Influence on Starobinsky inflation by other fields with large amplitude
  The Starobinsky model is one of the inflation models consistent with the result of CMB observation by the Planck satellite. We consider the dynamics of the Starobinsky inflation in the presence of another scalar field with a large expectation value during inflation due to a negative Hubble-induced mass. We find that it would be affected if the other field has an amplitude close to the Planck scale. In this case, we may observe such effects on the Starobinsky model by future CMB experiments. 
Shinta Kasuya and Kanto Moritake
hep-ph astro-ph.CO