Inflation with antisymmetric tensor field: new candidates

Abstract

We study classes of inflation models driven by antisymmetric tensor field, with minimal and nonminimal couplings to gravity, that address the known issues of such models considered in the past. First, we show that with a different choice of the background structure of the antisymmetric tensor field, inflation is supported even for the minimal model with quadratic potential contrary to past results. We also include the nonminimal coupling to gravity and analyse perturbations to the antisymmetric tensor as well as the tensor modes of perturbed metric. The two models differ in terms of the behaviour of tensor modes, where the speed of the gravitational wave can be tuned to c in the latter model. The power spectrum and spectral index receive slight scale dependence. Finally, we consider a quartic potential motivated by the graceful exit to reheating phase, which requires a nonminimal coupling to support inflation. The two tensor modes of the perturbed metric are found to evolve differently in this model, and give rise to a highly scale-dependent power spectrum.

Ultraviolet unitarity violations in non-minimally coupled scalar-Starobinsky inflation

“…To explain away the remainder of the issues, multitudes of inflationary models have been proposed over the past few decades [12,13]. For modifications on the matter side, these include noncanonical scalar models [14], or models that replace the scalar field with, say, a JCAP01(2023)029 massive vector field [15][16][17][18], fermionic field [19][20][21][22], antisymmetric tensor field [23][24][25][26][27], and models involving nonminimal couplings with these fields, all of which require the introduction of new physics. Apart from these, there have been several propositions that hold the Standard Model of particle physics to be fundamental and intend not to modify that and instead propose modifications on the gravity side.…”

Ultraviolet Unitarity Violations in Non-minimally Coupled Scalar-Starobinsky Inflation

“…To explain away the remainder of the issues, multitudes of inflationary models have been proposed over the past few decades [15]. For modifications on the matter side, these include noncanonical scalar models [16], or models that replace the scalar field with, say, a massive vector field [17][18][19][20], fermionic field [21,22], antisymmetric tensor field [23][24][25][26][27], and models involving nonminimal couplings with these fields, all of which require the introduction of new physics. Apart from these, there have been several propositions that hold the Standard Model of particle physics to be fundamental and intend not to modify that and instead propose modifications on the gravity side.…”