General trilinear interaction for arbitrary even higher spin gauge fields

Using Noether’s procedure we present a complete solution for the trilinear interactions of arbitrary spins $s_1,s_2,s_3$ in a flat background, and discuss the possibility to enlarge this construction to higher order interactions in the gauge field. Some classification theorems of the cubic (self)interaction with different numbers of derivatives and depending on relations between the spins are presented. Finally the expansion of a general spin $s$ gauge transformation into powers of the field and the related closure of the gauge algebra in the general case are discussed.