Real and imaginary energy gaps: a comparison between single excitation Superradiance and Superconductivity and robustness to disorderNahum C. Chávez, Francesco Mattiotti, J.A. Méndez-Bermúdez, Fausto Borgonovi and G. Luca CelardoEur. Phys. J. B, 92 7 (2019) 144DOI: https://doi.org/10.1140/epjb/e2019-100016-3