标题： 大弦模与非奇异先大爆炸宇宙学 显示英文标题

标题： Massive string modes and non-singular pre-big-bang cosmology

摘要： 关于低能弦有效作用量的微扰 $\alpha '$ 修正最近被发现可能对最低阶大爆炸之前的解的奇异性具有正则化效应。然而，由于方案依赖性模糊性，在任何有限阶的弦常数 $\alpha '$ 的微扰展开中都无法确定它们是否真正起到了正则化的作用。 从物理上讲，这些修正主要由前几个高能弦态的积分所主导。相反，非常高的弦模可以具有非微扰的正则化效应，这种效应取决于 $\alpha '$，并且基本上源于在一个具有哈勃常数 $H$ 的引力场中，它们以有效的霍金温度 $T=H/(2\pi)$ 被产生，如果这个温度超过了哈德森温度，则会出现无限的产生率。 我们讨论了这种非微扰正则化机制的技术和概念上的困难。 显示英文摘要

摘要： Perturbative $\alpha '$ corrections to the low energy string effective action have been recently found to have a potentially regularizing effect on the singularity of the lowest order pre-big-bang solutions. Whether they actually regularize it, however, cannot be determined working at any finite order in a perturbative expansion in powers of the string constant $\alpha '$, because of scheme dependence ambiguities. Physically, these corrections are dominated by the integration over the first few massive string states. Very massive string modes, instead, can have a regularizing effect which is non-perturbative in $\alpha '$ and which basically comes from the fact that in a gravitational field with Hubble constant $H$ they are produced with an effective Hawking temperature $T=H/(2\pi)$, and an infinite production rate would occur if this temperature exceeded the Hagedorn temperature. We discuss technical and conceptual difficulties of this non-perturbative regularization mechanism.