Adding Charges to N=4 Dyons

TL;DR

This work extends the ${\cal N}=4$ dyon spectrum to a wider class of electric and magnetic charges by incorporating collective excitations of the original system in Type IIB on ${K3}\times T^2$ (and related orbifolds). The authors show that, despite these deformations, the dyon degeneracy is still captured by the same modular function $f$ and depends only on the T-duality invariants $Q^2$, $P^2$, and $Q\cdot P$, after accounting for explicit shift contributions from fluxes and background interactions. They derive explicit expressions for the shifted charge vectors and analyze the impact on the moduli-space walls of marginal stability, ensuring consistency with prior results across the relevant domains. The discussion also covers avenues for further generalization and the limitations imposed by backreaction and multi-KK monopole dynamics, reinforcing the robustness of the degeneracy formula in broader contexts.

Abstract

The spectrum of dyons in a class of N=4 supersymmetric string theories has been found for a specific set of electric and magnetic charge vectors. We extend the analysis to more general charge vectors by considering various charge carrying collective excitations of the original system.