In ation in a scalar-vector-tensor theory

Abstract

In this work, we study in ation in a particular scalar-vector-tensor theory of gravitation without the U(1) gauge symmetry. The model is constructed from the more general action introduced in Heisenberg et al. (Phys Rev D 98:024038, 2018) using certain speci c choices for the Lagrangians and the coupling functions. Also, for this model we build the explicit form for the action, and from it, we derive the general equations: the energy-momentum tensor and the equations of motion, and using the at FLRW background, we have analyzed if it's possible to obtain an in ationary regime with it. Additionally, using particular choices for the potential, the coupling functions, suitable dimensionless coupling constants and initial conditions, it was possible verify numerically that this model of in ation is viable. In this sense, we could verify that the introduction of the coupling function f( ) in our model of in ation, allows us to reach a suitable amount of e-foldings N for su cient in ation. This is a remarkable result, since without the coupling function contribution, the amount of e-foldings is smaller at the end of in ation, as has been demonstrated in Heisenberg et al. (2018). Also, the no-ghosts and stability conditions that the model during in ation must satisfy, i.e., absence of ghosts and Laplacian instabilities of linear cosmological perturbations were obtained, furthermore these conditions were veri ed numerically too.