Solar-System Constraints on f(R) Chameleon Gravity

We investigate the solar-system constraint on the f® theory of modified gravity with chameleon mechanism, where f® represents the deviation from general relativity in the gravity action. We obtain a stringent bound to a general, non-constant deviation function f®: -10^{-15} < df/dR < 0 when R ~ 310^5H0^2, and a loose bound: 0 < Rd(df/dR)/dR < 2/5 when R > 310^5*H0^2, by requiring the thin-shell condition in the solar system, particularly in the atmosphere of the Earth. These bounds can be conveniently utilized to test the f® models with given functional forms of f® and to obtain the constraints on the parameters therein. For demonstration we apply these bounds to several widely considered f® models. (H0: Hubble constant)