Cosmological dynamics and observational constraints on a viable f(Q) nonmetric gravity model

Inspired by an exponential Formula: see text gravity model studied in the literature, in this work we introduce a new and viable Formula: see text gravity model, which can be represented as a perturbation of Formula: see textCDM. Typically, within the realm of Formula: see text gravity, the customary approach to investigate cosmological evolution involves employing a parametrization of the Hubble expansion rate in terms of the redshift, Formula: see text, among other strategies. In this work, we have implemented a different strategy, deriving an analytical approximation for Formula: see text, from which we deduce approximated analytical expressions for the parameters Formula: see text, Formula: see text and Formula: see text, as well as the deceleration parameter q. In order to verify the viability of this approximate analytical solution, we examined the behavior of these parameters in the late-time regime, in terms of the free parameter of the model, b. We find that for Formula: see text, Formula: see text shows a quintessence-like behavior, while for Formula: see text, it shows a phantom-like behavior. However, regardless of the sign of b, Formula: see text exhibits a quintessence-like behavior. Furthermore, it has been deduced that as the magnitude of the parameter b increases, the present model deviates progressively from Formula: see textCDM. We have also performed a Markov Chain Monte Carlo statistical analysis to test the model predictions with the Hubble parameter, the Pantheon supernova (SN) observational data and the combination of those samples, obtaining constraints on the parameters of the model and the current values of the Hubble parameter and the matter density. Our findings indicate that this Formula: see text gravity model is indeed a viable candidate for describing the late-time evolution of the Universe at the background level.