Charges of twisted branes: the exceptional cases

TL;DR

This paper calculates the charges of twisted D-branes in two exceptional cases, showing they match the untwisted branes' charge groups, by expressing NIM-reps through fusion rules of invariant subalgebras.

Contribution

It provides explicit determination of twisted D-brane charges for SO(8) and E_6 cases using fusion rules, a novel approach for these exceptional cases.

Findings

Charge groups match untwisted branes

NIM-reps expressed via fusion rules

Explicit charge calculations for exceptional cases

Abstract

The charges of the twisted D-branes for the two exceptional cases (SO(8) with the triality automorphism and E_6 with charge conjugation) are determined. To this end the corresponding NIM-reps are expressed in terms of the fusion rules of the invariant subalgebras. As expected the charge groups are found to agree with those characterising the untwisted branes.