标题： 多路交汇条件：小册子与网络 显示英文标题

标题： Multiway Junction Conditions: Booklets and Webs

摘要： junction 条件在构建新的引力解中起着至关重要的作用。本文中，我们推导了沿公共界面粘贴任意数量时空的 junction 条件。我们发展了一种反向延展的几何技术，并在界面处提供了几何量的精确定义。这导致了多路 junction 条件的几何推导。作为交叉验证，我们独立重新推导了包括爱因斯坦引力和标量引力在内的特定引力模型的作用量的 junction 条件。我们证明了 junction 条件在框架变换下是不变的，并且对于类空和类时界面，junction 条件的形式相同。 显示英文摘要

摘要： Junction conditions play a crucial role in constructing new gravity solutions. In this paper, we derive the junction condition for gluing together an arbitrary number of spacetimes along a common interface. We develop a geometric technique of reverse extension and provide precise definitions of geometric quantities at the interface. This leads to a geometric derivation of the multiway junction condition. As a cross-check, we independently re-derive the junction condition by varying the action of some specific gravitational models including both Einstein gravity and dilaton gravity. We demonstrate that the junction condition is invariant under a change of frames, and the form of the junction condition is the same for both spacelike and timelike interfaces.