Decoupling Dark Energy from Matter
  We examine the embedding of dark energy in high energy models based upon
supergravity and extend the usual phenomenological setting comprising an
observable sector and a hidden supersymmetry breaking sector by including a
third sector leading to the acceleration of the expansion of the universe. We
find that gravitational constraints on the non-existence of a fifth force
naturally imply that the dark energy sector must possess an approximate shift
symmetry. When exact, the shift symmetry provides an example of a dark energy
sector with a runaway potential and a nearly massless dark energy field whose
coupling to matter is very weak, contrary to the usual lore that dark energy
fields must couple strongly to matter and lead to gravitational
inconsistencies. Moreover, the shape of the potential is stable under one-loop
radiative corrections. When the shift symmetry is slightly broken by higher
order terms in the Kahler potential, the coupling to matter remains small.
However, the cosmological dynamics are largely affected by the shift symmetry
breaking operators leading to the appearance of a minimum of the scalar
potential such that dark energy behaves like an effective cosmological constant
from very early on in the history of the universe.
