Acceptable IPL Quintessence with n=18/7
Abstract
We present a particle physics quintessence model which agrees well with existing cosmological data, including the position of the acoustic peaks. This model has an inverse power law potential (IPL) with n=18/7\sim 2.57 and it gives weff=-0.75, an acoustic scale l_A=307 and a density contrast s8=0.95. Models with n>1 have been said to be disfavored by the analysis of the acoustic peaks. However, the results are not correct. The main reason is that the tracker approximation has been used in deriving the IPL constrains and for $n<5$ the scalar field has not reached its tracker value by present day. The model can be derived from particle physics, using ADS superpotential, for a non-abelian gauge group with N_c=8, N_f=1. The advantage of having N_f=1 is that there is only one degree of freedom below the condensation scale given by the condensate (quintessence) phi= field. The condensation scale is at 1 GeV a very interesting scale since it connects the quintessence "Q" with the standard model "SM" scale. The similarity in energy scales between Q and SM scale gives an "explanation" to the coincidence problem. The fact that only recently the universe is accelerating is a natural consequence of the Q scale and the evolution of phi.
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