论文标题
关于大键/大爆炸中扰动互动图片的分解，或者暂时的orbifolds上扰动弦振幅的真正原因
On the breakdown of the perturbative interaction picture in Big Crunch/Big Bang or the true reason why perturbative string amplitudes on temporal orbifolds diverge
论文作者
论文摘要
我们讨论在某些背景下具有空间样的奇异性但渐近平坦的扰动粒子范式如何失败，这应该接受S-Matrix。 Feynman方法取决于互动图。这种方法意味着我们可以将相互作用解释为粒子的交换。粒子是拉格朗日二次部分的模式。在某些具有太空奇异性的背景下，哈密顿的相互作用是很好的定义，但是不存在通过奇异性和扰动$ s $矩阵的进化操作员的扰动扩展。另一方面，依靠MinisuperSpace近似值，我们认为确实存在非扰动进化算子。扰动扩展的完整分解解释了为什么至少在树级别在树级上，弦理论中协变形式的扰动计算。
We discuss how the perturbative particle paradigm fails in certain background with space-like singularity but asymptotically flat which should admit a S-matrix. The Feynman approach relies on the interaction picture. This approach means that we can interpret interactions as exchanges of particles. Particles are the modes of the quadratic part of the Lagrangian. In certain backgrounds with space-like singularity the interaction Hamiltonian is well defined but the perturbative expansion of the evolution operator through the singularity and the perturbative $S$ matrix do not exist. On the other hand, relying on minisuperspace approximation we argue that the non perturbative evolution operator does exist. The complete breakdown of the perturbative expansion explains why the perturbative computations in the covariant formalism in string theory in temporal orbifold fail, at least at the tree level.
