Effective field theory of dark matter and structure formation: Semianalytical results
Name
Hertzberg-2014-Effective field theory.pdf
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553.17 KB
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Author(s)
Hertzberg, Mark Peter
Date Issued
February 2014
Journal
Physical Review D
Publisher
American Physical Society
Citation
Hertzberg, Mark P. “Effective Field Theory of Dark Matter and Structure Formation: Semianalytical Results.” Phys. Rev. D 89, no. 4 (February 2014). © 2014 American Physical Society
Version
Final published version
Abstract
Complimenting recent work on the effective field theory of cosmological large scale structures, here we present detailed approximate analytical results and further pedagogical understanding of the method. We start from the collisionless Boltzmann equation and integrate out short modes of a dark matter/dark energy dominated universe (ΛCDM) whose matter is comprised of massive particles as used in cosmological simulations. This establishes a long distance effective fluid, valid for length scales larger than the nonlinear scale ∼10 Mpc, and provides the complete description of large scale structure formation. Extracting the time dependence, we derive recursion relations that encode the perturbative solution. This is exact for the matter dominated era and quite accurate in ΛCDM also. The effective fluid is characterized by physical parameters, including sound speed and viscosity. These two fluid parameters play a degenerate role with each other and lead to a relative correction from standard perturbation theory of the form ∼10[superscript −6]c[superscript 2]k[superscript 2]/H[superscript 2]. Starting from the linear theory, we calculate corrections to cosmological observables, such as the baryon-acoustic-oscillation peak, which we compute semianalytically at one-loop order. Due to the nonzero fluid parameters, the predictions of the effective field theory agree with observation much more accurately than standard perturbation theory and we explain why. We also discuss corrections from treating dark matter as interacting or wavelike and other issues.
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevD.89.043521
