2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19548Recent energy dispersion measurements in several families of the hole-doped copper oxides have revealed a kink in the energy vs. momentum relation. These have tentatively been identified as due to electron phonon coupling. We invert this data directly to determine the bosonic spectral function; the kink gives rise to a singular function in the phonon energy region.v2: More detailed discussion of the used inversion procedure is addedSuperconductivitytext