标题： 量子弦宇宙学中的边界条件 显示英文标题

标题： Boundary Conditions in Quantum String Cosmology

摘要： 我们详细讨论了如何在量子弦宇宙学中一致地施加边界条件。由于在量子引力中不存在经典的时标参数，因此这些条件必须相对于内在变量来施加。通过从不同的树级弦有效作用量构造最小超空间模型的波包，我们特别解释了“大爆炸前”和“大爆炸后”分支之间的转变意义。这导致了一个与先前考虑不同的场景。 显示英文摘要

摘要： We discuss in detail how to consistently impose boundary conditions in quantum string cosmology. Since a classical time parameter is absent in quantum gravity, such conditions must be imposed with respect to intrinsic variables. Constructing wave packets for minisuperspace models from different tree-level string effective actions, we explain in particular the meaning of a transition between ``pre-big-bang" and ``post-big-bang" branches. This leads to a scenario different from previous considerations.