$q$. For the other parameters, we have fixed the values $h_x=h_z=0.5$ meV for the Zeeman components, $T_c = 1$ meV, and $\mu = 1$ eV for the Fermi energy. In order to obtain $q_0$ which could be experimentally observable, it is necessary to “push” the SO parameter to values such as $ \tilde{\alpha}= 100 \, \,  {\rm meV}.{\text{\normalfont\AA}}$, which are now experimentally available but fall far beyond the domain of validity of the above result Eq. (\[q0\_weak\]).

\[sec:strong\_soc\] Strong spin-orbit coupling
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In the previous section, the self-consistency relation was derived in the case of weak spin-orbit interaction: $\alpha\,p_\text{F} \ll T_c$. This section is devoted to the opposite situation characterized by a strong spin-orbit coupling $\alpha\,p_\text{F} \gg T_c$. After rewriting the normal Hamiltonian of Eq. (\[H\]) in the *helical basis* with diagonalizes it, we derive the self-consistency relation, in the limit of a small $\Delta_0$, but for strong spin-orbit coupling. This allows to plot the $\left(h_x,h_z,T\right)$-phase diagram for various orientations of the Zeeman field and large spin-orbit coupling constants. The limit of strong-spin orbit coupling, typically $ \tilde{\alpha}= 300 \, \,  {\rm meV.A}$, can be achieved in narrow gap semiconductors like InAs or InSb combined with aluminium as superconductor [@krogstrup_epitaxy_2015; 