Fayet–Iliopoulos terms in supergravity and D-term inflation

Abstract

We analyse the consequences of a new gauge invariant Fayet-Iliopoulos (FI) term proposed recently to a class of inflation models driven by supersymmetry breaking with the inflaton being the superpartner of the goldstino. We first show that charged matter fields can be consistently added with the new term, as well as the standard FI term in supergravity in a Kähler frame where the U (1) is not an Rsymmetry. We then show that the slow-roll conditions can be easily satisfied with inflation driven by a D-term depending on the two FI parameters. Inflation starts at initial conditions around the maximum of the potential where the U (1) symmetry is restored and stops when the inflaton rolls down to the minimum describing the present phase of our Universe. The resulting tensor-to-scalar ratio of primordial perturbations can be even at observable values in the presence of higher order terms in the Kähler potential.

Liberated $$ \mathcal{N} $$ = 1 supergravity

“…These novel results indicate that all the effects that have been studied with constrained superfields and nonlinear realizations of supersymmetry can be instead studied with supersymmetry linearly realized. Let us note in passing that models for inflation utilizing the setup of [26] have been studied in [28,29]. 1 In this work we do one further step towards this new direction.…”

“…Therefore an N = 1 supersymmetric background will require both U and D I W to vanish. We will now discuss in more detail what happens in the limit 29) JHEP06 (2018)011 where supersymmetry will be restored. If we wish to have a generic U function entering (3.5) then the limit (3.29) has to be excluded from the moduli space of the effective supergravity theory, because all fermionic terms will diverge.…”

New Kähler invariant Fayet–Iliopoulos terms in supergravity and cosmological applications

“…In the presence of matter, the construction of [5] leads to a scalar potential but breaks Kähler invariance. On the other hand, the new and standard FI-terms can coexist in the case of gauge Rsymmetry, providing interesting models of D-term inflation [6]. An alternative construction was made in [7] preserving Kähler invariance and leading to a constant FI-term in the presence of matter, that generates a constant uplift of the vacuum energy.…”

On (Multi-)Center branes and exact string vacua

“…In the case of NS5-branes, we may find an exact CFT description for the background (14) in two limiting cases. For N = 1, corresponding to k NS5-branes at a single point, it is known that the exact description is in terms of the SU(2) k × U(1) Q WZW model, where Q = 2 k+2 is the background charge associated with the U(1) factor [4,5]. An exact CFT description is also possible when N ≫ 1 [3].…”

“…We show that in the case of NS5-branes, where R-R fields are absent, there exist exact conformal field theory (CFT) descriptions in a number of interesting cases. The well known example corresponds to the SU(2)×U(1) WZW model CFT [4], representing the throat of a semi-wormhole, as the near horizon geometry of NS5 branes [5] at one center. A less known example corresponds to a specific limit of non-extremal NS5 branes (at one center), where the string coupling and nonextremality parameter both go to zero with their ratios held fixed.…”