Small field axion inflation with sub-Planckian decay constant
  We study an axion inflation model recently proposed within the framework of type IIB superstring theory, where we pay a particular attention to a sub-Planckian axion decay constant. Our axion potential can lead to the small field inflation with a small tensor-to-scalar ratio, and a typical reheating temperature can be as low as GeV. 
Kenji Kadota, Tatsuo Kobayashi, Akane Oikawa, Naoya Omoto, Hajime   Otsuka, and Takuya H. Tatsuishi
hep-ph astro-ph.CO hep-th