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

March 13, 2017

The problem of accounting for the degrees of freedom in passing from massive
spin to massless helicity degrees of freedom and its inverse, the "fattening"
of massless tensor fields to their massive $s = |h|$ counterparts, are solved
using "string-localized fields". This approach allows to overcome the
Weinberg-Witten impediment against the existence of massless $|h|\geq 2$
energy-momentum tensors, and to replace the van Dam-Veltman-Zakharov
discontinuity concerning, e.g., very light gravitons, by a continuous limit $m
\to 0$.

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