Parameterised Post-Newtonian Expansion in Screened Regions
  The parameterised post-Newtonian (PPN) formalism has enabled stringent tests
of static weak-field gravity in a theory-independent manner. Here we
incorporate screening mechanisms of modified gravity theories into the
framework by introducing an effective gravitational coupling and defining the
PPN parameters as functions of position. To determine these functions we
develop a general method for efficiently performing the post-Newtonian
expansion in screened regimes. For illustration, we derive all the PPN
functions for a cubic galileon and a chameleon model. We also analyse the
Shapiro time delay effect for these two models and find no deviations from
General Relativity insofar as the signal path and the perturbing mass reside in
a screened region of space.
