Cosmological Model in Minimal Theory of Mass-Varying Massive Gravity
Ahmad Khoirul Falah(a*), Andy Octavian Latief(b), Husin Alatas(c,d), Bobby Eka Gunara(a,d)

(a) Theoretical Physics Laboratory, Theoretical High Energy Physics Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, Indonesia, 40132.
(*) akhoirulfalah94[at]students.itb.ac.id
(b) Physics of Magnetism and Photonics Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10 Bandung, Indonesia, 40132.
(c) Theoretical Physics Division, Department of Physics, IPB University (Bogor Agricultural University), Jl. Meranti, Kampus IPB Darmaga, Bogor 16680, Indonesia.
(d) Indonesian Center for Theoretical and Mathematical Physics (ICTMP)

Abstract

It is well known that the unique ghost-free Lorentzian nonlinear massive gravity i.e. de Rham-Gabadadze-Tolley (dRGT) theory suffer from nonlinear instability in standard homogen and isotropic cosmology. An extension of dGRT theory so-called the mass-varying massive gravity (MVMG) be able to rescue from this issue by promoting extra dynamical scalar field with potential function play a role as graviton mass. On the other hand there is growing interest in minimal theory of massive gravity (MTMG) whose modifies number degree of freedom in equals to general relativity but background evolution equals to dRGT. Here, we propose a new modfied theory of massive gravity by combining two ideas in MVMG and MTMG, we call it minimal theory of mass-varying massive gravity (MTMVMG). In contrast with conventional MVMG where the graviton mass asymptotically approaches zero and become standard quintessence at late-times, we find that in MTMVMG can provide a good description both in massless and massive. In particular, we discuss MTMVMG under inflationary scenario where the extra scalar field is identified with the inflaton and calculate primordial scalar and tensor perturbations.

Keywords: modified gravity, massive gravity, cosmological model.

Topic: Theoretical High Energy Physics