Vacuum Crystallography (VCV48) Neutrino Helicity Conversion in the Oh Lattice and Sidereal Modulation of the M87 Neutrino Flux.

The coupling of a fermionic field (neutrino) to the deformation tensor of the vac- uum with octahedral symmetry Oh (order 48) is derived using the tetrad formalism. It is shown that helicity conversion vanishes exactly in the three high-symmetry di- rections of the group (⟨100⟩, ⟨110⟩, ⟨111⟩). The exact polynomial factorization of the function GT (x) that controls the helicity mixing amplitude is obtained, and its global maximum is determined in the direction (0.28329927, 0.28329927, 0.91623307) of the crystallographic frame, with value Gmax T = 0.065706. The maximum ampli- tude of sidereal modulation of the M87 neutrino flux is calculated: Aν ≤ 2.45%, with a typical value Aν ≈ 2.40% for generic crystal orientations. The falsifiability criteria of the model in the neutrino channel are presented.