Speaker
Description
Understanding the origin of cosmic acceleration and the persistent H_0 and S_8 tensions remains a major challenge in cosmology. In this talk, I explore alternatives to the standard LambdaCDM model based on both modified gravity and dynamical dark energy. Within the teleparallel framework, I discuss f(Q) and f(T) theories, showing how non-metricity and torsion can lead to novel cosmological dynamics, including the resolution of cosmological singularities and partial alleviation of current observational tensions. I also present several dark energy scenarios, including sign-switching dark energy, axion-inspired quintessence, and 3-form fields, and assess their observational viability using recent cosmological datasets. While none of the models fully resolves all existing discrepancies, several provide a better fit to the data and significantly reduce the Hubble tension. These results highlight the potential of both modified gravity and dynamical dark energy as promising frameworks for understanding the late-time evolution of the Universe.