Decay constants of heavy-light vector mesons from QCD sum rules
Abstract
We revisit QCD sum rules for the decay constants of heavy-light mesons. In the sum rules for the vector mesons B^*_(s) and D^*_(s) we improve the accuracy of OPE, taking into account the O(alpha_s^2) terms in the perturbative part and calculating the O(alpha_s) corrections to the quark-condensate contribution. With this accuracy, we obtain the ratios of decay constants: f_B^*/f_B=1.02 +0.07 -0.03, f_D^*/f_D=1.20 +0.10 -0.07. The sum rule predictions for the decay constants of pseudoscalar mesons are updated with the results f_B=(207 +17 -9) MeV, f_B_s=(242 +17 -12) MeV, f_D=(201 +12 -13) MeV, f_D_s=(238 +13 -23) MeV. In order to assess the sensitivity of our calculation to the form of the sum rule, we consider alternative versions such as the power moments and Borel sum rules with different weights of the spectral density. We also investigated the heavy quark limit of the sum rules for vector and pseudoscalar mesons, estimating the violations of the heavy-quark spin and flavour symmetry.
Cite
@article{arxiv.1305.5432,
title = {Decay constants of heavy-light vector mesons from QCD sum rules},
author = {Patrick Gelhausen and Alexander Khodjamirian and Alexei A. Pivovarov and Denis Rosenthal},
journal= {arXiv preprint arXiv:1305.5432},
year = {2015}
}
Comments
30 pages, v3: Uncertainties of the ratios of decay constants corrected. Central values and all other results not changed. , v2: Normalization factor in eq.(53) corrected, causing a slight decrease of the recalculated numerical values for f_B^*_s and f_D^*_s; some misprints corrected; version published in journal