D*D pi and B*B pi couplings in QCD.
D*D pi and B*B pi couplings in QCD.
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DOI：
10.1103/physrevd.51.6177
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发表时间：
1994-10
期刊：
影响因子：
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通讯作者：
V. Belyaev;V. Braun;A. Khodjamirian;R. Ruckl
中科院分区：
文献类型：
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作者：
V. Belyaev;V. Braun;A. Khodjamirian;R. Ruckl
我们在光锥上用QCD求和规则计算了D*Dπ和B*Bπ耦合。在这种方法中，大距离动力学被纳入一组π波函数。我们考虑两粒子和三粒子波函数的扭曲2，3和4。耦合常数的结果值为gD*Dπ=12.5±1和gB*Bπ=29±3。由此我们预测了部分宽度Γ（D*+→ D_0 π+）=32±5 keV。我们还讨论了软π极限的总和规则，这是等价的外部轴向场的方法在早期的计算。此外，利用g B *Bπ和g D *Dπ，比较了B→π和D→π半轻子形状因子的极优势模型和在相同的光锥求和规则框架下直接计算这些形状因子的结果.
We calculate the D*Dπ and B*Bπ couplings using QCD sum rules on the light cone. In this approach, the large-distance dynamics is incorporated in a set of pion wave functions. We take into account two-particle and three-particle wave functions of twist 2, 3, and 4. The resulting values of the coupling constants are gD*Dπ=12.5±1 and gB*Bπ=29±3. From this we predict the partial width Γ(D*+→D0π+)=32±5 keV. We also discuss the soft-pion limit of the sum rules which is equivalent to the external axial field approach employed in earlier calculations. Furthermore, using gB*Bπ and gD*Dπ the pole dominance model for the B→π and D→π semileptonic form factors is compared with the direct calculation of these form factors in the same framework of ligh-cone sum rules.