Branes at angles and calibrated geometry
  In a recent paper, Ohta and Townsend studied the conditions which must be satisfied for a configuration of two intersecting M5-branes at angles to be supersymmetric. In this paper we extend this result to any number of M5-branes or any number of M2-branes. This is accomplished by interpreting their results in terms of calibrated geometry, which is of independent interest. 
BS Acharya, JM Figueroa-O'Farrill and B Spence