Abstract. An analogue of the star product, familiar from deformation quantization, is studied in the setting of real bounded symmetric domains. The analogue turns out to be a certain invariant operator, which one might call star restriction, from functions on the complexification of the domain into functions on the domain itself. In particular, we establish the usual (i.e. semiclassical) asymptotic expansion of this star restriction, and further obtain a real-variable analogue of a theorem of Arazy and Ørsted concerning the analogous expansion for the Berezin transform.
Covariant Calculi on Complex and Real Symmetric DomainsLet D = G/K be an irreducible bounded symmetric domain in C d in the HarishChandra realization, with G the identity connected component of the group of all biholomorphic self-maps of D and K the stabilizer of the origin; K can also be realized as the automorphism group Aut(Z) of the Hermitian Jordan triple Z ≈ C where dz stands for the Lebesgue measure, K(z, w) is the ordinary (unweighted) Bergman kernel of D, and c ν is a normalizing constant to make dµ ν a probability measure. The space, where J g denotes the complex Jacobian of the mapping g. (In general, if ν/p is not an integer, then U (ν) is only a projective representation due to the ambiguity in the choice of the power J g −1 (z) ν/p .) This situation will henceforth be called the complex bounded case.In addition to bounded symmetric domains, we will also consider the complex flat case of a Hermitian vector space In most cases, such calculi can be built by the recipewhere dµ 0 is a G-invariant measure on D, and A ζ is a family of operators in(One calls such a family a covariant operator field on D. One also usually normalizes the measure dµ 0 so that A 1 is the identity operator.) Note that in view of the transitivity of the action of G on D, any covariant operator field is uniquely determined by its value A 0 at the origin ζ = 0. The best known examples of such calculi are the Toeplitz calculus T and the Weyl calculus W, corresponding to T 0 = ·, 1 1 (the projection onto the constants) and W 0 f (z) = f (−z) (the reflection operator), respectively [2]. For the complex flat case, W is just the well-known Weyl calculus from the theory of pseudodifferential operators, see e.g. [12].Given a covariant operator calculus A, the associated star product * on functions on D is defined byWhile f * g is a well-defined object for some calculi (e.g. for A = W, at least on C d and rank one symmetric domains, see [4]), in most cases (e.g. for A = T , the Toeplitz calculus), it makes sense only for very special functions f, g and (7) is then usually understood as an equality of asymptotic expansions as the Wallach parameter ν tends to infinity. For instance, for A = T , it was shown in [6] that for any f, g ∈ C ∞ (D) with compact support,as ν → ∞, for some bilinear differential operators C j (not depending on f, g and ν).(The assumption of compact support can be relaxed, cf.[9].) We can thus define f * g as the formal power seriesInterpreting ν as th...