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Scale transformations, tree-level perturbation theory and the cosmological matter bispectrum

Authors

  • Jun Pan,

    Corresponding author
    1. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 21 0008, China
    2. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD
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  • Peter Coles,

    1. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD
    2. School of Physics and Astronomy, Cardiff University, Queeens Buildings, The Parade, Cardiff CF24 3AA
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  • István Szapudi

    1. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA
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E-mail: jpan@pmo.ac.cn

ABSTRACT

Scale transformations have played an extremely successful role in studies of cosmological large-scale structure by relating the non-linear spectrum of cosmological density fluctuations to the linear primordial power at longer wavelengths. Here, we generalize this approach to investigate the usefulness of scale transformations for non-linear higher order statistics, specifically the bispectrum. We find that the bispectrum predicted by perturbation theory at tree level can be rescaled to match the results of full numerical simulations in the weakly and intermediately non-linear regimes, especially at high redshifts, with an accuracy that is surprising given the simplicity of the procedure used. This discovery not only offers a simple practical way of calculating the matter bispectrum but also suggests that scale transformations may yet yield even deeper insights into the physics of hierarchical clustering.

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