On a physical description and origin of the cosmological constant
  In this paper we use and extend the results present in \cite{1,2,3,4} and in
particular in \cite{4} to obtain a statistical description of the cosmological
constant in a cosmological de Sitter universe in terms of massless excitations
with Planckian effects. First of all, we show that at a classical level, the
cosmological constant $\Lambda>0$ can be obtained only for $T\rightarrow 0$.
Similarly to the black hole case, when quantum effects are taken into account,
a representation for $\Lambda$ is possible in terms of massless excitations,
provided that quantum corrections to the Misner-Sharp mass are considered.
Moreover, thanks to quantum fluctuations, an effective cosmological constant
arises depending on the physical scale under consideration, thus representing a
possible solution to the cosmological constant problem without introducing a
quintessence field. The smalness of the actual value for $\Lambda$ can be due
to the existence of a quantum decoherence scale above the Planck length such
that the spacetime evolves as a pure de Sitter universe with a small averaged
cosmological constant frozen in the lowest energy state.
