Black Holes and Flop Transitions in M-Theory on Calabi-Yau Threefolds
  We present fivedimensional extreme black hole solutions of M-theory compactified on Calabi-Yau threefolds and study these solutions in the context of flop transitions in the extended Kahler cone. In particular we consider a specific model and present black hole solutions, breaking half of N=2 supersymmetry, in two regions of the extended Kahler cone, which are connected by a flop transition. The conditions necessary to match both solutions at the flop transition are analysed. Finally we also discuss the conditions to obtain massless black holes at the flop transition. 
Ingo Gaida, Swapna Mahapatra, Thomas Mohaupt and Wafic A. Sabra