标题： 二维弦宇宙学中的奇点和退出问题 显示英文标题

标题： Singularity and exit problems in two-dimensional string cosmology

摘要： 一类二维环路修正的标量引力模型展现出宇宙学解，这些解在弦微扰真空与具有渐近平坦度规和线性增长标量场的背景之间进行插值。 对应树级解中的曲率奇异性被抹平了，但未发生分支变化。 因此，即使存在非微扰势，系统也不会被具有恒定标量场的物理上有趣的不动点吸引，弦宇宙学的退出问题依然存在。 显示英文摘要

摘要： A broad class of two-dimensional loop-corrected dilaton gravity models exhibit cosmological solutions that interpolate between the string perturbative vacuum and a background with asymptotically flat metric and linearly growing dilaton. The curvature singularities of the corresponding tree-level solutions are smoothed out, but no branch-change occurs. Thus, even in the presence of a non-perturbative potential, the system is not attracted by physically interesting fixed points with constant dilaton, and the exit problem of string cosmology persists.