A note on viability of nonminimally coupled $f(R)$ theory

Abstract

Consistency conditions for nonminimally coupled $f(R)$ theories have been derived by requiring the absence of tachyons and instabilities in the scalar fluctuations. This note confirms these results and clarifies a subtlety regarding different definitions of sound speeds.

4 pages. -added acknowledgement

References in corpus (3)

• Generalized curvature-matter couplings in modified gravity
• Primordial perturbations and non-Gaussianities in DBI and general multi-field inflation
• On the consistency of non-minimally coupled f(R) gravity

Cited by in corpus (3)

• In the Realm of the Hubble tension $-$ a Review of Solutions
• Dynamical systems applied to cosmology: dark energy and modified gravity
• Complexity Factor For Anisotropic Source in Non-minimal Coupling Metric $f(R)$ Gravity