ASPECTS OF NON-RENORMALIZABLE TERMS IN A SUPERSTRING DERIVED STANDARD-LIKE MODEL

I investigate the role of non-renormalizable terms, up to order N = 8, in a superstring derived standard-like model. I argue that non-renormalizable terms restrict the gauge symmetry, at the Planck scale, to be SU(3) X SU(2) X U(1)B-L X U(1)T3R rather than SU(3) X Su(2) X U(1)Y. I show that breaking the gauge symmetry directly to the Standard Model leads to breaking of supersymmetry at the Planck scale, or to dimension four, baryon and lepton violating, operators. I show that if the gauge symmetry is broken directly to the Standard Model the cubic-level solution to the F and D flatness constraints is violated by higher-order terms, while if U(1)Z, remains unbroken at the Planck scale, the cubic-level solution is valid to all orders of non-renormalizable terms. I discuss the Higgs and fermion mass spectrum. I demonstrate that realistic, hierarchical, fermion mass spectrum can be generated in this model.