Transit f(Q,T) Gravity Model: Observational Constraints with Specific Hubble Parameter

Abstract

The present analysis deals with the study of the f(Q,T) theory of gravity, which was recently considered by many cosmologists. In this theory of gravity, the action is taken as an arbitrary function f(Q,T), where Q is non-metricity and T is the trace of the energy–momentum tensor for matter fluid. In this study, we took two different forms of the function f(Q,T) as f(Q,T)=a1Q+a2T and f(Q,T)=a3Q2+a4T, and discussed the physical properties of the models. Also, we obtained the various cosmological parameters for the Friedmann–Lemaître–Robertson–Walker (FLRW) universe by defining the transit form of a scale factor that yielded the Hubble parameter in redshift form, as H(z)=H0(λ+1)λ+(1+z)δ. We obtained the best-fit values of model parameters using the least squares method for observational constraints on available datasets, like Hubble H(z), Supernova SNe-Ia, etc., by applying the root mean squared error formula (RMSE). For the obtained approximate best-fit values of model parameters, we observed that the deceleration parameter q(z) shows a signature-flipping (transition) point within the range of 0.623≤z0≤1.668. Thus, it shows the decelerated expansion transiting into the accelerated universe expansion with ω→−1 as z→−1 in the extreme future.