On gauge couplings and thresholds in Type I Gepner models and otherwise

TL;DR

This paper derives formulas for gauge couplings and thresholds in Type I Gepner models, illustrating the method with the Quintic, and explores implications for the Weinberg angle and D-brane correspondences.

Contribution

It provides the first general formulae for gauge couplings and thresholds in Type I models based on interacting N=2 SCFTs like Gepner models.

Findings

Derived tree level gauge couplings and one-loop thresholds for Gepner models.

Applied the formulas to the Quintic Calabi-Yau example.

Discussed the relation between D-branes and N=2 superconformal algebra representations.

Abstract

We derive general formulae for tree level gauge couplings and their one-loop thresholds in Type I models based on genuinely interacting internal N=2 SCFT's, such as Gepner models. We illustrate our procedure in the simple yet non-trivial instance of the Quintic. We briefly address the phenomenologically more relevant issue of determining the Weinberg angle in this class of models. Finally we initiate the study of the correspondence between `magnetized' or `coisotropic' D-branes in Gepner models and twisted representations of the underlying N=2 SCA.