Normalized boundary triplet for a sum of tensor products of operators

The boundary triplet approach is applied to the construction of self-adjoint extensions of the operator having the form S := A ⊗ IT + IH ⊗ T where the operator A is symmetric and the operator T is self-adjoint. A normalized boundary triplet is constructed, and formulas for the γ-field and the Weyl function are obtained. Applications to Schrödinger and Dirac operators in 1D are given.