herein. In this section, I only summarise those elements which are of interest in the narrow scope of this paper.

Inspection of Figs. \[fig:NuNu\]-\[fig:NuElPos\] reveals that, in order to derive the various weak-interaction scattering amplitudes, one needs to obtain the leptonic currents applicable in the cases of the NC (vertices involving $Z^0$) and of the CC (vertices involving $W^\pm$). The latter are purely $V-A$ in character (‘purely’ implies equal - and opposite in sign - contributions of the vector and axial-vector components, ensuring the left-handedness of the neutrino and the right-handedness of the antineutrino), given for the $l \to \nu_l$ transition by the expression $$\bra{u(\nu_l)} J_\mu \ket{u(l)} = \frac{g}{\sqrt{2}} \bar{u}(\nu_l) \gamma_\mu \frac{1-\gamma_5}{2} u(l) \, \, \, ,$$ where the constant $g$ determines the overall strength of the CC processes. Of course, $u(l)$ is the spinor associated with the lepton $l$ (where $l$ denotes an electron, a muon, or a $\tau$-lepton) and $u(\nu_l)$ is the spinor associated with the corresponding neutrino; in this work, only electrons and electron neutrini are of relevance. The dependence of the spinors on the spin and on the $4$-momentum of the fermions is assumed (but not explicitly given). The normalisation condition of the spinors, associated with 