2013

Cosmological perturbation theory at three-loop order

Blas, Diego, Garny, Mathias, Konstandin, Thomas

Understand

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.

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