This note introduces a constrained dark-energy parameterization that can be implemented directly in H (z) and BAO analyses. The model provides a reduced-degree-of-freedom alternative to CPL, with linked (w₀, wₐ) parameters arising from an underlying relaxation structure. The document includes the explicit expansion history, mapping to observables, and example comparisons to CPL fits. LaTeX source and figures are included for reproducibility.
Petersen et al. (Sun,) studied this question.