标题： 散射截面和全局单极子的稳定性 显示英文标题

标题： Scattering Cross Section and Stability of Global Monopoles

摘要： 我们研究标量波在全局单极子背景上的散射。由于这种拓扑缺陷中的标量波算子不是本质自伴的，其解在原点处未指定边界条件之前无法唯一确定。如我们所展示的，这个边界条件会在微分散射截面中表现出来，并可以通过测量反向散射波的振幅来推断。我们进一步证明，时空在标量扰动下的稳定性也依赖于所选择的边界条件。特别是，我们确定了一类这样的边界条件，它显著影响微分散射截面而不引入不稳定性。 显示英文摘要

摘要： We study the scattering of scalar waves propagating on the global monopole background. Since the scalar wave operator in this topological defect is not essentially self-adjoint, its solutions are not uniquely determined until a boundary condition at the origin is specified. As we show, this boundary condition manifests itself in the differential cross section and can be inferred by measuring the amplitude of the backscattered wave. We further demonstrate that whether or not the spacetime is stable under scalar perturbations also relies on the chosen boundary condition. In particular, we identify a class of such boundary conditions which significantly affects the differential cross section without introducing an instability.