An -adic valuation property of universal R-matrices

We prove that if is a quasitriangular QUE algebra with universal R-matrix R, and is the quantized function algebra sitting inside , then log(R) belongs to the tensor square . This gives another proof of the results of Gavarini and Halbout, saying that R normalizes and therefore induces a braiding of the formal group G* (in the sense of Weinstein and Xu, or Reshetikhin).