A partially broken Fronsdal model for massless higher-spin particles of integer spin

By introducing arbitrary parameters in the usual Fronsdal model, we find a region in the parameters space away from the ``Fronsdal point'' where we still have an irreducible description of massless particles of arbitrary integer spin $s\ge 3$. The higher spin gauge symmetry is further constrained by a vanishing double divergence condition on the traceless gauge parameter: $\partial\cdot\partial\cdot\barΛ=0$. Remarkably, it does not introduce extra propagating gauge invariants. We demonstrate that we only have $\pm s$ helicity states as propagating modes for arbitrary integer $s\ge 3$. For the simplest $s=3$ case we present a gauge invariant proof while for $s\ge 4$ we use a light-cone gauge. The reduction in the gauge symmetry allows for more general source couplings when compared to the Fronsdal model.