ИСТИНА

We present our analysis of the decay constants of pseudoscalar and vector beauty mesons and emphasize that in the bottom-quark sector, two specifoc features of the sum-rule results arise: (i) For the input values of the bottom-quark mass in the $\overline{\rm MS}$ scheme $m_b(m_b)\simeq$ 4.18 GeV, the sum rule estimate for $f_B$ lies in the range 210-220 MeV, i.e. is substantially higher than the recent results from lattice QCD $f_B\simeq 190$ MeV. Requiring that QCD sum rules reproduce the results from lattice QCD for $f_B$ leads to a substantially higher value of the mass $m_b(m_b)=4.247$ GeV. (ii) Whereas the decay constants of charmed mesons, $f_D, f_{D_s}, f_{D^*}$ and $f_{D_s^*}$, obtained from QCD sum rules turned out to be practically independent of the specific choice of the scale $\mu$, in the beauty sector the situation is different: the results for the decay constants, and particularly for the ratio $f_{B^*}/f_B$ turns out to be sensitive to the precise scale-setting.