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arXiv 2107.08009hep-th
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有效超弦相互作用的单圈矩阵元:$α'$ -扩展圈被积函数

One-loop matrix elements of effective superstring interactions: $α'$-expanding loop integrands

Alex Edison, Max Guillen, Henrik Johansson, Oliver Schlotterer, Fei Teng

摘要:

在弦论的低能有效作用量中,非阿贝尔规范相互作用和超引力被无限高质量维度算符的塔所增强。本文提出了一种新的方法,在I型和II型超弦的树级有效作用量中插入算子$D^{2k} F^n$和$D^{2k} R^n$来构造单圈矩阵元.受ambitwistor弦论的启发,我们的方法是基于模空间积分的前向极限,使用弦树级振幅与两个额外的点,扩展的逆弦张力的幂$α'$。类似于一个循环的ambitwistor计算,中间步骤功能非标准的线性化费曼传播,最终重组到传统的二次传播。与线性传播矩阵元素的循环被积函数服从单值和KLT关系的一个循环版本。我们表达了各种四点和五点的例子,在二次传播和制定一个标准的基础genus-one关联函数,应该使这种重组可能在所有订单$α'$。单圈矩阵元的紫外发散与弦振幅的亏格积分的非分离退化进行了交叉检验。相反,我们的结果可以用来作为一个建设性的方法来确定退化的椭圆多重zeta值和模图形式在任意重量。

英文摘要:

In the low-energy effective action of string theories, non-abelian gauge interactions and supergravity are augmented by infinite towers of higher-mass-dimension operators. We propose a new method to construct one-loop matrix elements with insertions of operators $D^{2k} F^n$ and $D^{2k} R^n$ in the tree-level effective action of type-I and type-II superstrings. Inspired by ambitwistor string theories, our method is based on forward limits of moduli-space integrals using string tree-level amplitudes with two extra points, expanded in powers of the inverse string tension $α'$. Similar to one-loop ambitwistor computations, intermediate steps feature non-standard linearized Feynman propagators which eventually recombine to conventional quadratic propagators. With linearized propagators the loop integrand of the matrix elements obey one-loop versions of the monodromy and KLT relations. We express a variety of four- and five-point examples in terms of quadratic propagators and formulate a criterion on the underlying genus-one correlation functions that should make this recombination possible at all orders in $α'$. The ultraviolet divergences of the one-loop matrix elements are crosschecked against the non-separating degeneration of genus-one integrals in string amplitudes. Conversely, our results can be used as a constructive method to determine degenerations of elliptic multiple zeta values and modular graph forms at arbitrary weight.

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