Inflation induced by gravitino condensation in supergravity

Abstract

We discuss the emergence of an inflationary phase in supergravity with the super-Higgs effect due to dynamical spontaneous breaking of supersymmetry, in which the rôle of the inflaton is played by the gravitino condensate. Realistic models compatible with the Planck satellite CMB data are found in conformal supergravity scenarios with dynamical gravitino masses that are small compared to the Planck mass, as could be induced by a non-trivial vacuum expectation value of the dilaton superfield of appropriate magnitude.

Reconstructions of the dark-energy equation of state and the inflationary potential

“…Since they lead to different inflationary scenarios, particularly in respect of the density fluctuations produced, they have different observational consequences for the cosmic microwave background radiation, and this permits them to be finely constrained by observational data. Various inflaton potentials in general relativistic scalar field cosmology have been proposed in [5][6][7][8][9][10][11][12][13][14][15][16][17][18] , while for inflationary models in other gravity theories, where there are more possibilities, see [1,[19][20][21][22][23][24][25][26][27][28][29][30] and references therein.…”

Supersymmetry, Cosmological Constant and Inflation: Towards a fundamental cosmic picture via “running vacuum”

“…For phenomenological reasons which have been outlined in detail in refs. [19,20], and we shall discuss below, we adopt an extension of N = 1 SUGRA which incorporates local supersymmetry in the Jordan frame, enabled by an associated dilaton superfield [14]. The scalar component ϕ of the latter can be either a fundamental space-time scalar mode of the gravitational multiplet, i.e.…”

“…[19,20], phenomenologically realistic situations, where one avoids transplanckian gravitino masses, for supersymmetry breaking scales f at most of order of the Grand Unification (GUT) scale 10 15−16 GeV, as expected from arguments related to the stability of the electroweak vacuum, can occur only for largeκ couplings, typically of orderκ ∼ 10 3 − 10 4 κ. Given the relation (9) this corresponds to dilaton vev of O (−10), where the negative sign may be familiar in the context of dilaton-influenced cosmological scenarios [33].…”

“…The supersymmetry breaking occurs dynamically via the formation of gravitino condensates, as a consequence of the four-gravitino interactions that characterise (any) supergravity action, via the fermionic torsion parts of the spin connection. The approach is documented in a series of previous publications [19][20][21] and will be reviewed briefly here. We should stress that our approach does not supersymmetrise higher curvature terms in the action to obtain Starobinksy-like effective actions, as e.g.…”

“…Since this must be an energetically favourable process to occur, it then follows that the effective potential experienced by the gravitino condensate must be locally concave about the origin. The corresponding one-loop effective potential of the gravitino condensate scalar field, therefore, has the characteristic form of a Coleman-Weinberg double well potential, offering the possibility of hilltop-type inflation, with the condensate field playing the role of the inflaton [19,20], which would be the simplest scenario. However, in order to guarantee a slow-roll inflation one needs unnaturally large values of the gravitino-condensate wave function renormalisation, unless transplanckian scales for supersymmetry breaking are invoked.…”