String Model Building in the Age of D-Branes

TL;DR

This paper discusses the impact of string duality on string model building, highlighting challenges and the need for robust criteria like fractional charge beyond weak coupling limits.

Contribution

It examines how string duality questions traditional assumptions and proposes fractional charge as a potential robust criterion for model validation.

Findings

String duality challenges existing string model assumptions.

Fractional charge may serve as a robust criterion beyond weak coupling.

Highlights difficulties in string model building due to duality effects.

Abstract

The string duality revolution calls into question virtually all of the working assumptions of string model builders. A number of difficult questions arise. I use fractional charge as an example of a criterion which one would hope is robust beyond the weak coupling heterotic limit. Talk given at the 5th International Workshop on Supersymmetry and Unification of Fundamental Interactions (SUSY-96), University of Maryland, College Park, May 29 - June 1, 1996.