U-duality Invariant Dyon Spectrum in type II on T^6

TL;DR

This paper presents a U-duality invariant formula for counting 1/8 BPS dyons in type II string theory on T^6, incorporating discrete invariants of E_{7(7)}(Z) beyond the Cremmer-Julia invariant.

Contribution

It provides the first explicit U-duality invariant degeneracy formula for 1/8 BPS dyons in this setting, including additional discrete invariants.

Findings

Derived a formula depending on Cremmer-Julia and other discrete invariants

Confirmed invariance under U-duality transformations

Enhanced understanding of dyon spectrum in string theory

Abstract

We give a manifestly U-duality invariant formula for the degeneracy of 1/8 BPS dyons in type II string theory on T^6 for a U-duality invariant subset of charge vectors. Besides depending on the Cremmer-Julia invariant the degeneracy also depends on other discrete invariants of E_{7(7)}(Z).