  We argue that Nash theory, a quadratic theory of Gravity, can describe a
late-time cosmic acceleration without any exotic matter or cosmological
constant. The observational viability of an exact cosmological solution of Nash
theory is adjudged using a Markov chain Monte Carlo simulation and JLA+OHD+BAO
data sets. Departures from standard {\Lambda}CDM cosmology are noted and
analyzed. We prove that the Nash vacuum dynamics is equivalent to the dynamics
of an Einstein vacuum plus a self-interacting Higgs scalar field, only if a
mild evolution of the Higgs Vacuum Expectation Value is allowed. This leads to
variations in the mass scales of fundamental particles and the fine structure
constant. The variations are found to fit nicely with the analysis of molecular
absorption spectra from a series of Quasars.
