Tweaking gravity's geometry to explain dark energy's behavior

This study reconstructs a Tsallis Holographic Dark Energy model inside f(Q,C) gravity — a theory where spacetime curvature is replaced by non-metricity and its boundary term. The reconstructed model is fitted against combined Cosmic Chronometers, Pantheon+, and DESI DR2 data via MCMC, yielding parameters consistent with the observed age of the Universe. Statefinder diagnostics show the model's trajectory passes through the ΛCDM fixed point, and all four standard energy conditions are satisfied. The results are strongly sensitive to initial conditions and the chosen parameter space, which limits predictive sharpness.