Racetrack Inflation and Cosmic Strings
  We consider the coupling of racetrack inflation to matter fields as realised in the D3/D7 brane system. In particular, we investigate the possibility of cosmic string formation in this system. We find that string formation before or at the onset of racetrack inflation is possible, but they are then inflated away. Furthermore, string formation at the end of inflation is prevented by the presence of the moduli sector. As a consequence, no strings survive racetrack inflation. 
Philippe Brax, Carsten van de Bruck, Anne-Christine Davis, Stephen C.   Davis, Rachel Jeannerot and Marieke Postma