PHYSICS Journal: Theoretical and Experimental Studies
Research Article Volume: 1 & Issue: 1
Abstract
While various parametrizations of the Hubble parameter have been proposed to model the universe’s expansion, their viability within higher-dimensional modified gravity remains largely untested. This study rigorously investigates the cosmological dynamics of five distinct Hubble models (hyperbolic tangent, logarithmic, power-law, exponential decay, and emergent) within a Kaluza-Klein f(R,T)gravity framework. Crucially, beyond standard kinematic evolution, we subject these models to a comprehensive stability analysis using the squared speed of sound and energy condition constraints. We demonstrate that while most parametrizations can successfully mimic late-time cosmic acceleration, only the Logamediate Model (Model III) maintains perturbative stability throughout the cosmic history. This work establishes a critical selection criterion for modified gravity reconstructions, filtering out observationally consistent but theoretically unstable dark energy candidates.