Higgs as (pseudo-) Nambu-Goldstone particles

Higgs scalars may be (pseudo-) Nambu-Goldstone particles related to a spontaneous breakdown of a global symmetry which contains grand unified gauge group as a subgroup. This hypothesis gives severe constraint on possible form of Higgs mass terms in a framework of supersymmetric grand unified theories coupled to N = 1 supergravity. Remarkably, their tree level mass terms, both supersymmetric and soft-breaking, are definitely given by gravitino mass m3/2 and do not depend on a detailed structure of a superpotential of GUT sector. These mass terms are best desirable for the relatively light top quark(mt < approx 50 GeV) suggested at CERN to be active in the radiative SU(2) X U(1) breaking scenario. (author)