6D Effective Action of Heterotic Compactification on K3 with nontrivial Gauge Bundles

TL;DR

This paper derives the six-dimensional effective action for heterotic string compactifications on K3 with various gauge bundle backgrounds, analyzing scalar couplings, moduli, and mass generation mechanisms.

Contribution

It provides explicit calculations of the effective action, including couplings and mass terms, for heterotic compactifications on K3 with nontrivial gauge bundles.

Findings

Charged scalar and bundle moduli couplings depend on K3 geometry.

U(1) vector multiplets acquire mass via Stuckelberg mechanism in flux backgrounds.

Explicit form of the D-term potential in these compactifications.

Abstract

We compute the six-dimensional effective action of the heterotic string compactified on K3 for the standard embedding and for a class of backgrounds with line bundles and appropriate Yang-Mills fluxes. We compute the couplings of the charged scalars and the bundle moduli as functions of the geometrical K3 moduli from a Kaluza-Klein analysis. We derive the D-term potential and show that in the flux backgrounds U(1) vector multiplets become massive by a Stuckelberg mechanism.