http://arxiv.org/abs/2209.03055
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. 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.
M. Asghari and A. Sheykhi
Thu, 8 Sep 22
20/77
Comments: 13 pages, 6 figures
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