Eg. Kalnins et W. Miller, Q-ALGEBRA AND Q-SUPERALGEBRA TENSOR-PRODUCTS AND IDENTITIES FOR SPECIAL FUNCTION, Physics of atomic nuclei, 61(10), 1998, pp. 1659-1665
Tensor products are constructed for distinct q generalizations of Eucl
idean oscillator- and sl(2)-type algebras and superalgebras, including
cases where the method of highest weight vectors does not apply. In p
articular, three-term recurrence relations for Askey-Wilson polynomial
s are used to decompose the tensor product of representations from pos
itive discrete series and representations from negative discrete serie
s. It is shown that various q analogs of the exponential function can
be used to mimic the exponential mapping from a Lie algebra to its Lie
group, and the corresponding matrix elements of the group operators o
n these representation spaces are computed. The most important q-serie
s identities derived here are interpreted as the expansion of the matr
ix elements of a group operator (via exponential mapping) in a tenser-
product basis in terms of the matrix elements in a reduced basis. They
involve q-hypergeometric series with base q and -q, respectively, for
the algebra and superalgebra cases, where 0 < q < 1.