Kontsevich Deformation Quantization and Flat Connections

In arXiv:math/0105152, the second author used the Kontsevich deformation quantization technique to define a natural connection omega_n on the compactified configuration spaces of n points on the upper half-plane. This connection takes values in the Lie algebra of derivations of the free Lie algebra with n generators. In this paper, we show that omega_n is flat. The configuration space contains a boundary stratum at infinity which coincides with the (compactified) configuration space of n points on the complex plane. When restricted to this stratum, omega_n gives rise to a flat connection omega_n^infty. We show that the parallel transport Phi defined by omega_3^infty between configuration 1(23) and (12)3 verifies axioms of an associator. We conjecture that omega_n^infty takes values in the Lie algebra of infinitesimal braids. This conjecture implies that Phi is an even Drinfeld associator defining a new explicit solution of associator axioms. A proof of this conjecture has recently appeared in arXiv:0905.178