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Radial Reduction and Cubic Interaction for Higher Spins in (A)dS space

We present a new version of the radial reduction formalism to obtain a cubic interaction of higher spin gauge fields in $AdS_{d+1}$ space from the corresponding cubic interaction in a flat $d+2$ dimensional background. We modify the radial reduction procedure proposed previously by T. Biswas and W. Siegel in 2002 and applied to the free higher spin Lagrangian by K. Hallowell and A. Waldron in 2005. This modified radial reduction scheme is applied to interacting massless higher spin fields in Fronsdal's formulation, and all results are expressed in a direct $AdS_{d+1}$ invariant way with $AdS$ covariant derivatives. We present a consistent algorithm and define new procedure to obtain all corrections proportional to powers of the cosmological constant, and apply these to the main term of the cubic self-interaction.