Exact Cosmological Models in Modified f (R, Lm) Gravity with Observational Constraints

This study is an investigation of exact cosmological models in modified f(R, L-m) gravity with observational constraints, where R is the Ricci scalar, and L-m is the matter Lagrangian for a perfect fluid. We have obtained the field equations using a flat FLRW metric with matter Lagrangian L-m = -rho and f(R, L-m) = R/2+ alpha L-m(n) - ss, where alpha, ss, n are positive parameters. We have solved the field equations for the scale factor a(t) with the equation of state (EoS) rho =omega rho, where rho is the isotropic pressure and. is the energy density. We have obtained the scale factor a(t) = k(0)[sinh(k(1)t + k(2))][2(n+omega- n omega]/[3n(1+omega)], where k1 = root 3 beta/2 n(1+omega)/n+omega-n omega, and k(0), k(2) are integration constants. Using this scale factor, we have analyzed various cosmological parameters {H-0, q(0), j(0), s(0), t(0)} with observational constraints by applying the chi(2) test with four observational datasets H(z), Union 2.1, JLA and Bined datasets. Also, we have analyzed the Om diagnostic parameter.