ANALYSIS OF D→ππ BEYOND NAIVE FACTORIZATION.

We analyze the D→ππ decay channels at the leading order, αs corrections with the QCD factorization and the soft-gluon corrections with the light cone QCD sum rule. Comparing with the experimental result, the calculations of the D0→π+π- and D+→π+π0 decay are much better under the consideration of the contributions of factorization parts, αs corrections and soft-gluon effects. However, the calculation result is one order less than the experimental result in D0→π0π0 decay. It may have large effects of final state interaction in the decay channel. [ABSTRACT FROM AUTHOR]