标题： 2+1维薄壳虫洞的内腔曲线 显示英文标题

标题： Hypocycloidal throat for 2+1-dimensional thin-shell wormholes

摘要： 最近我们证明了对于$2+1-$维的薄壳虫洞，非圆形的喉部可能在能量条件得到满足的意义上导致物理虫洞。 同样地，本文中我们考虑嵌入在极坐标下的$2+1-$维平直时空中的角度依赖的喉部几何结构。 结果显示，一个通用且自然的喉部几何结构由一个内摆线显著地提供。 也就是说，两个平直的$2+1-$维通过一个内摆线粘合在一起。 每个内摆线所需的能量随着大圆内部滚轮圆的频率增加而增加。 显示英文摘要

摘要： Recently we have shown that for $2+1-$dimensional thin-shell wormholes a non-circular throat may lead to a physical wormhole in the sense that the energy conditions are satisfied. By the same token, herein we consider angular dependent throat geometry embedded in a $2+1-$dimensional flat spacetime in polar coordinates. It is shown that a generic, natural example of throat geometry is provided remarkably by a hypocycloid. That is, two flat $2+1-$dimensions are glued together along a hypocycloid. The energy required in each hypocycloid increases with the frequency of the roller circle inside the large one.