D-meson decay constants and a check of factorization in non-leptonic B-decays

We compute the vector meson decay constants fD*((s)) from the simulation of twisted mass QeD on the lattice with N-f - 2 dynamical quarks. When combining these values with the pseudoscalar D-(s)-meson decay constants, we were able (1) to show that the heavy quark spin symmetry breaking effects with the charm quark are large. fD*(s)/fD(s) = 1.26(3), and (ii) to check the factorization approximation in a few specific B-meson non-leptonic decay modes. Besides our main results, fD* = 278 +/- 13 +/- 10 MeV, and fD*(s) = 311 +/- 9 MeV, other phenomenologically interesting results of this paper are: fD*(s)/fD* = 1.16 +/- 0.02 +/- 0.06, fD*(s)/fD - 1.46 +/- 0.05 +/- 0.06, and fD(s)/fD* - 0.89 +/- 0.02 +/- 0.03. Finally, we correct the value for B(B-0 -> D+pi(-)) quoted by PUG, and find B(B-0 -> D+pi(-)) = (7.8 +/- 1.1) x 10(-7). Alternatively, by using the ratios discussed in this paper, we obtain B(B-0 -> D+pi(-)) - (8.3 +/- 1.0 +/- 0.8) X 10(-7).