Gravitational waves from smooth hybrid new infation
  We calculate the production of the gravitational waves from a double
inflation model with lattice simulations. Between the two inflationary stages,
gravitational waves with a characteristic frequency are produced by
fluctuations of the scalar fields enhanced through parametric resonance. The
wavelength of the produced gravitational waves gets extra redshift during the
second inflationary stage and it can be in the observable range for the direct
gravitational wave detectors. It is found that there is a possibility for the
produced gravitational waves to be detected in the planned experiments.
