Dark energy, Dirac's scalar field and the cosmological constant problem
  The solutions of the field equations of the conformal theory of gravitation with Dirac scalar field in Weyl-Cartan spacetime in very early universe are obtained. In this theory dark energy (describing by an effective cosmological constant) is a function of the Dirac scalar field $\beta$. These solutions describe the exponential decreasing of $\beta$ at the first exponential stage of inflation. One of these solutions has a limit to a constant value of the dark energy at large time that can give a way to solving the fundamental cosmological constant problem as a consequence of the fields dynamics in the early universe. 
O. V. Babourova, B. N. Frolov
gr-qc astro-ph.CO hep-th