirac equation for quarks.