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

A bstract We compute the vector meson decay constants f_D_(s)* from the simulation of twisted mass QCD on the lattice with N f = 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, f_Dₛ*/f_Dₛ = 1.26(3) , and (ii) to check the factorization approximation in a few specific B -meson non-leptonic decay modes. Besides our main results, f_D* = 278± 13± 10\,MeV , and f_Dₛ* = 311± 9\,MeV , other phenomenologically interesting results of this paper are: f_Dₛ*/f_D* = 1.16± 0.02± 0.06 , f_Dₛ*/f_D* = 1.46± 0.05± 0.06 , and f_Dₛ/f_D* = 0.89± 0.02± 0.03 . Finally, we correct the value for B ( B 0 → D + π − ) quoted by PDG, and find B ( B 0 → D + π − ) = (7.8 ± 1.4) × 10 −7 . Alternatively, by using the ratios discussed in this paper, we obtain B ( B 0 → D + π − ) = (8.3 ± 1.0 ± 0.8) × 10 −7 .