Inflation and leptogenesis in high-scale supersymmetry

Abstract

No-scale supergravity provides a successful framework for Starobinsky-like inflation models.Two classes of models can be distinguished depending on the identification of the inflaton with the volume modulus, T (C-models), or a matter-like field, φ (WZ-models). When supersymmetry is broken, the inflationary potential may be perturbed, placing restrictions on the form and scale of the supersymmetry breaking sector. We consider both types of inflationary models in the context of high-scale supersymmetry. We further distinguish between models in which the gravitino mass is below and above the inflationary scale. We examine the mass spectra of the inflationary sector. We also consider in detail mechanisms for leptogenesis for each model when a righthanded neutrino sector, used in the seesaw mechanism to generate neutrino masses, is employed.In the case of C-models, reheating occurs via inflaton decay to two Higgs bosons. However, there is a direct decay channel to the lightest right-handed neutrino which leads to non-thermal leptogenesis. In the case of WZ-models, in order to achieve reheating, we associate the matter-like inflaton with one of the right-handed sneutrinos whose decay to the lightest right handed neutrino simultaneously reheats the Universe and generates the baryon asymmetry through leptogenesis.

Building models of inflation in no-scale supergravity

“…This two-body rate would lead to an extremely low reheating temperature: for an inflaton mass M ∼ 10 −5 M P , and µ H ∼ 1 TeV, T RH ∼ 10 −1 eV. We note, however, that in the case of high-scale supersymmetry, 138 where all superpartners except the gravitino are heavier than the inflaton, 65,108,114,[139][140][141][142] the decay to Higgs pairs may be the dominant decay channel. 108,114,141,143 Three-body decays to light scalars are possible and the widths are given by…”

“…in either minimal or no-scale supergravity shifts the Planck-scale minimum. For example, the minimum found in minimal supergravity in Section 2.4 is shifted to 43,104,108,[112][113][114][115] The mass of the Polonyi field is then m z = √ 12m 3/2 /Λ z , which is significantly heavier than in the minimal model when Λ z 1. Strong stabilization in this case can lead to a resolution of the cosmological problems associated with the Polonyi field that were discussed earlier.…”

“…Using the form (128) for the Branch I superpotential, we can derive V from (114) and match to a known solution from Ref. 82:…”

“…Furthermore, we relate the supersymmetry-breaking scale to the inflation scale M (see also Refs. 108,114).…”

“…Finally, we note that there is a lower limit on Λ T coming from the postulated form of the stabilization terms in the Kähler potential. Since these should be treated as effective interactions obtained by integrating out fields with masses O(Λ T ), we require Λ T > √ F T , 108,111,114 and using (160) we find that the limit…”