Is String Phenomenology an Oxymoron?

TL;DR

String phenomenology explores the connection between string theory and observable physics, highlighting its achievements, challenges, and the limited but significant potential for experimental verification in particle physics and cosmology.

Contribution

This paper critically assesses the achievements and limitations of string phenomenology, emphasizing the role of moduli fields and the need for concrete models for experimental testing.

Findings

Most observable implications of string theory are inaccessible to low-energy experiments.

Moduli fields are key low-energy remnants influencing cosmology and supersymmetry breaking.

String phenomenology has significantly contributed to mathematics and understanding of string theory.

Abstract

A brief discussion is presented assessing the achievements and challenges of string phenomenology: the subfield dedicated to study the potential for string theory to make contact with particle physics and cosmology. Building from the well understood case of the standard model as a very particular example within quantum field theory we highlight the very few generic observable implications of string theory, most of them inaccessible to low-energy experiments, and indicate the need to extract concrete scenarios and classes of models that could eventually be contrasted with searches in collider physics and other particle experiments as well as in cosmological observations. The impact that this subfield has had in mathematics and in a better understanding of string theory is emphasised as spin-offs of string phenomenology. Moduli fields, measuring the size and shape of extra dimensions, are highlighted as generic low-energy remnants of string theory that can play a key role for supersymmetry breaking as well as for inflationary and post-inflationary early universe cosmology. It is argued that the answer to the question in the title should be, as usual, {\it No}. Future challenges for this field are briefly mentioned. This essay is a contribution to the conference: "Why Trust a Theory?", Munich, December 2015.