Existence of abelian BPS vortices on surfaces with Neumann boundary conditions
Rene Garcia-Lara
TL;DR
This work addresses the existence and structure of abelian BPS vortices on compact Riemannian surfaces with boundary under Neumann boundary conditions. Using a Taubes equation with Neumann boundary and a regularisation via Green functions, it proves a Bradlow-type condition $N+\frac{M}{2}<\frac{A}{4\pi}$ guaranteeing a unique vortex solution for prescribed interior and boundary zeros, up to gauge. It shows energy and flux quantisation $E=(2N+M)\pi$, $\Phi=(2N+M)\pi$, and that boundary zeros contribute half-vortex amounts. Numerical computations on the disk illustrate both interior and boundary vortices and reveal that the $L^2$ metric on moduli space can depend on boundary data, signaling a departure from the purely local localization observed in closed surfaces or Dirichlet problems.
Abstract
Existence of abelian BPS vortices on a manifold with boundary satisfying Neumann boundary conditions is proved. Numeric solutions are constructed on the Euclidean disk, and the L^2-metric of the moduli space of one vortex located at the interior of a rotationally symmetry disk is studied. The results presented extend previous work of Manton and Zhao on quotients of surfaces that admit a reflection.
