Hiatus perturbation for a singular Schr\"odinger operator with an interaction supported by a curve in \mathbb{R}^3

We consider Schr\"odinger operators in $L^2(\mathbb{R}^3)$ with a singular interaction supported by a finite curve $\Gamma$. We present a proper definition of the operators and study their properties, in particular, we show that the discrete spectrum can be empty if $\Gamma$ is short enough. If it is not the case, we investigate properties of the eigenvalues in the situation when the curve has a hiatus of length $2\epsilon$. We derive an asymptotic expansion with the leading term which a multiple of $\epsilon \ln\epsilon$.