2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53495We show that the Hamiltonian $ h= H_{QED}+H_2$, where $H_{QED}$ is the spinor QED Hamiltonian and $H_2$ is the positive transversal photon mass term, is unbounded from below if the electromagnetic coupling constant $e^2$ is small enough, $e^2<e^2_0 $, and the transversal photon squared mass parameter $M^2$ is not too large: $0\leq M^2<e^2l^2c$, here, $l$ is the cut-off parameter, and $c$ and $e^2_0$, positive constants which do not depend on any parameters.14pages, latexHigh Energy Physics - Theorytext