Cosmology with orthogonal nilpotent superfields

Abstract

We study the application of a supersymmetric model with two constrained supermultiplets to inflationary cosmology. The first superfield S is a stabilizer chiral superfield satisfying a nilpotency condition of degree 2, S 2 ¼ 0. The second superfield Φ is the inflaton chiral superfield, which can be combined into a real superfield B ≡ 1 2i ðΦ −ΦÞ. The real superfield B is orthogonal to S, SB ¼ 0, and satisfies a nilpotency condition of degree 3, B 3 ¼ 0. We show that these constraints remove from the spectrum the complex scalar sgoldstino, the real scalar inflaton partner (i.e. the "sinflaton"), and the fermionic inflatino. The corresponding supergravity model with de Sitter vacua describes a graviton, a massive gravitino, and one real scalar inflaton, with both the goldstino and inflatino being absent in unitary gauge. We also discuss relaxed superfield constraints where S 2 ¼ 0 and SΦ is chiral, which removes the sgoldstino and inflatino, but leaves the sinflaton in the spectrum. The cosmological model building in both of these inflatino-less models offers some advantages over existing constructions.

Scanning of the supersymmetry breaking scale and the gravitino mass in supergravity

“…These models have been studied in [35][36][37] for standard chiral superfields. It is interesting that couplings like (5.8) of the three-form superfield to the inflaton have been studied in [33].…”

“…To further simplify the model, we will use a constraint which has become very useful in supergravity cosmology [35][36][37] for the description of the inflationary sector. The constraint we impose on A is…”

Cosmology and supergravity

“…It also avoids goldstino-inflatino mixing, which makes matter creation in the Early Universe very complicated. In the unitary gauge, the inflatino field simply vanishes, since it is proportional to the goldstino 53,56 . In Table 4 we collect the various orthogonality constraints.…”

From linear to non-linear SUSY and back again

“…In this spirit, constrained superfields have been used for the effective description of inflationary models that are embedded in supergravity [15][16][17][18][19][20][21][22][23][24][25][26], but also to study more general brane supersymmetry breaking scenarios in string theory reductions to four dimensions. While explicit string constructions based on tachyon-free non-BPS systems are known since some time [27][28][29] and their non-linear supersymmetry has been studied in detail [30,31], their connection with the constrained superfields are still not fully understood [32][33][34][35][36][37][38].…”