Adiabatic media inflation

Abstract

We study the dynamics of inflation driven by an adiabatic self-gravitating medium, extending the previous works on fluid and solid inflation. Such a class of media comprise perfect fluids, zero and finite temperature solids. By using an effective theory description, we compute the power spectrum for the scalar curvature perturbation ζ of constant energy density hypersurface and the comoving scalar curvature perturbation R in the case of slow-roll, super slow-roll and w-media inflation, an inflationary phase with w constant and −1 < w < −1/3. A similar computation is done for the tensor modes. Such a media are characterised by intrinsic entropy perturbations that can give a significant contribution to the power spectrum and can be used to generate the required seed to primordial black holes. In general the Weinberg theorem is violated; thus on super horizon scale neither ζ nor R are conserved and moreover ζ = R; reheating becomes crucial to predict the spectrum of primordial perturbations. We discuss in detail the physical consequence of such a violation.

Boosting GWs in supersolid inflation

“…When the field ϕ 0 is absent, namely M 0 = M 1 = 0 (solid inflation limit), one is back to the standard case where reheating takes place at a constant energy density ρ hypersurface like in [9,20]. The continuity of ζ n can also be shown following the same lines of [20] by a generalization of the procedure given in [30].…”

“…Moreover, the correct implementation of the Stuckelberg trick at the background level requires a non-trivial background for ϕ 0 satisfying (3.2). 5 As discussed in [20] ultra SR is also possible; actually when M2 = 0, as for fluids, this is the only viable regime with small .…”

“…the allowed operators are b, τ Y , τ Z and y and the resulting theory U (b, τ Y , τ Z , y) describes an adiabatic solid in the sense that the entropic perturbation δσ is a conserved quantity as discussed in [15,20]. The term supersolid is reserved to the case where, in addition to the phonons of the solid, also the entropic perturbation δσ propagates.…”

Primordial non-Gaussianity in supersolid inflation

“…(4.5) and generates a slow-roll regime with an almost constant . More details are given in appendix F. Note that in [27] and [28] we defined a bit different potentials named simply Λ-Media, characterised by the fact that ρ Λ + p Λ = 0 worth exactly, not only on their background value. 5 An example of a supersolid that it is also a Λ-Medium, in our notations, is…”

“…As discussed in [9,28], reheating 7 is likely to process primordial perturbations produced during inflation such that the initial conditions for the hot phase are determined by the curvature of constant number density of lattice sites n , given by the operator b. The corresponding curvature perturbation related to the b operator is provided in the spatiallyflat gauge at the linear order by…”