Acceptable Inverse Power Law Potential Quintessence with n=18/7
  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 Affleck-Dine-Seiberg "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)   $\phi^2=<Q\tilde Q>$ 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 $\phi$. 
A. de la Macorra and G. German