Massive spin-two field
= Massive spin-two field
{title2=$(\Box-m^2)h_{mn}=0,\quad\partial^mh_{mn}=0,\quad h^m{}_m=0$}
A free massive spin-two field is a <symmetric tensor> obeying a massive <Klein-Gordon equation>, vanishing divergence, and vanishing <trace>. Its rest-frame polarizations form the <symmetric traceless square> of the $SO(D-1)$ vector, with $(D-2)(D+1)/2$ degrees of freedom.