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arXiv · 2209.03055

On observational signatures of multi-fractional theory

Mahnaz Asghari·Ahmad Sheykhi
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Abstract

We study the multi-fractional theory with $q$-derivatives, where the multi-fractional measure is considered to be in the time direction. The evolution of power spectra and also the expansion history of the universe are investigated in the $q$-derivatives theory. According to the matter power spectra diagrams, the structure growth would increase in the multi-fractional model, expressing incompatibility with low redshift measurements of large scale structures. Furthermore, concerning the diagrams of Hubble parameter evolution, there is a reduction in the value of Hubble constant which conflicts with local cosmological constraints. Thus, primary numerical investigations imply that $q$-derivatives theory has no potential to relieve observational tensions. We also explore the multi-fractional model with current observational data, principally Planck 2018, weak lensing, supernovae, baryon acoustic oscillations (BAO), and redshift-space distortions (RSD) measurements. Numerical analysis reveals that the degeneracy between multi-fractional parameters makes them remain unconstrained under observations. Furthermore, observational constraints on $H_0$ and $σ_8$, detect no significant departure from standard model of cosmology.

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Mahnaz Asghari, Ahmad Sheykhi. 2023-09-10. On observational signatures of multi-fractional theory. https://doi.org/10.1016/j.dark.2023.101323

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