Field independent cosmic evolution

Abstract

It has been shown earlier that Noether symmetry does not admit a form of F(R) corresponding to an action in which F(R) is coupled to scalar-tensor action for gravity or even for pure F(R) gravity taking anisotropic model into account. Here, we prove that F(R) theory of gravity does not admit Noether symmetry even if it is coupled to Tachyonic field and considering a gauge in addition. To handle such a theory, a general conserved current has been constructed under a condition which decouples higher order curvature part from the field part. This condition in principle, solves for the scale factor, independently. Thus cosmological evolution remains independent of the form of the chosen field, whether it be a scalar or a tachyon.