Cosmological Imprints of SUSY Breaking in Models of Sgoldstinoless Non-Oscillatory Inflation

TL;DR

This paper explores how supersymmetry breaking influences non-oscillatory inflation models in supergravity, revealing potential observable effects like primordial black holes and modifications to cosmic microwave background signals.

Contribution

It introduces models stabilizing the sgoldstino near the origin, analyzing back-reaction effects and their impact on inflationary observables and primordial black hole formation.

Findings

Small sgoldstino fluctuations can significantly affect cosmological evolution.

Large supersymmetry breaking scales can produce peaks in the scalar power spectrum.

Primordial black holes of various masses may form due to these effects.

Abstract

In supergravity, the dynamics of the sgoldstino -- superpartner of the goldstino superfield associated with the breaking of supersymmetry at low energy -- can substantially modify the dynamics of inflation in the primordial Universe. So-called sgoldstinoless models assume the existence of a nilpotency constraint $S^2=0$ that effectively removes the sgoldstino from the theory. Such models were proposed to realise non-oscillatory inflation scenarios with a single scalar field, which feature a long period of kination at the end of inflation, and therefore a non-standard post-inflationary cosmology. Using effective operators, we propose models in which the sgoldstino is stabilized close to the origin to reproduce the nilpotent constraint. We show that small sgoldstino fluctuations may lead to a sizeable back-reaction on the cosmological history. We study the effect of this back-reaction on the inflation observables measured in the cosmic microwave background and confront the model to a series of constraints including limits on $\Delta N_{\rm eff}$. We show that the peculiar form of the potential in the large supersymmetry breaking scale limit can generate peaks in the scalar power spectrum produced from inflation. We study how certain perturbation modes may re-enter the horizon during or after kination and show that a large supersymmetry breaking scale may lead to the formation of primordial black holes with various masses in the early Universe.