  I introduce (Extended) Proca-Nuevo, a non-linear theory of a massive spin-1
field enjoying a non-linearly realized constraint. I will provide a
covariantization scheme that allows for consistent, ghost-free cosmological
solutions, describing the correct number of dynamical variables in the presence
of perfect fluid matter. I will finally exhibit explicit hot Big Bang solutions
featuring a late-time self-accelerating epoch, where all the stability and
subluminality conditions are satisfied and where gravitational waves behave
precisely as in General Relativity.

General Relativity and Quantum Cosmology;High Energy Physics - Theory