Scalar-tensor gravity in an accelerating universe

摘要: We consider scalar-tensor theories of gravity in an accelerating universe. The equations for the background evolution and perturbations are given full generality any parametrization Lagrangian, we stress that apparent singularities sometimes artifacts a pathological choice variables. Adopting phenomenological viewpoint, i.e., from observations back to theory, show knowledge luminosity distance as function redshift up $z\ensuremath{\sim}1\ensuremath{-}2,$ which is expected near future, severely constrains viable subclasses theories. This due requirement positive energy both graviton scalar partner. Assuming particular form Hubble diagram, consistent with present experimental data, reconstruct microscopic Lagrangian various models, find most reasonable ones obtained if universe (marginally) closed.