**
Below is the ascii version of the abstract for 14-86.
The html version should be ready soon.**Pavel Exner and Stepan S. Manko
Spectra of magnetic chain graphs: coupling constant perturbations
(519K, pdf)
ABSTRACT. We analyze spectral properties of a quantum graph in the form of a ring chain with a $\delta$ coupling in the vertices exposed to a homogeneous magnetic field perpendicular to the graph plane. We find the band spectrum in the case when the chain exhibits a translational symmetry and study the discrete spectrum in the gaps resulting from changing a finite number of vertex coupling constants. In particular, we discuss in details some examples such as perturbations of one or two vertices, weak perturbation asymptotics, and a pair of distant perturbations.