In fact, theoretical calculations were performed to precisely determine the energy of chiral molecules compared to their corresponding mirror-images. Calculations for the individual enantiomers resulted in the astonishing consequence that the energy of a given enantiomer is indeed non-identical to the energy of its own mirror-image. The obtained differences are called parity non-conserving (PNC) energy differences AEpnc or sometimes parity-violating energy differences (PVEDs), as eye-catching illustrated by the number plate of one of its protagonists (Fig. 5.4). The value of this asymmetry is, of course, extremely small in comparison with the involved Coulomb interaction. The weak part of the binding energy VPNC is - in contrast to the Coulomb interaction - characterized by the following parameters.
1. The Fermi coupling constant determines the force of the weak interaction, which is consequently much smaller than the Coulomb interaction VCoul determined by charges of interacting particles. The weakness of the weak force is based on the W and Z bosons that are relatively heavy or - which means the same - that the effective reach of the weak nuclear current is extremely small.
2. The strength of the weak interaction is no more in inverse proportion to the distance of particles such as we know it from the Coulomb interaction, but active on extremely small distances, smaller than the radius of a proton.
3. The characteristic of the weak part of the binding energy VPNC is that it bears the spatial asymmetry in mind. This spatial asymmetry is described and can be calculated by an interaction between spin and momentum of the interacting particles
called helicity. The helicity itself is considered a pseudo-scalar value, since its sign changes by mirror-reflection of the coordinate system.
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