Non-linear matter power spectrum from Time Renormalisation Group: efficient computation and comparison with one-loop

Jun, 2011
26 pages
Published in:
  • JCAP 10 (2011) 037
e-Print:
Report number:
  • CERN-PH-TH-2011-097,
  • LAPTH-014-11

Citations per year

20122015201820212024012345
Abstract: (arXiv)
We address the issue of computing the non-linear matter power spectrum on mildly non-linear scales with efficient semi-analytic methods. We implemented M. Pietroni's Time Renormalization Group (TRG) method and its Dynamical 1-Loop (D1L) limit in a numerical module for the new Boltzmann code CLASS. Our publicly released module is valid for LCDM models, and optimized in such a way to run in less than a minute for D1L, or in one hour (divided by number of nodes) for TRG. A careful comparison of the D1L, TRG and Standard 1-Loop approaches reveals that results depend crucially on the assumed initial bispectrum at high redshift. When starting from a common assumption, the three methods give roughly the same results, showing that the partial resumation of diagrams beyond one loop in the TRG method improves one-loop results by a negligible amount. A comparison with highly accurate simulations by M. Sato & T. Matsubara shows that all three methods tend to over-predict non-linear corrections by the same amount on small wavelengths. Percent precision is achieved until k~0.2 h/Mpc for z>2, or until k~0.14 h/Mpc at z=1.
Note:
  • 24 pages, 7 figures, revised title and conclusions, version accepted in JCAP, code available at http://class-code.net