Gravitino condensation, supersymmetry breaking and inflation

TL;DR

This paper investigates how gravitino condensation can dynamically break local supersymmetry and potentially drive inflation, revealing that while viable inflation is possible, supersymmetry breaking and inflation are mutually incompatible in simple supergravity models.

Contribution

It demonstrates non-perturbative gravitino mass generation and analyzes the effective potential, showing the potential for inflation driven by gravitino condensates in supergravity.

Findings

Gravitino condensation can generate mass non-perturbatively.

The condensate may act as an inflaton, driving early universe inflation.

Simultaneous supersymmetry breaking and inflation are incompatible in simple models.

Abstract

Motivated by dualistic considerations of the reality of quark condensation in quantum chromodynamics, and the connections of supergravity to the exotic physics of string and M-theory, in this thesis we investigate the dynamical breaking of local supersymmetry via gravitino condensation. We firstly demonstrate non-perturbative gravitino mass generation via this mechanism in flat spacetime, and from this derive the condensate mode wavefunction renormalisation. By then calculating the full canonically normalised one-loop effective potential for the condensate mode about a de Sitter background, we demonstrate that, contrary to claims in the literature, this process may both occur and function in a phenomenologically viable manner. In particular, we find that outside of certain unfortunate gauge choices, the stability of the condensate is intimately tied via gravitational degrees of freedom to the sign of the tree-level cosmological constant. Furthermore, we find that the energy density liberated may provide the necessary inflation of the early universe via an effective scalar degree of freedom, provided by the condensate, acting as the inflaton. However, in so doing we find that simultaneously phenomenologically viable inflation and supersymmetry breaking via this approach are mutually incompatible in the simplest supergravity settings. As this mechanism takes place in the gravitational sector, relying on the ubiquitous gravitino torsion terms, we argue that it can also enjoy a certain universality in the context of supergravity and string theories, in that it does not rely on specific or arbitrary choices of potential and/or matter content. This then allows straightforward transplantation of these results into other settings. We present in detail our findings establishing contact between this scenario and known phenomenology, and discuss future avenues for research.