论文标题
$ b_c \ to j/ψ$形式的新总和规则
New Sum Rules for the $B_c \to J/ψ$ Form Factors
论文作者
论文摘要
我们通过$ b_c \ to j/ψ\，\ ell \barν_\ ell $ emmeptonic转换的形式的新总和规则，采用了真空 - $ j/ψ$ - 中间的$ j/ψ$ - $ b_c $ - 互惠函数，$ j/ψ$ - 中间和$ b \ to c $ beforments。在重夸克极限和类似太空的动量转移到弱电流下，本地运算符产品的扩展对于此相关函数有效。结果，在领先的功率上，非扰动输入降低为$ b_c $梅森的衰减常数。此外，在$ j/ψ$通道中应用HADRONIC分散关系时，我们发现$ J/ψ$的非呈现OPE光谱密度仅在$ \ MATHCAL {O}（O}（O}（α_S）$）中出现。我们计算相关运动学状态中的密度。然后从新的总规则中计算出$ b_c \ to j/ψ$表符号。
We derive new sum rules for the form factors of the $B_c\to J/ψ\, \ell \barν_\ell$ semileptonic transitions, employing the vacuum-to-$B_c$ correlation function of the $J/ψ$-interpolating and $b\to c$ weak currents. In the heavy quark limit and at a space-like momentum transfer to the weak current, a local operator-product expansion is valid for this correlation function. As a result, in the leading power, the non-perturbative input is reduced to the decay constant of $B_c$ meson. Furthermore, applying hadronic dispersion relation in the $J/ψ$ channel, we find that a non-vanishing OPE spectral density in the duality interval of $J/ψ$ emerges only at $\mathcal{O}(α_s)$. We calculate this density in the relevant kinematic regime. The $B_c\to J/ψ$ form factors at space-like momentum transfer are then calculated from the new sum rules.
