Long-living carriers in a strong electron-phonon interacting two-dimensional doped semiconductor

Carrier doping by the electric field effect has emerged as an ideal route for monitoring many-body physics in two-dimensional materials where the Fermi level is tuned so that the strength of the interactions can also be scanned. The possibility of systematic doping together with high resolution photoemission has allowed to uncover a genuinely many-body electron spectrum in single-layer MoS2 transition metal dichalcogenide, resolving three clear quasi-particle states, where only one should be expected if the electron-phonon interaction vanished. Here, we combine first-principles and consistent complex plane analytic approaches and bring into light the physical origin of the two gaps and the three quasi-particle bands which are unambiguously present in the photoemission spectrum. One of these states, though being strongly interacting with the accompanying virtual phonon cloud, presents a notably long lifetime which is an appealing property when trying to understand and take advantage of many-body interactions to modulate transport properties.