  It is well-known that a (point-localized) free quantum field for massive
particles with spin $s$ acting in a Hilbert space has at best scaling dimension
$s+1$, which excludes its use in the perturbative construction of
renormalizable interacting models for higher spin ($s\geq 1$). Up to date, such
models have been constructed only in the context of gauge theory, at the cost
of introducing additional unphysical (ghost) fields and an unphysical
(indefinite metric) state space. The unphysical degrees of freedom are divided
out by requiring gauge (or BRST) invariance.
  We construct free quantum fields for higher spin particles which have the
same good UV behaviour as the scalar field (scaling dimension one), and at the
same time act on a Hilbert space without ghosts. They are localized on
semi-infinite strings extending to space-like infinity, but are linearly
related to their point-local counterparts. We argue that this is sufficient
locality for a perturbative construction of interacting models of the gauge
theory type, with a string-independent S-matrix and point-localized interacting
observable fields. The usual principle of gauge-invariance is here replaced by
the (deeper) principle of locality.
