D-brane Solitons in Supersymmetric Sigma-Models
Jerome P. Gauntlett, Rubén Portugues, David Tong, Paul K. Townsend
TL;DR
The paper investigates D-brane-like solitons in massive D=4 N=2 supersymmetric sigma-models, revealing a static 1/4-supersymmetric kink-lump (a string ending on a wall) and a time-dependent Q-kink-lump, with a BIon interpretation on the D=4 DBI action. It provides explicit BPS-type constructions via a holomorphic data Z(z) that unify kink-lump, Q-kink-lump, and Q-lump configurations, all preserving 1/4 of the sigma-model supersymmetry. The authors establish an effective D=4 DBI description on the domain wall, including a boosted, magnetic-background generalization, and demonstrate that the kink-lump corresponds to a BIon on the wall’s fluctuations; these solutions lift to M5-brane configurations in a multi-M-monopole background, identified as Q-calibrated branes. Overall, the work links field-theoretic D-brane solitons to BIon physics and M-theory calibrations, introducing the notion of Q-calibration for time-dependent minimal-energy configurations and providing a framework for nonperturbative brane dynamics in curved target spaces.
Abstract
Massive D=4 N=2 supersymmetric sigma models typically admit domain wall (Q-kink) solutions and string (Q-lump) solutions, both preserving 1/2 supersymmetry. We exhibit a new static 1/4 supersymmetric `kink-lump' solution in which a string ends on a wall, and show that it has an effective realization as a BIon of the D=4 super DBI-action. It is also shown to have a time-dependent Q-kink-lump generalization which reduces to the Q-lump in a limit corresponding to infinite BI magnetic field. All these 1/4 supersymmetric sigma-model solitons are shown to be realized in M-theory as calibrated, or `Q-calibrated', M5-branes in an M-monopole background.