Late-time cosmology in f(Q,Lm) gravity: Analytical solutions and observational fits

Abstract

In this study, we examined the late-time cosmic expansion of the universe within the framework of f(Q,Lm) gravity, where Q denotes the non-metricity and Lm represents the matter Lagrangian. We analyzed a linear f(Q,Lm) model of the form f(Q,Lm)=−αQ+2Lm+β. Using MCMC methods, we constrained the model parameters H0, α, and β with various datasets, including H(z), Pantheon+SH0ES, and BAO data. For the H(z) dataset, we found H0=67.90±0.66, α=0.1072−0.0069+0.0054, and β=−1988.2±1.0. For the Pantheon+SH0ES dataset, H0=70.05±0.68, α=0.0916−0.0033+0.0028, and β=−1988.3±1.0. For the BAO dataset, H0=68.1±1.0, α=0.1029−0.0052+0.0041, and β=−1988.24±0.99. Moreover, the energy density remains positive and approaches zero in the distant future, and the deceleration parameter indicates a transition from deceleration to acceleration, with transition redshifts of zt=0.60, zt=0.78, and zt=0.66 for the respective datasets. These findings align with previous observational studies and contribute to our understanding of the universe's expansion dynamics.