## Hiatus perturbation for a singular Schroedinger operator with an interaction supported by a curve in R{sup 3}

We consider Schroedinger operators in L{sup 2}(R{sup 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}.