标题： 非均匀弦宇宙学 显示英文标题

标题： Inhomogeneous String Cosmologies

摘要： 我们给出了包含膨胀子和轴子场的低能弦理论的精确非均匀和各向异性宇宙学解。 时空度规具有圆柱对称性。 这些解描述了从初始曲率奇点开始不断膨胀的宇宙，并且包含已知的均匀解作为子情况。 在初始奇点附近的解的渐近形式具有空间变化的Kasner类似形式。 发现非均匀的轴子和膨胀子场在大于粒子视界尺度上准均匀地演化。 当非均匀性进入视界时，它们作为非线性波振荡，并且非均匀性减弱。 当非均匀性较小时，它们表现得像均匀宇宙的小扰动。 研究了对偶性的表现和解的渐近行为。 显示英文摘要

摘要： We present exact inhomogeneous and anisotropic cosmological solutions of low-energy string theory containing dilaton and axion fields. The spacetime metric possesses cylindrical symmetry. The solutions describe ever-expanding universes with an initial curvature singularity and contain known homogeneous solutions as subcases. The asymptotic form of the solution near the initial singularity has a spatially-varying Kasner-like form. The inhomogeneous axion and dilaton fields are found to evolve quasi-homogeneously on scales larger than the particle horizon. When the inhomogeneities enter the horizon they oscillate as non-linear waves and the inhomogeneities attentuate. When the inhomogeneities are small they behave like small perturbations of homogeneous universes. The manifestation of duality and the asymptotic behaviour of the solutions are investigated.