Cosmological Constraints on the Ψ-Field Moisten Universe Model: Resolving the Growth and Expansion History

We present a comprehensive cosmological data analysis of the newly proposed Ψ-field “MoistenUniverse” model, which introduces a classical scalar field with friction and mass to describe thebackground evolution and structure formation of the cosmos. By utilizing the latest observational data from Cosmic Chronometers (H(z)) and growth-rate measurements (fσ8), we performa joint likelihood maximization using the Nelder-Mead optimization algorithm across an unlockedparameter space. We demonstrate that the universe naturally selects the structural field constantsA ≈ 0.25 (damping) and m ≈ 3.0 (mass), precisely mirroring the theoretical foundations of themodel. The Ψ model yields a lower total chi-squared (χ2 = 22.34) compared to the standardΛCDM model (χ2 = 23.93), while successfully preserving a physically robust matter density parameter (Ωm = 0.3007) and establishing a highly stable Hubble constant (H0 = 67.07 km/s/Mpc).These results suggest that the Ψ-field framework provides a mathematically consistent and observationally superior alternative to the standard cosmological paradigm, naturally bridging the gapbetween expansion history and cosmic growth.