Abstract
In this work we shall introduce a theoretical framework comprised by a non-minimal coupled canonical scalar field, a non-minimal coupling to the Gauss-Bonnet invariant and a non-minimal kinetic coupling. This theoretical framework is basically a non-minimally coupled Einstein-Gauss-Bonnet theory with extra corrections of the form of a non-minimal kinetic coupling. In order to comply with the GW170817 event, we shall impose a constraint on the propagation speed of the primordial tensor perturbations that it is equal to that of light's in vacuum, and this constraint basically specifies the way that the scalar potential and the non-minimal couplings of the theory can be chosen. The whole theoretical framework, which belongs to the larger class of Horndeski theories, cannot yield viable results, due to the fact that the primordial gravitational wave speed is not equal to that of light's. Thus we study this theory by also imposing the constraint of having gravity wave speed equal to the light speed. We directly examine the inflationary phenomenology of our theoretical framework and by assuming the slow-roll conditions, we derived the equations of motion in such a way so that analytical results may be extracted. By using several well motivated models we demonstrate the framework leads to a viable phenomenology.
Highlights
The striking GW170817 event [1] of the merging of two neutron stars has affected significantly the perspective of theoretical cosmologists for modified gravity theories
In this work we developed a theoretical framework that practically revived non-minimally coupled Horndeski theories with non-minimal kinetic coupling
The effective Lagrangian of this model consists of three parts, of a canonical scalar field theory non-minimally coupled to gravity, a non-minimal coupling of the scalar field to the Gauss-Bonnet invariant, and a non-minimal kinetic coupling term
Summary
The striking GW170817 event [1] of the merging of two neutron stars has affected significantly the perspective of theoretical cosmologists for modified gravity theories. By exploiting several appropriately chosen models, and by using several well motivated slow-roll compatible approximations, we demonstrate that the theoretical framework of non-minimally coupled Einstein-Gauss-Bonnet theory can produce a viable inflationary phenomenology and at the same time it can be compatible with the GW170817 event, since the propagation speed of the tensor perturbations, the primordial gravitations wave speed, is equal to that of light’s. The experiments will verify if a theoretical framework is consistent or not, like the LHC experiment did with many theoretical approaches Another motivation for studying extended Einstein-Gauss-Bonnet theories, is that these theories are basically string corrections, and since inflation occurs chronologically quite close to the Planck era, it might be possible that such string corrections appear in the effectively inflationary Lagrangian
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
