## Kinetic field theory: Non-linear cosmic power spectra in the mean-field approximation

Matthias Bartelmann, Johannes Dombrowski, Sara Konrad, Elena Kozlikin, Robert Lilow, Carsten Littek, Christophe Pixius, Felix Fabis

SciPost Phys. 10, 153 (2021) · published 23 June 2021

- doi: 10.21468/SciPostPhys.10.6.153
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### Abstract

We use the recently developed Kinetic Field Theory (KFT) for cosmic structure formation to show how non-linear power spectra for cosmic density fluctuations can be calculated in a mean-field approximation to the particle interactions. Our main result is a simple, closed and analytic, approximate expression for this power spectrum. This expression has two parameters characterising non-linear structure growth which can be calibrated within KFT itself. Using this self-calibration, the non-linear power spectrum agrees with results obtained from numerical simulations to within typically $\lesssim10\,\%$ up to wave numbers $k\lesssim10\,h\,\mathrm{Mpc}^{-1}$ at redshift $z = 0$. Adjusting the two parameters to optimise agreement with numerical simulations, the relative difference to numerical results shrinks to typically $\lesssim 5\,\%$. As part of the derivation of our mean-field approximation, we show that the effective interaction potential between dark-matter particles relative to Zel'dovich trajectories is sourced by non-linear cosmic density fluctuations only, and is approximately of Yukawa rather than Newtonian shape.

### Cited by 8

### Authors / Affiliations: mappings to Contributors and Organizations

See all Organizations.-
^{1}Matthias Bartelmann, -
^{2}Johannes Dombrowski, -
^{1}Sara Konrad, -
^{1}Elena Kozlikin, -
^{3}Robert Lilow, -
^{1}Carsten Littek, -
^{1}Christophe Pixius, -
^{1}Felix Fabis

^{1}Ruprecht-Karls-Universität Heidelberg / Heidelberg University^{2}University of Nottingham^{3}Department of Physics, Technion