Cosmological perturbation theory at three-loop order
  We analyze the dark matter power spectrum at three-loop order in standard
perturbation theory of large scale structure. We observe that at late times the
loop expansion does not converge even for large scales (small momenta) well
within the linear regime, but exhibits properties compatible with an asymptotic
series. We propose a technique to restore the convergence in the limit of small
momentum, and use it to obtain a perturbative expansion with improved
convergence for momenta in the range where baryonic acoustic oscillations are
present. Our results are compared with data from N-body simulations at
different redshifts, and we find good agreement within this range.
