Endpoint eigenfunction restriction estimates in codimension two

We investigate the optimal endpoint $L^2$ restriction estimates of Laplace eigenfunctions on submanifolds of codimension 2 in a smooth closed Riemannian manifold $M$. For every fixed smooth codimension-two submanifold $Σ$, we prove a little-oh improvement $o(λ^{1/2}\sqrt{\logλ})$ on the classical es