Modified f(Q,C) gravity dark energy models with observational constraints

We investigate an isotropic and homogeneous flat dark energy model in $f(Q,C)$ gravity theory that is linear in non-metricity Q and quadratic in boundary term C as $f(Q,C)=Q+\alpha C^2$, where $\alpha$ is a model parameter. We have solved the field equations in flat Friedmann–Lemaitre–Robertson–Walker (FLRW) spacetime geometry and considered a relation in the form of Hubble function in total energy density parameters ${\mathrm{\Omega }}_{m0}$, ${\mathrm{\Omega }}_{0(Q,C)}$, and Hubble constant $H_0$. We have compared our results with two observational datasets $H(z)$ and Pantheon SNe Ia datasets by using MCMC analysis and have obtained the best fit present values of parameters. We have used these best fit values throughout in result analysis and discussion. We have found the equation of state (EoS) parameter as $-1\le \omega \le 0.2$ over $-1\le z\le 3$. We have also investigated the Om diagnostic function and present age of the universe for these two datasets.