Covariance of the matter power spectrum including the survey window
  function effect: N-body simulations vs. fifth-order perturbation theory on
  grid
  We present a Next-to-next-to-leading (fifth or NNLO) order calculation for
the covariance matrix of the matter power spectrum, taking into account the
effect of survey window functions. Using the grid-based calculation scheme for
the standard perturbation theory, GridSPT, we quickly generate multiple
realizations of the nonlinear density fields to fifth order in perturbation
theory, then estimate the power spectrum and the covariance matrix from the
sample. To the end, we have obtained the non-Gaussian covariance originated
from the one-loop trispectrum without explicitly computing the trispectrum. By
comparing the GridSPT calculations with the N-body results, we show that NNLO
GridSPT result reproduces the N-body results on quasi-linear scales where SPT
accurately models nonlinear matter power spectrum. Incorporating the survey
window function effect to GridSPT is rather straightforward, and the resulting
NNLO covariance matrix also matches well with the N-body results.
