QCD FACTOR-A(1) AND FACTOR-A(2) BEYOND LEADING LOGARITHMS VERSUS FACTORIZATION IN NONLEPTONIC HEAVY MESON DECAYS

We calculate the QCD factors a(1) and a(2), entering the tests of fact orization in non-leptonic heavy meson decays, beyond the leading logar ithmic approximation in three renormalization schemes (NDR, HV, DRED). We investigate their mu dependence and the renormalization scheme dep endence. We point out that a(1) for B-decays depends very weakly on La mbda(MS), mu and the choice of the renormalization scheme. For Lambda( MS)/((5)) = 225 +/- 85 MeV and 4 GeV less than or equal to mu less tha n or equal to 8 GeV we find a(1) = 1.01 +/- 0.02 in accordance with ph enomenology. The lambda(MS), mu and scheme dependences of a(2) are on the other hand sizable. Interestingly, for the NDR scheme we find a(2) (NDR) = 0.20 +/- 0.05, in the ball park of recent phenomenological res ults and substantially larger than leading order estimates. However a( 2)(HV) = 0.16 +/- 0.05 and a(2)(DRED) = 0.15 +/- 0.05. Implications of these findings for the tests of factorization in B-decays and D-decay s are critically discussed.