A. Sergeev, Enveloping superalgebra U(osp (1 vertical bar 2)) and orthogonal polynomials in discrete indeterminate, J NONL M PH, 8(2), 2001, pp. 229-255
Let A be an associative simple (central) superalgebra over C and L an invar
iant linear functional on it (trace). Let a bar right arrow a(t) be an anti
automorphism of A such that (a(t))(t) = (-1)(p(a))a, where p(a) is the pari
ty of a, and let L(a(t)) = L (a). Then A admits a nondegenerate supersymmet
ric invariant bilinear form <a,b > = L(ab(t)). For A = U(sl( 2))/m, where m
is any maximal ideal of U(sl( 2)), Leites and I have constructed orthogona
l basis in A whose elements turned out to be, essentially, Chebyshev ( Hahn
) polynomials in one discrete variable. Here I take A = U(osp(1|2))/m for a
ny maximal ideal m and apply a similar procedure. As a result we obtain eit
her Hahn polynomials over C[tau], where tau (2) epsilon C, or a particular
case of Meixner polynomials, or - when A = Mat( n+1|n)- dual Hahn polynomia
ls of even degree, or their ( hopefully, new) analogs of odd degree. Observ
e that the nondegenerate bilinear forms we consider for orthogonality are,
as a rule, not sign definite.