Observational constraints on f(T) gravity from varying fundamental constants

We use observations related to the variation of fundamental constants, in order to impose constraints on the viable and most used f (T) gravity models. In particular, for the fine-structure constant we use direct measurements obtained by different spectrographic methods, while for the effective Newton constant we use a model-dependent reconstruction, using direct observational Hubble parameter data, in order to investigate its temporal evolution. We consider two f (T) models and we quantify their deviation from CDM cosmology through a sole parameter. Our analysis reveals that this parameter can be slightly different from its CDM value, however, the best-fit value is very close to the CDM one. Hence, f (T) gravity is consistent with observations, nevertheless, as every modified gravity, it may exhibit only small deviations from CDM cosmology, a feature that must be taken into account in any f (T) model-building.