Spectral Transition for Dirac Operators with Electrostatic δ -Shell Potentials Supported on the Straight Line.

In this note the two dimensional Dirac operator A η with an electrostatic δ -shell interaction of strength η ∈ R supported on a straight line is studied. We observe a spectral transition in the sense that for the critical interaction strengths η = ± 2 the continuous spectrum of A η inside the spectral gap of the free Dirac operator A 0 collapses abruptly to a single point.