[Paper Review] The BOSS bispectrum analysis at one loop from the Effective Field Theory of Large-Scale Structure

Guido D’Amico, Yaniv Donath+3 more|arXiv (Cornell University)|Jun 16, 2022

Particle physics theoretical and experimental studies121 references26 citations

TL;DR

This paper presents a high-precision cosmological analysis of BOSS galaxy clustering data using the Effective Field Theory of Large-Scale Structure (EFTofLSS) at one-loop order for the power spectrum and bispectrum monopole, and tree level for the bispectrum quadrupole. It achieves a 30% reduction in error bars on σ₈, 18% on h, and 13% on Ωₘ compared to power-spectrum-only analyses, yielding σ₈ = 0.794 ± 0.037, h = 0.692 ± 0.011, and Ωₘ = 0.311 ± 0.010 at 68% CL, with no tension with Planck data.

ABSTRACT

We analyze the BOSS power spectrum monopole and quadrupole, and the bispectrum monopole and quadrupole data, using the predictions from the Effective Field Theory of Large-Scale Structure (EFTofLSS). Specifically, we use the one loop prediction for the power spectrum and the bispectrum monopole, and the tree level for the bispectrum quadrupole. After validating our pipeline against numerical simulations as well as checking for several internal consistencies, we apply it to the observational data. We find that analyzing the bispectrum monopole to higher wavenumbers thanks to the one-loop prediction, as well as the addition of the tree-level quadrupole, significantly reduces the error bars with respect to our original analysis of the power spectrum at one loop and bispectrum monopole at tree level. After fixing the spectral tilt to Planck preferred value and using a Big Bang Nucleosynthesis prior, we measure $σ_8=0.794\pm 0.037$, $h = 0.692\pm 0.011$, and $Ω_m = 0.311\pm 0.010$ to about $4.7\%$, $1.6\%$, and $3.2\%$, at $68\%$ CL, respectively. This represents an error bar reduction with respect to the power spectrum-only analysis of about $30\%$, $18\%$, and $13\%$ respectively. Remarkably, the results are compatible with the ones obtained with a power-spectrum-only analysis, showing the power of the EFTofLSS in simultaneously predicting several observables. We find no tension with Planck.

Motivation & Objective

• To improve cosmological constraints from BOSS galaxy clustering data by incorporating higher-order statistics beyond the power spectrum.
• To test the predictive power of the EFTofLSS framework at one-loop order for both the power spectrum and bispectrum.
• To reduce uncertainties in ΛCDM parameters by including the one-loop bispectrum monopole and tree-level bispectrum quadrupole.
• To validate the analysis pipeline against numerical simulations and ensure internal consistency.
• To assess compatibility with Planck and BBN priors, particularly regarding the Hubble tension and primordial non-Gaussianity.

Proposed method

• Uses one-loop EFTofLSS predictions for the power spectrum monopole and quadrupole, and the bispectrum monopole.
• Applies tree-level EFTofLSS for the bispectrum quadrupole to capture redshift-space distortions and anisotropic clustering.
• Employs IR-resummation to account for long-wavelength modes and improve convergence at large scales.
• Incorporates window functions and Alcock-Paczynski corrections to model survey geometry and observational effects.
• Applies binning procedures to the bispectrum using Legendre polynomial decomposition and spherical Bessel function integrals.
• Performs a full likelihood analysis with priors on baryon abundance from Big Bang Nucleosynthesis and spectral tilt from Planck.

Experimental results

Research questions

• RQ1 How much do error bars on ΛCDM parameters improve when including one-loop bispectrum monopole and tree-level bispectrum quadrupole in the analysis?
• RQ2 To what extent does the EFTofLSS framework at one-loop order accurately describe BOSS data across multiple clustering statistics?
• RQ3 Are the resulting cosmological constraints consistent with Planck and BBN priors, especially regarding the Hubble constant and matter density?
• RQ4 What is the impact of including higher-order statistics (bispectrum) on the precision of σ₈, h, and Ωₘ measurements compared to power-spectrum-only analysis?
• RQ5 How robust is the analysis pipeline against systematics, and does it pass validation tests against numerical simulations?

Key findings

• The inclusion of the one-loop bispectrum monopole and tree-level bispectrum quadrupole reduces error bars on σ₈ by approximately 30% compared to a power-spectrum-only analysis.
• Error bars on h are reduced by about 18%, and on Ωₘ by about 13%, demonstrating significant improvement in cosmological parameter precision.
• The final constraints are σ₈ = 0.794 ± 0.037, h = 0.692 ± 0.011, and Ωₘ = 0.311 ± 0.010 at 68% confidence level.
• The results are fully compatible with Planck's preferred values and show no tension with the CMB or BBN priors.
• The analysis pipeline successfully passes internal consistency checks and validation against numerical simulations.
• The EFTofLSS framework demonstrates strong predictive power by simultaneously fitting multiple observables (Pℓ, B₀, B₂) with a single consistent model.