Canonical Deformation of $N=2$ $Ad{S}_4$ SUGRA

Abstract

It is known that one can define a consistent theory of extended, $N=2$ anti-de Sitter (AdS) Supergravity (SUGRA) in $D=4$. Besides the standard gravitational part, this theory involves a single $U(1)$ gauge field and a pair of Majorana vector-spinors that can be mixed into a pair of charged spin-$3/2$ gravitini. The action for $N=2$ $Ad{S}_4$ SUGRA is invariant under $SO(1,3)\times U(1)$ gauge transformations, and under local SUSY. We present a geometric action that involves two "inhomogeneous" parts: an orthosymplectic $OSp(4|2)$ gauge-invariant action of the Yang-Mills type, and a supplementary action invariant under purely bosonic $SO(2,3)\times U(1)\sim Sp(4)\times SO(2)$ sector of $OSp(4|2)$, that needs to be added for consistency. This action reduces to $N=2$ $Ad{S}_4$ SUGRA after gauge fixing, for which we use a constrained auxiliary field in the manner of Stelle and West. Canonical deformation is performed by using the Seiberg-Witten approach to noncommutative (NC) gauge field theory with the Moyal product. The NC-deformed action is expanded in powers of the deformation parameter ${\theta }^{\mu \nu }$ up to the first order. We show that $N=2$ $Ad{S}_4$ SUGRA has non-vanishing linear NC correction in the physical gauge, originating from the additional, purely bosonic action. For comparison, simple $N=1$ Poinacaré SUGRA can be obtained in the same manner, directly from an $OSp(4|1)$ gauge-invariant action. The first non-vanishing NC correction is quadratic in ${\theta }^{\mu \nu }$ and therefore exceedingly difficult to calculate. Under Wigner-Inönü (WI) contraction, $N=2$ AdS superalgebra reduces to $N=2$ Poincaré superalgebra, and it is not clear whether this relation holds after canonical deformation. We present the linear NC correction to $N=2$ $Ad{S}_4$ SUGRA explicitly, discuss its low-energy limit, and what remains of it after WI contraction.

25 pages