We propose a new splitting behavior of tree-level string/particle amplitudes for massless scalars, gluons and gravitons. We identify certain subspaces in the space of Mandelstam variables, where the universal Koba-Nielsen factor splits into two parts (each with an off-shell leg). Both open- and closed-string amplitudes with Parke-Taylor factors naturally factorize into two stringy currents, which implies the splitting of bi-adjoint ϕ3 amplitudes and via a simple deformation to unified stringy amplitudes, the splitting of amplitudes in the non-linear sigma model and Yang-Mills-scalar theory; the same splitting holds for scalar amplitudes without color such as the special Galileon. Remarkably, if we impose similar constraints on Lorentz products involving polarizations, gluon and graviton amplitudes in bosonic string and superstring theories also split into two (stringy) currents. A special case of the splitting implies soft theorems, and more generally it extends recently proposed smooth splittings and new factorizations near zeros to all these theories.

中文翻译：

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树级弦和粒子散射幅度的通用分裂


我们提出了无质量标量、胶子和引力子的树级弦/粒子振幅的新分裂行为。我们在曼德尔斯塔姆变量的空间中识别出某些子空间，其中通用科巴-尼尔森因子分为两部分（每个部分都有一个离壳腿）。具有 Parke-Taylor 因子的开弦振幅和闭弦振幅自然地分解为两个弦电流，这意味着双伴随 phi3 振幅的分裂，并且通过简单变形为统一弦振幅，非线性 sigma 中的振幅分裂模型和杨-米尔斯标量理论；同样的分裂也适用于没有颜色的标量振幅，例如特殊的伽利略。值得注意的是，如果我们对涉及极化的洛伦兹积施加类似的约束，玻色弦和超弦理论中的胶子和引力子振幅也会分裂成两个（弦）电流。分裂的一个特殊情况意味着软定理，更一般地说，它将最近提出的平滑分裂和新的接近零的因式分解扩展到所有这些理论。