A double-running inflaton mass for a flat potential and an assisted
  hilltop inflation
  We propose a scenario to flatten inflaton potential for a small-field
slow-roll inflation from the origin. In the scenario, inflaton mass-square gets
through a renormalization group running which depends on not only inflaton
field but also an assisting field. Thanks to the assisting field participating
in the running, initial condition for a slow-roll inflation can be set
naturally, and inflaton potential can be flattened by the vacuum expectation
value of the field. Applying this idea, we propose a scenario of inflation,
dubbed here as \textit{assisted hilltop inflation}, which is free from the
initial condition and the flatness problems of inflation.
