Modular symmetry in magnetized/intersecting D-brane models
  We study the modular symmetry in four-dimensional low-energy effective field theory, which is derived from type IIB magnetized D-brane models and type IIA intersecting D-brane models. We analyze modular symmetric behaviors of perturbative terms and non-perturbative terms induced by D-brane instanton effects. Anomalies are also investigated and such an analysis on anomalies suggests corrections in effective field theory. 
Tatsuo Kobayashi, Satoshi Nagamoto, Shohei Uemura
hep-th hep-ph