285 research outputs found

    How universe evolves with cosmological and gravitational constants

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    With a basic varying space-time cutoff β„“~\tilde\ell, we study a regularized and quantized Einstein-Cartan gravitational field theory and its domains of ultraviolet-unstable fixed point gir≳0g_{\rm ir}\gtrsim 0 and ultraviolet-stable fixed point guvβ‰ˆ4/3g_{\rm uv}\approx 4/3 of the gravitational gauge coupling g=(4/3)G/GNewtong=(4/3)G/G_{\rm Newton}. Because the fundamental operators of quantum gravitational field theory are dimension-2 area operators, the cosmological constant is inversely proportional to the squared correlation length Ξ›βˆΞΎβˆ’2\Lambda\propto \xi^{-2}. The correlation length ΞΎ\xi characterizes an infrared size of a causally correlate patch of the universe. The cosmological constant Ξ›\Lambda and the gravitational constant GG are related by a generalized Bianchi identity. As the basic space-time cutoff β„“~\tilde\ell decreases and approaches to the Planck length β„“pl\ell_{\rm pl}, the universe undergoes inflation in the domain of the ultraviolet-unstable fixed point girg_{\rm ir}, then evolves to the low-redshift universe in the domain of ultraviolet-stable fixed point guvg_{\rm uv}. We give the quantitative description of the low-redshift universe in the scaling-invariant domain of the ultraviolet-stable fixed point guvg_{\rm uv}, and its deviation from the Ξ›\LambdaCDM can be examined by low-redshift (z≲1)(z\lesssim 1) cosmological observations, such as supernova Type Ia.Comment: typo corrections, the final version to appear in Nucl. Phys. B (2015). 24 pages and 6 figure
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