Slow-roll inflation in $f(R,T)$ gravity with a $RT$ mixing term

Abstract

We consider slow-roll inflationary models in a class of modified theories of gravity which contains non-minimal curvature-inflaton couplings, i.e., the f (R, T ) gravity, where R is the Ricci scalar and T is the trace of the inflaton energy-momentum tensor. On top of the minimally coupled T that has been widely investigated in the literature, we further include a RT mixing term in the theory. This mixing term introduces non-minimal derivative couplings and plays an important role in inflationary dynamics. Taking chaotic and natural inflation as examples, we find that the predictions for spectral tilt and the tensor-to-scalar ratio are sensitive to the existence of the RT mixing term. In particular, by turning on this mixing term, it is possible to bring chaotic and natural inflation into better agreement with observational data.

Are f(R, Matter) theories really relevant to cosmology?

“…This approach has been used to claim that f (R, Matter) gravity can explain various cosmological and astrophysical observations. In the context of cosmology, those applications range from inflation [14][15][16][17][18][19] to dark matter [20][21][22] and dark energy [23][24][25].…”

Constraining logarithmic $f(R,T)$ model using Dark Energy density parameter $Ω_Λ$ and Hubble parameter $H_0$

“…al is found to be extremely sound in explaining cosmological phenomena. It has been studied with reference to inflation [14,15,16,17], dark energy [18,19,20,21,22], dark matter [23], wormhole [24,25,26,27,28,29,30], pulsar [31,32], white dwarfs [33], gravitational waves [34,35], scalar field models [36,37], anisotropic models [38,39], bouncing cosmology [40,41], big-bang neucleosysnthesis [42], baryogenesis [43], brane world [44,45] etc. Further, the energy conditions and junction conditions in f (R, T ) gravity have also been studied [46,47,48,49].…”