  The characterization of helical states can be performed by checking the
existence of the re-entrant behaviour, which appears as a dip in the
conductance probed in nanowires (NWs) with strong spin-orbit coupling (SOC) and
under perpendicular magnetic field. On the other hand, the experiment described
in Ref. 1 observed the re-entrant behaviour in the absence of a magnetic field,
which was explained through spin-flipping two-particle backscattering. We
theoretically show that the observation of the re-entrant behaviour is due to a
multi-channel scattering mechanism, which causes a reduction of the
transmission when an effective attractive potential and coupling between
different channels are present. Both ingredients are provided by the SOC in the
transport properties of NWs.
