University of Khartoum

A Coasting Universe with Vacuum Energy

A Coasting Universe with Vacuum Energy

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Title: A Coasting Universe with Vacuum Energy
Author: Arbab, Arbab I.
Abstract: We have studied a cosmological model with a cosmological term of the form ¤ = 3® ˙R2 R2 + ¯ ¨R R + 3° R2 ; ®; ¯ ; ° are constants. The scale factor (R) is found to vary linearly with time for both radiation and matter dominated epochs. The cosmological constant is found to decrease as t¡2 and the rate of particle creation is smaller than the Steady State value. The model gives ­¤ = 1 3 and ­m = 2 3 in the present era, ­¤ = ­m = 1 2 in the radiation era. The present age of the universe (tp ) is found to be tp = H¡1 p , where Hp is the Hubble constant. The model is free from the main problems of the Standard Model. Since the scale factor R / t during the entire evolution of the universe the ratio of the cosmological constant at the Planck and present time is ¤Pl ¤p = 10120 . This decay law justifies why, today, the cosmological constant is exceedingly small.
URI: http://khartoumspace.uofk.edu/handle/123456789/17660
Date: 2015-12-15


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