Bicrossproduct Structure of Affine Quantum Groups

We show that the affine quantum group $U_q(\hat{sl_2})$ is isomorphic to a bicrossproduct central extension $C Z{}_\chi\cross U_q(Lsl_2)$ of the quantum loop group $U_q(Lsl_2)$ by a quantum cocycle $\chi$, which we construct. We prove the same result for $U_q(\hat{g})$ in R-matrix form.