MCMC constraints on dark sector dynamics in f(R, Lm, T) modified gravity
Myrzakulov Y. Alfedeel A.H.A. Koussour M. Muminov S. Ali S.O. Rayimbaev J.
2025World Scientific
International Journal of Geometric Methods in Modern Physics
2025
As new gravitational theories emerge, their ability to explain the dark sector of the universe becomes increasingly important. In this study, we investigate the f(R, Lm, T) gravity model, which extends the f(R, T) and f(R, Lm) frameworks by unifying the Ricci scalar R, the matter Lagrangian Lm, and the trace of the energy-momentum tensor T within a single gravitational Lagrangian. Using the functional form f(R, Lm, T) = R+ αLm + βT, where α and β are constants, we solve the field equations for the Hubble parameter H(z) with a parametric equation of state ωeff as a function of redshift z. The results of our MCMC analysis, based on Hubble and SNe Ia datasets, yield tightly constrained model parameters (α ≈ −5, β ≈ 4.7 − 4.9, m ≈ 0.5, and n ≈ 2.45), with the joint dataset reducing uncertainties. The model successfully captures the evolution of the Hubble parameter, deceleration parameter, energy density, and the Om(z) diagnostic, showing a transition from deceleration to acceleration and an eventual de Sitterlike expansion at z = −1. The ωeff (z) consistently describes the universe’s expansion across different epochs, reinforcing the validity of the f(R, Lm, T) gravity model and its ability to replicate key cosmological features.
deceleration parameter , equation of state , f(R , Lm , observational constraints , T) gravity
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Department of General & Theoretical Physics L.N. Gumilyov Eurasian National University, Astana, 010008, Kazakhstan
Department of Mathematics and Statistics Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, 13318, Saudi Arabia
Department of Physics University of Hassan II, Casablanca, Morocco
Mamun University, Bolkhovuz, Khiva, 220900, Uzbekistan
Urgench State University, Kh. Alimjan, Urgench, 221100, Uzbekistan
University of Tashkent for Applied Sciences, Street Gavhar 1, Tashkent, 100149, Uzbekistan
Department of General & Theoretical Physics L.N. Gumilyov Eurasian National University
Department of Mathematics and Statistics Imam Mohammad Ibn Saud Islamic University (IMSIU)
Department of Physics University of Hassan II
Mamun University
Urgench State University
University of Tashkent for Applied Sciences
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