Relations between positivity, localization and degrees of freedom: The Weinberg-Witten theorem and the van Dam-Veltman-Zakharov discontinuity

This approach allows to overcome the Weinberg-Witten impediment against the existence of massless |h|≥2 energy-momentum tensors, and to qualitatively and quantitatively resolve the van Dam-Veltman-Zakharov discontinuity concerning, e.g., very light gravitons, in the limit m→0.