On the estimation of gravitational wave spectrum from cosmic domain
  walls
  We revisit the production of gravitational waves from unstable domain walls
analyzing their spectrum by the use of field theoretic lattice simulations with
grid size $1024^3$, which is larger than the previous study. We have recognized
that there exists an error in the code used in the previous study, and the
correction of the error leads to the suppression of the spectrum of
gravitational waves at high frequencies. The peak of the spectrum is located at
the scale corresponding to the Hubble radius at the time of the decay of domain
walls, and its amplitude is consistent with the naive estimation based on the
quadrupole formula. Using the numerical results, the magnitude and the peak
frequency of gravitational waves at the present time are estimated. It is shown
that for some choices of parameters the signal of gravitational waves is strong
enough to be probed in the future gravitational wave experiments.
