On possible composite structure of scalar fields in expanding universe

Abstract

Scalar fields in curved backgrounds are assumed to be composite objects. As an example realizing such a possibility we consider a model of the massless tensor field l_{mu nu }(x) in a 4-dim. background g_{mu nu }(x) with spontaneously broken Weyl and scale symmetries. It is shown that the potential of l_{mu nu }, represented by a scalar quartic polynomial, has the degenerate extremal described by the composite Nambu–Goldstone scalar boson phi (x):=g^{mu nu }l_{mu nu }. Removal of the degeneracy shows that phi acquires a non-zero vev langle phi rangle _{0}=mu which, together with the free parameters of the potential, defines the cosmological constant. The latter is zero for a certain choice of the parameters.