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

Abstract

We compute the vector meson decay constants fD* (s) from the simulation of twisted mass QCD on the lattice with Nf = 2 dynamical quarks. When combining these values with the pseudoscalar D (s)-meson decay constants, we were able (i) to show that the heavy quark spin symmetry breaking effects with the charm quark are large, fD* s /fDs = 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 ±10MeV, and fD* s = 311 ?9MeV, 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(B0 → D+π-) quoted by PDG, and find B(B0 → D+π-) = (7.8 ±1.4) ±10-7. Alternatively, by using the ratios discussed in this paper, we obtain B(B0 → D+π -) = (8.3 ±1.0 ±0.8) ×10-7.