New angles on D-branes
J. C. Breckenridge, G. Michaud, R. C. Myers
TL;DR
The paper constructs a low-energy background describing $n$ D-membranes rotated by SU(2) angles, showing the mass density and RR-charge densities saturate a BPS bound and thus preserve $1/4$ of the supersymmetries. It derives an explicit solution using harmonic functions $X_a$ and rotation matrices in SU(2), and conducts a Bogomolnyi bound analysis to establish BPS saturation for specific angle relations. Through a sequence of T-duality transformations along transverse and world-volume directions, it generates angled D3- and D4-brane bound states (and related configurations) that maintain the same SUSY fraction, illustrating the robustness of these angled bound states under string dualities. These results advance understanding of nonperturbative D-brane physics, provide concrete backgrounds for microstate counting in Type II theories, and connect to Lifschytz-type bound-state constructions.
Abstract
A low-energy background field solution is presented which describes several D-membranes oriented at angles with respect to one another. The mass and charge densities for this configuration are computed and found to saturate the BPS bound, implying the preservation of one-quarter of the supersymmetries. T-duality is exploited to construct new solutions with nontrivial angles from the basic one.