Graviphoton

The vector field of the N=2 supergravity multiplet [1]. It may serve as the gauge field coupling to the superalgebra's central charge [2], and, in fact, this proves to be necessary for local supersymmetry , e.g., when massive supermultiplets are coupled to N=2 supergravity [3]. The effective coupling is , where m is the mass of the matter excitations and M _Pl the Planck mass, and hence, naively, the classical force equals the gravitational attraction in strength [3]. This is expected from its origin as a graviton component in higher dimensions. With symmetry breaking, this vector field becomes massive [4], and hence its range is shortened. By extension, all vector fields in supergravity multiplets behave similarly, leading to a large class of modifications to the classical gravitation force [5].