2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/135185Many manifestly non-Hermitian Hamiltonians (typically, PT-symmetric complex anharmonic oscillators) possess a strictly real, "physical" bound-state spectrum. This means that they are (quasi-)Hermitian with respect to a suitable non-standard metric. The domain D of the existence of this metric is studied here for a nontrivial though still non-numerical four-parametric "benchmark" matrix model.18 pages, 2 figuresQuantum Physicstext