We describe an efficient construction of a canonical noncommutative deformation of the algebraic functions on the moduli spaces of flat connections on a Riemann surface. The resulting algebra is a variant of the quantum moduli algebra introduced by Alekseev, Grosse, and Schomerus and Buffenoir and Roche. We construct a natural trace functional on this algebra and show that it is related to the canonical trace in the formal index theory of Fedosov and Nest and Tsygan via Verlinde's formula. © 2002 Elsevier Science (USA) Key Words: formal deformations; quantum groups; moduli spaces.
Contents.0. Introduction. • the theory of star products or formal deformations of symplectic manifolds, more specifically, the index theorem of Fedosov and Nest and Tsygan (F-NT) [14,19,29].Our first result is a greatly simplified, invariant construction of the quantum moduli algebra. We fix a generic conjugacy class s. The quantum moduli algebra is a canonically defined noncommutative algebra A q , which is finitely generated over a subring D(q) of rational functions in q. The main focus of the present work is shown in the following commuting diagram:We are searching for a natural module K defined over D(q), a trace functional Tr q and a map ev which complete the diagram. In other words, we seek to lift the canonical trace from the infinitesimal world to the global q world.A natural solution to this lifting problem seems to be setting K to be D(q) and ev: D(q) Q CQ(R to be the Laurent expansion at q=1. Surprisingly, cyclic functionals on A Our results are subject to various restrictions and assumption which we have omitted in the discussion so far for the sake of clarity. These will be discussed below and in the main body of the paper.Contents of the paper. In Section 1 we recall the volume formula of Witten and Verlinde's formula. We compute the asymptotics of the q-volume series that we introduce by analogy. In Section 2 we recall the