Dark matter, dark energy and the time evolution of masses in the
  Universe
  The traditional "explanation" for the observed acceleration of the universe
is the existence of a positive cosmological constant. However, this can hardly
be a truly convincing explanation, as an expanding universe is not expected to
have a static vacuum energy density. So, it must be an approximation. This
reminds us of the so-called fundamental "constants" of nature. Recent and past
measurements of the fine structure constant and of the proton-electron mass
ratio suggest that basic quantities of the standard model, such as the QCD
scale parameter $\Lambda_{QCD}$, might not be conserved in the course of the
cosmological evolution. The masses of the nucleons and of the atomic nuclei
would be time-evolving. This can be consistent with General Relativity provided
the vacuum energy itself is a dynamical quantity. Another framework realizing
this possibility is QHD (Quantum Haplodynamics), a fundamental theory of bound
states. If one assumes that its running couplings unify at the Planck scale and
that such scale changes slowly with cosmic time, the masses of the nucleons and
of the DM particles, including the cosmological term, will evolve with time.
This could explain the dark energy of the universe.
