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

Authors :: Tomi S. Koivisto
Nicola Tamanini
Service de Physique Théorique (SPhT)
Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Service de Physique Théorique ( SPhT )
Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Centre National de la Recherche Scientifique ( CNRS )
Source :: Gen.Rel.Grav., Gen.Rel.Grav., 2016, 48 (7), pp.97. ⟨10.1007/s10714-016-2087-5⟩, Gen.Rel.Grav., 2016, 48 (7), pp.97. 〈10.1007/s10714-016-2087-5〉
Publication Year :: 2016
Publisher :: Springer Science and Business Media LLC, 2016.
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.<br />Comment: 4 pages. -added acknowledgement