Largescale structure perturbation theory without losing stream crossing
Abstract
Here, we suggest an approach to perturbative calculations of largescale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel’dovich evolution, with terms that can be computed exactly even for streamcrossed displacements. We evaluate the oneloop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with Nbody simulations compared to the Zel’dovich power spectrum (which is exact in 1D up to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effectivetheorylike regulation of smallscale fluctuations without free parameters.
 Authors:
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Publication Date:
 Research Org.:
 SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1419985
 Grant/Contract Number:
 AC0276SF00515
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Physical Review D
 Additional Journal Information:
 Journal Volume: 97; Journal Issue: 2; Journal ID: ISSN 24700010
 Publisher:
 American Physical Society (APS)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTRONOMY AND ASTROPHYSICS
Citation Formats
McDonald, Patrick, and Vlah, Zvonimir. Largescale structure perturbation theory without losing stream crossing. United States: N. p., 2018.
Web. doi:10.1103/physrevd.97.023508.
McDonald, Patrick, & Vlah, Zvonimir. Largescale structure perturbation theory without losing stream crossing. United States. doi:10.1103/physrevd.97.023508.
McDonald, Patrick, and Vlah, Zvonimir. 2018.
"Largescale structure perturbation theory without losing stream crossing". United States.
doi:10.1103/physrevd.97.023508.
@article{osti_1419985,
title = {Largescale structure perturbation theory without losing stream crossing},
author = {McDonald, Patrick and Vlah, Zvonimir},
abstractNote = {Here, we suggest an approach to perturbative calculations of largescale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel’dovich evolution, with terms that can be computed exactly even for streamcrossed displacements. We evaluate the oneloop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with Nbody simulations compared to the Zel’dovich power spectrum (which is exact in 1D up to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effectivetheorylike regulation of smallscale fluctuations without free parameters.},
doi = {10.1103/physrevd.97.023508},
journal = {Physical Review D},
number = 2,
volume = 97,
place = {United States},
year = 2018,
month = 1
}

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