Sep 6 – 12, 2023
Mon-Repos, Corfu, Greece
Europe/Athens timezone

Fractional Cosmology with conformal and nonminimal couplings a possible resolution to H0 tension?

Sep 9, 2023, 4:30 PM
Mon-Repos, Corfu, Greece

Mon-Repos, Corfu, Greece


Prof. Genly Leon Torres (Universidad Catolica del Norte)


Various studies, such as references 2207.00878 [gr-qc], 2304.14465 [gr-qc], and 2304.14465 [gr-qc], have explored the potential of Fractional Cosmology to address the H0 tension. They have analyzed the Equation of State's value attained from the Supernova H0 and Planck's value for z<1.5 and have reported a trend of H0 that aligns with these values. However, there is still a discrepancy between the two values in the range 1.5<z<2.5, indicating that the H0 tension has not been entirely resolved. To expand on this theory, we may assume the Einstein-Hilbert action and a scalar field ϕ to create a nonminimal coupling theory with the coupling ξRϕ^2 of gravity and the scalar field. ξ is the coupling constant, and the simplest and most natural case is minimal coupling where ξ=0. Another viable option is ξ=1/6, known as conformal coupling because the action is unchanged under conformal transformations of the metric. Any value of ξ≠0 is nonminimal coupling. A fractional version of the conformal and nonminimal coupling theory employs fractional calculus to modify the standard derivative equations and alter the Friedmann and Klein-Gordon equations. The μ fractional parameter and the age of the Universe t0 affect the evolution of cosmic species densities. This new approach to cosmology modifies the Friedmann equations and allows for late cosmic acceleration without a dark energy component. Fractional cosmology could be a significant breakthrough in solving longstanding cosmology problems, including the H0 tension.

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