The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order...The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order, i.e. sum rules I and II, which are derived from the conventional correlator and the correlator with chiral currents respectively. It is found that these two sum rules are consistent with each other. The sum rules H involves less non-perturbative condensates as that of sum rules I, and in principle, it can be more accurate if we know the dimensionfour gluon condensate well. It is found that fB decreases with the increment of mb, and to compare with the Belle experimental data on fB, both sum rules I and H prefer smaller pole b-quark mass, mb= 4.68 ± 0.07 GeV. By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain fB=172-25^＋23 MeV for sum rules I and fB =214-34^26 MeV for sum rules П.展开更多
基金Supported by Natural Science Foundation Project of CQ CSTC under Grant No.2008BB0298by Natural Science Foundation of China under Grant Nos.10805082 and 11075225by the Fundamental Research Funds for the Central Universities under Grant No.CDJZR101000616
文摘The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order, i.e. sum rules I and II, which are derived from the conventional correlator and the correlator with chiral currents respectively. It is found that these two sum rules are consistent with each other. The sum rules H involves less non-perturbative condensates as that of sum rules I, and in principle, it can be more accurate if we know the dimensionfour gluon condensate well. It is found that fB decreases with the increment of mb, and to compare with the Belle experimental data on fB, both sum rules I and H prefer smaller pole b-quark mass, mb= 4.68 ± 0.07 GeV. By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain fB=172-25^＋23 MeV for sum rules I and fB =214-34^26 MeV for sum rules П.
