Using the approach based on conformal symmetry we calculate the two-loop coefficient function for the vector flavor-nonsinglet contribution to deeply-virtual Compton scattering (DVCS). The analytic expression for the coefficient function in momentum fraction space is presented in the $$ \overline{\mathrm{MS}} $$ scheme. The corresponding next-to-next-to-leading order correction to the Compton form factor ℋ for a simple model of the generalized parton distribution appears to be rather large: a factor two smaller than the next-to-leading order correction, approximately ∼ 10% of the tree level result in the bulk of the kinematic range, for Q2 = 4 GeV2.

中文翻译：

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DVCS 的双环系数函数：矢量贡献

使用基于共形对称的方法，我们计算向量风味非单波对深度虚拟康普顿散射 (DVCS) 的贡献的双环系数函数。$$ \overline{\mathrm{MS}} $$ 方案中给出了动量分数空间中系数函数的解析表达式。对于广义部分分布的简单模型，对应于康普顿形状因子 ℋ 的紧邻顺序校正似乎相当大：比紧邻顺序校正小 2 的因子，大约为 ∼对于 Q2 = 4 GeV2，10% 的树级别导致大部分运动学范围。