Inflationary observables and string theory
Eva M Silverstein · Oxford University Press eBooks · 2015
This chapter covers the theoretical structure and phenomenology of some basic mechanisms for inflation. A full treatment of the problem requires “ultraviolet completion” because of the sensitivity of inflation to quantum gravity effects, while the observables are elegantly parametrized using low-energy field theory. String theory provides novel mechanisms for inflation, some subject to significant observational tests, for example highly UV-sensitive tensor mode measurements. Although the UV completion is not directly accessible experimentally, some of these mechanisms have helped stimulate more systematic analysis of the space of low-energy theories and signatures relevant for data analysis, including searches for non-Gaussianity and additional structure in the power spectrum. The chapter includes a pedagogical overview of string compactifications, with a focus on candidate inflatons and their symmetry structure. Finally, the chapter considers thought-experimental observables in inflation, developing a generalization of gauge/gravity duality that relies on the structure of the scalar potential in string theory.