Although commonly called ``trion line'', the low-energy line observed in the absorption spectrum of doped quantum wells, is not due to a bound 3-body object, the trion. In fact, it comes from a many-body object, spectrally wide by nature, made of one composite exciton and a large number of electrons, interacting through both Coulomb and Pauli scatterings, i.e., Coulomb interaction without carriers exchange, and carriers exchange without Coulomb process. This understanding is experimentally supported by the highly asymmetrical shape of the circular dichroism spectrum measured with a spin-polarized electron gas: this spectrum shows a sharp edge at low energy and a long tail a high energy, which are well explained by a singular many-body effect, while they completely rule out an explanation in terms of trion, either free or bound.