标题： 共形QCD中的双光子过程：领头 twist 算符的后裔的重求和 显示英文标题

标题： Two-photon processes in conformal QCD: Resummation of the descendants of leading-twist operators

摘要： 利用共形场论的一些技巧，我们得到了由 twist-lead 算符及其导出子（通过添加全导数得到）对 QCD 中两个电磁流的算符积展开（OPE）的贡献的闭合表达式。 我们的表达式重新求和了所有 twist 的贡献，并且在微扰理论的所有阶次中均成立，误差仅为与 QCD 的$\beta$-函数成正比的修正。 在树级近似和四阶 twist 精度下，我们的结果与先前通过不同方法推导出的结果一致。 这些结果可以直接应用于深虚康普顿散射以及，例如，两介子的$\gamma\gamma^\ast$湮没。 作为副产品，我们得到了两个标量流 OPE 的一个简单表示形式，这在应用中非常方便。 显示英文摘要

摘要： Using some techniques of conformal field theories, we find a closed expression for the contribution of leading twist operators and their descendants, obtained by adding total derivatives, to the operator product expansion (OPE) of two electromagnetic currents in QCD. Our expression resums contributions of all twists and to all orders in perturbation theory up to corrections proportional to the QCD $\beta$-function. At tree level and to twist-four accuracy, our result agrees with the expression derived earlier by a different method. The results are directly applicable to deeply-virtual Compton scattering and, e.g., $\gamma\gamma^\ast$ annihilation in two mesons. As a byproduct, we derive a simple representation for the OPE of two scalar currents that is convenient for applications.