Anomalies and Nonsupersymmetric D-Branes

May 1, 2023
38 pages
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202220232024054
Abstract: (arXiv)
We revisit some aspects of D-brane theory from the point of view of anomalies. When the boundary condition on a worldsheet boson is flipped from Neumann to Dirichlet, worldsheet supersymmetry requires also reversing the sign of the boundary condition of the corresponding worldsheet fermion. This induces an anomaly which is a mod 2 anomaly in Type II superstring theory and a mod 8 anomaly in Type I superstring theory. The same anomaly also receives contributions from a sign in the sum over bulk spin structures (in Type IIA superstring theory), Chan-Paton factors of symplectic type (in Type I superstring theory), and Majorana fermions that propagate only on the worldsheet boundary. The need to cancel the anomaly accounts for many properties of supersymmetric and especially nonsupersymmetric D-branes in Type I and Type II superstring theory.
Note:
  • 38 pp, minor corrections in v. 2
  • fermion: Majorana
  • anomaly
  • superstring
  • D-brane
  • boundary condition
  • structure
  • Chan-Paton factor
  • symplectic
  • spin