Let T be an underlying space with a non-atomic measure σ on it. In [Comm. Math. Phys. 292 (2009), 99-129] the Meixner class of non-commutative generalized stochastic processes with freely independent values, ω = (ω(t)) t∈T , was characterized through the continuity of the corresponding orthogonal polynomials. In this paper, we derive a generating function for these orthogonal polynomials. The first question we have to answer is: What should serve as a generating function for a system of polynomials of infinitely many non-commuting variables?We construct a class of operator-valued functions Z = (Z(t)) t∈T such that Z(t) commutes with ω(s) for any s, t ∈ T . Then a generating function can be understood as G(Z, ω) = ∞ n=0 T n P (n) (ω(t 1 ), . . . , ω(t n ))Z(t 1 ) · · · Z(t n )σ(dt 1 ) · · · σ(dt n ), where P (n) (ω(t 1 ), . . . , ω(t n )) is (the kernel of the) n-th orthogonal polynomial. We derive an explicit form of G(Z, ω), which has a resolvent form and resembles the generating function in the classical case, albeit it involves integrals of non-commuting operators. We finally discuss a related problem of the action of the annihilation operators ∂ t , t ∈ T . In contrast to the classical case, we prove that the operators ∂ t related to the free Gaussian and Poisson processes have a property of globality. This result is genuinely infinite-dimensional, since in one dimension one loses the notion of globality.
Construction of integral of an operator-valued functionwith respect to an operator-valued measure Let G be a real separable Hilbert space, and let L (G) denote the Banach space of all bounded linear operators in G. We will call a mapping Z : T → L (G) simple if it has