The D0$-$D8 system revisited

Abstract

We address a few subtle issues regarding the interacting D0-D8 system. There are two existing interpretations for the counter-intuitive non-vanishing cylinder-diagram R-R potential. We improve them each by properly dealing with the divergence of potential in the R-R as well as the NS-NS sector, which has been ignored so far. We further test them by considering the D8 to carry a flux, electric or magnetic. We find that the improved interpretations continue to hold. We resolve a subtle issue regarding the regularization of fermionic zero-modes in the R-R sector when the D8 carries an electric flux so that a meaningful result for the potential can be calculated. The persistence of divergence for the potential in either sector in the presence of a flux on the D8 brane indicates that adding a flux/fluxes on the D8 brane doesn't help to improve its nature of existence as an independent object, therefore reenforcing the previous assertion on D8 branes.

19 pages, no figures, references updated and discussion expanded, the version to appear in JHEP