New supersymmetric left-right gauge model: Higgs-boson structure and neutral-current analysis

If the particle content of a supersymmetric SU(3)×SU(2)×SU(2)×U(1) gauge model is extended to include new quarks and leptons as given by the 27 representation of ${\mathrm{E}}_6$, an unconventional left-right assignment is possible, resulting in a number of desirable features, one of which is a simpler Higgs-boson structure. Also, a conserved multiplicative quantum number can be defined as a generalization of the usual R parity in most models of supersymmetry. This prevents $W_L$-$W_R$ mixing and makes possible a massless Dirac neutrino whose right-handed component is effectively inert. From neutral-current constraints based on present experimental data, lower bounds of about 180 and 210 GeV are obtained for the second W and Z bosons of this model, respectively.