Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Interpreting cosmological tensions from the effective field theory of torsional gravity

Sheng-Feng Yan, Pierre Zhang, Jie-Wen Chen, Xin-Zhe Zhang, Yi-Fu Cai, Emmanuel N. Saridakis

TL;DR

This work investigates whether tensions in cosmological data, notably the $H_0$ and $σ_8$ discrepancies, can be reconciled within torsional gravity using an effective-field-theory (EFT) approach. By mapping $f(T)$ gravity into the EFT framework, the authors construct two concrete models, $f(T)=-T-2Λ/M_P^2+α T^β$, that preserve early-time LCDM behavior while producing late-time modifications that raise $H_0$ and damp structure growth via a modified $G_{eff}$. They show that these models can fit background expansion (including Pantheon data) and growth observables (via $fσ_8$ and BAO/LSS data), offering a gravitational-origin solution to both tensions. The results suggest that a minimal EFT with torsion can provide a viable alternative to standard ΛCDM and motivate further exploration of $f(T,B)$ extensions and higher-order operators, with future large-scale structure surveys capable of testing the predictions.

Abstract

Cosmological tensions can arise within $Λ$CDM scenario amongst different observational windows, which may indicate new physics beyond the standard paradigm if confirmed by measurements. In this article, we report how to alleviate both the $H_0$ and $σ_8$ tensions simultaneously within torsional gravity from the perspective of effective field theory (EFT). Following these observations, we construct concrete models of Lagrangians of torsional gravity. Specifically, we consider the parametrization $f(T)=-T-2Λ/M_P^2+αT^β$, where two out of the three parameters are independent. This model can efficiently fit observations solving the two tensions. To our knowledge, this is the first time where a modified gravity theory can alleviate both $H_0$ and $σ_8$ tensions simultaneously, hence, offering an additional argument in favor of gravitational modification.

Interpreting cosmological tensions from the effective field theory of torsional gravity

TL;DR

This work investigates whether tensions in cosmological data, notably the and discrepancies, can be reconciled within torsional gravity using an effective-field-theory (EFT) approach. By mapping gravity into the EFT framework, the authors construct two concrete models, , that preserve early-time LCDM behavior while producing late-time modifications that raise and damp structure growth via a modified . They show that these models can fit background expansion (including Pantheon data) and growth observables (via and BAO/LSS data), offering a gravitational-origin solution to both tensions. The results suggest that a minimal EFT with torsion can provide a viable alternative to standard ΛCDM and motivate further exploration of extensions and higher-order operators, with future large-scale structure surveys capable of testing the predictions.

Abstract

Cosmological tensions can arise within CDM scenario amongst different observational windows, which may indicate new physics beyond the standard paradigm if confirmed by measurements. In this article, we report how to alleviate both the and tensions simultaneously within torsional gravity from the perspective of effective field theory (EFT). Following these observations, we construct concrete models of Lagrangians of torsional gravity. Specifically, we consider the parametrization , where two out of the three parameters are independent. This model can efficiently fit observations solving the two tensions. To our knowledge, this is the first time where a modified gravity theory can alleviate both and tensions simultaneously, hence, offering an additional argument in favor of gravitational modification.

Paper Structure

This paper contains 6 sections, 11 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Theoretical background
  3. Model independent analyses
  4. $f(T)$ gravity
  5. Extensions in $f(T, B)$ gravity
  6. Conclusion and discussions

Figures (3)

  • Figure 1: Left panel: Reconstruction of two $f(T)$ models. The cyan and magenta rhombic points denote the numerical results of Model-1 and Model-2, respectively; the brown and blue solid curves are the parametrizations given by Eqs. \ref{['mod1']} and \ref{['mod2']}, respectively. Right panel: Redshift evolution of $G_{\mathrm{eff}}/G_N$ in Model-1 (brown solid line) and Model-2 (blue solid line) and their comparison to the GR case (black dashed line).
  • Figure 2: Left panel: Evolution of the Hubble parameter $H(z)$ in the two $f(T)$ models (purple solid line) and in $\Lambda$CDM cosmology (black dashed line). The red point represents the latest data from extragalactic Cepheid-based local measurement of $H_0$ provided in Riess:2019cxk. Right panel: Evolution of $f\sigma_8$ in Model-1 (brown solid line) and Model-2 (blue solid line) of $f(T)$ gravity and in $\Lambda$CDM cosmology (black dashed line). The green data points are from BAO observations in SDSS-III DR12 Wang:2017wia, the gray data points at higher redshift are from SDSS-IV DR14 Gil-Marin:2018cgoHou:2018ynyZhao:2018jxv, while the red point around $\sim 1.8$ is the forecast from Euclid Taddei:2016iku. The subgraph in the left bottom displays $f \sigma_8$ at high redshift $z = 3 \sim 5$, which shows that the curve of Model-2 is above the one of Model-1 and $\Lambda$CDM scenario and hence approaches $\Lambda$CDM slower than Model-1.
  • Figure 3: Left panel: Distance modulus magnitude $m = 5 \mathrm{log}_{10} D_L(z)+25+M$ in TG and $\Lambda$CDM with Planck close to best fit $H_0$ and $M = -19.45$ (Pantheon close to best fit) vs Pantheon SN data. Right panel: Ratio of modulus distances in TG and $\Lambda$CDM vs Pantheon SN error bars divided by the data.