A Symmetry-Protected Scalar Vacuum Framework: Semi-Emergent Gravity and Neutrino-Triggered Early Dark Energy

We present a scalar-tensor effective field theory in which gravitational dynamics, particle masses, and dark energy emerge from the vacuum structure of a symmetry-protected pseudo-Goldstone boson. This framework, the Symmetry-Protected Scalar Vacuum (SPSV), demonstrates how the transition of neutrinos to a non-relativistic regime triggers a transient Early Dark Energy (EDE) phase, alleviating the H0 and sigma8 tensions. The model predicts a time-dependent gravitational coupling and specific signatures for future CMB and LHC observations.