Investigation of no-scale supersymmetry breaking models with a gauged U(1)B-L symmetry -: art. no. 035002

A no-scale supersymmetry (SUSY) breaking model is investigated in the minimal extension of the minimal supersymmetric standard model (MSSM) with a gauged U(1)(B-L) symmetry. We specifically consider a unification-inspired model with the gauge groups SU(3)(C)xSU(2)(L)xU(1)(Y)xU(1)(B-L)subset ofSU(5)xU(1)(5) for illustration. While the no-scale boundary condition at the grand unification scale (M(G)similar or equal to2x10(16) GeV) in the MSSM is not consistent with phenomenological constraints, we show that it is if the gaugino of the U(1)(5) multiplet is several times heavier than the gauginos of the MSSM. However, if SU(5)xU(1)(5) is further embedded in a larger simple group, e.g., SO(10), the no-scale boundary condition at M-G is inconsistent with phenomenological constraints. If we relax the no-scale boundary condition and allow nonzero soft scalar masses for the Higgs fields which spontaneously break the U(1)(5) symmetry, the resultant spectrum of SUSY particles becomes consistent with all the phenomenological constraints, even if we impose the GUT relation on the gauge coupling and the gaugino mass of the U(1)(5). In this case, the SUSY CP problem is also solved, since the condition Bmu=0 at the boundary can be imposed consistently with electroweak symmetry breaking.