Fine-structure constant constraints on late-time dark energy transitions
  We use recent astrophysical and local tests of the stability of the
fine-structure constant, $\alpha$, to constrain a particular phenomenological
but physically motivated class of models in which the dark energy equation of
state can undergo a rapid transition at low redshifts, perhaps associated with
the onset of the acceleration phase. We set constraints on the phenomenological
parameters describing such possible transitions, in particular improving
previous constraints (which used only cosmological data) on the present-day
value of the dark energy equation of state in these models. We specifically
quantify how these constraints are improved by the addition of the $\alpha$
measurements. We find no evidence for a transition associated with the onset of
acceleration. In this model the $\alpha$ measurements lead to a bound on Weak
Equivalence Principle violations of $\eta<4\times10^{-15}$ (at $68.3\%$
confidence level), improving on the recent MICROSCOPE bound by about a factor
of three.
