https://doi.org/10.1140/epjc/s10052-014-2729-2
Regular Article - Theoretical Physics
On the effect of the degeneracy among dark energy parameters
1
MOE Key Laboratory of Fundamental Quantities Measurement, School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
2
Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
* e-mail: yggong@mail.hust.edu.cn
Received:
24
October
2013
Accepted:
31
December
2013
Published online:
30
January
2014
The dynamics of scalar fields as dark energy is well approximated by some general relations between the equation of state parameter 
and the fractional energy density 
. Based on the approximation, for slowly rolling scalar fields, we derived the analytical expressions of which reduce to the popular Chevallier–Polarski–Linder parametrization with an explicit degeneracy relation between 
and 
. The models approximate the dynamics of scalar fields well and help eliminate the degeneracies among , , and 
. With the explicit degeneracy relations, we test their effects on the constraints of the cosmological parameters. We find that: (1) The analytical relations between and for the two models are consistent with observational data. (2) The degeneracies have little effect on . (3) The 
error of was reduced about 30 % with the degeneracy relations.
© The Author(s), 2014
