Preheating in the nonminimal derivative coupling to gravity
  We revisit the reheating mechanism after the end of inflation in the non-minimal derivative coupling (NDC) to gravity with quadratic potential. This is because the inflaton of the NDC should describe the slow-roll inflation as well as the preheating stage after the end of inflation. We point out that the non-periodic inflaton solution implies the absence of parametric resonance, compared to the periodic oscillating inflaton for the canonical coupling (CC) to gravity. Furthermore, it is demonstrated that narrow and broad parametric resonances do not appear after the end of inflation in the NDC model by solving the differential equation numerically for the quantum field, which differs from the case of the the CC model obtained by solving Mathieu equation. 
Yun Soo Myung, Young-Jai Park
gr-qc hep-th