Two-Measure Electroweak Standard Model. Some aspects of cosmological evolution and vacuum stability (2501.15623v3)

Abstract: In the FLRW universe, the scalar field \phi(t) obtained by cosmological averaging of the local Higgs field H(x) is considered as a classical field for which the SM quantization procedure is meaningless. When applying the Two-Measure theory (TMT) to study cosmology, the ratio \zeta of the measure densities is a scalar function, which: enters into all equations of motion. Through the constraint, $\zeta$ is defined as a function of \phi(t). During cosmological evolution, \zeta(\phi) changes from \zeta\approx 0 at the inflationary stage to \zeta=1 at the approaching vacuum stage. Each stage of the classical cosmological background is determined by the set {\phi(t), {\rm curvature}, \zeta(\phi(t))}. The Two-Measure SM (TMSM) is realized in the context of cosmology as a set of cosmologically modified copies of the GWS model. Each of the copies exists as a local quantum field theory defined on the classical cosmological background at the appropriate stage of its evolution. This basic idea is studied in detail for the stage of slow-roll inflation and for the stage of approaching vacuum. Due to the presence of \zeta(\phi(t)) in all equations of motion, all TMSM coupling constants turn out to be running (classical) TMT-effective parameters. During cosmological evolution, changing these parameters yields new results: the classical running TMT-effective Higgs selfcoupling increases from \lambda\sim 10^{-11} (which ensures consistency with Planck's CMB data at \xi=\frac{1}{6}) to \lambda\sim 0.1 near vacuum; the mass term in the Higgs potential changes sign from positive to negative, providing standard SSB; the classical running gauge and Yukawa coupling constants change by several orders of magnitude; the GWS theory is reproduced so that the fermion mass hierarchy is obtained quite naturally. 1-loop quantum corrections preserves the slow-roll inflation and does not violate the vacuum stability.