Cosmological models with Gurzadyan-Xue dark energy
  The formula for dark energy density derived by Gurzadyan and Xue provides a value of density parameter of dark energy in remarkable agreement with current cosmological datasets, unlike numerous phenomenological dark energy scenarios where the corresponding value is postulated. This formula suggests the possibility of variation of physical constants such as the speed of light and the gravitational constant. Considering several cosmological models based on that formula and deriving the cosmological equations for each case, we show that, in all models source terms appear in the continuity equation. So, one one hand, GX models make up a rich set covering a lot of currently proposed models of dark energy, on the other hand, they reveal hidden symmetries, with a particular role of the separatrix $\Omega_m=2/3$, and link with the issue of the content of physical constants. 
G. V. Vereshchagin and G. Yegorian