Vainshtein screening in a cosmological background in the most general
  second-order scalar-tensor theory
  A generic second-order scalar-tensor theory contains a nonlinear derivative
self-interaction of the scalar degree of freedom $\phi$ \`{a} la Galileon
models, which allows for the Vainshtein screening mechanism. We investigate
this effect on subhorizon scales in a cosmological background, based on the
most general second-order scalar-tensor theory. Our analysis takes into account
all the relevant nonlinear terms and the effect of metric perturbations
consistently. We derive an explicit form of Newton's constant, which in general
is time-dependent and hence is constrained from observations, as suggested
earlier. It is argued that in the most general case the inverse-square law
cannot be reproduced on the smallest scales. Some applications of our results
are also presented.
