Vk. Dobrev et R. Floreanini, THE MASSLESS REPRESENTATIONS OF THE CONFORMAL QUANTUM ALGEBRA, Journal of physics. A, mathematical and general, 27(14), 1994, pp. 4831-4840
The massless representations of the conformal quantum algebra U(q)(su(
2, 2)) for complex q such that Absolute value of q = 1 are studied in
detail. By factorizing out all singular vectors of the corresponding V
erma modules, a simple basis for these representations is explicitly c
onstructed. This basis is new also for the usual conformal algebra su(
2, 2). This construction allows a straightforward treatment of the cas
e q a root of unity, when the representations are unitary and finite-d
imensional.