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The system of higher spins 0, 2, 4, … (every spin enters just once) is studied in the framework of the light-cone formalism at the level of the fourth-order approximation. It is shown that there exist definite values of the cubic interactions constants for which the Poincaré algebra remains closed on the mass shell. These values are expressed through the value of the one universal constant.
R.R. Metsaev (Sun,) studied this question.