Renormalizable Quantum Gravity from Chiral Neutrino Masses: A Standard Model Two-Higgs Minimal Extension with Experimental Evidence

Contrary to the conjecture of many, the General Theory of Relativity (GR) and its Einstein field equation -κTμν=Rμν-½gμνR+gμνΛ do not have to be modified to transition from classical to quantum gravity. All that is needed is a quantum understanding of how the gravitational weakness embodied in the Einstein constant κ=8πGN/c4 arises from tiny left-chiral neutrino masses. The single postulate of a two-Higgs minimal extension to the Standard Model of Particle Physics (SM) informed by current empirical neutrino mass data—from which corollaries of gravitational and chiral mass hierarchy equivalence, and a Type-I neutrino mass seesaw, emerge—produces Newton’s GN≈ℏc5Σi4mνiL/Κ4vF2mD4 as a function of the left-chiral neutrino mass sum ΣimνiL, the Fermi vev vF, a Dirac mass seesaw fulcrum mD, and a neutrino mass variance constant Κ. The Newtonian linear approximation reveals renormalizable quantum gravity mediated by a composite of strength-weakening spin 3/2 gravitinos enveloped by neutrino loops, in addition to expected spin 2 gravitons (Figure 2). These gravitino/neutrino composites have masses that tightly align with those of the enigmatic sigma meson (f0(500)) and have all but their scalar polarizations suppressed, suggesting we have had experimental evidence of quantum gravity for more than sixty years without realizing this. The two-Higgs mechanism motivates a proposed experiment using hydride collisions at LHC/FCC to produce and detect evidence of predicted ~PeV right-chiral neutrino masses (Tables 3 and 4) and further test this sigma meson connection. Aside from the minimal two-Higgs SM extension, quantum gravity emerges without any alterations whatsoever to the SM or to GR.