Speaker
Description
By incorporating torsional gravity into the effective field theory (EFT)perspective, the model offers a unified and By Incorporating torsional gravity into the EFT perspective offers a unified and consistent framework to fit observations solving the two tensions. Both the H0 and Ï8 tensions can simultaneously be alleviated within torsional gravity by the EFT approach. Further, we investigate the scalar perturbations and the possible strong coupling issues of f(T ) around a cosmological background. We apply the EFT framework by considering both linear and second-order perturbations for f(T ) theory. We find that no new scalar mode is present in both linear and second-order perturbations in f(T ) gravity, which suggests a strong coupling problem. However, based on the ratio of cubic to quadratic Lagrangians, we provide a simple estimation of the strong coupling scale, a result which shows that the strong coupling problem can be avoided at least for some modes. In conclusion, perturbation behaviors that at first appear problematic may not inevitably lead to a strong coupling problem, as long as the relevant scale is comparable with the cutoff scale M of the applicability of the theory.
