  Semiconductor nanowires with strong spin-orbit coupling and proximity-induced
s-wave superconductivity in an external magnetic field have been the most
promising settings for approaches towards experimental evidence of topological
Majorana zero-modes. We investigate the effect of tilting the magnetic field
relative to the spin-orbit coupling direction in a simple continuum model and
provide an analytical derivation of the critical angle, at which the
topological states disappear. We also obtain the differential conductance
characteristic of a junction with a normal wire for different tilting angles
and propose the qualitative change of the dependence of the zero-energy
differential conductance on the tunnel barrier strength at the critical angle
as a new criterion for establishing the topological nature of the observed
signal.
