A NEW STANDARD-LIKE MODEL IN THE 4-DIMENSIONAL FREE FERMIONIC STRING FORMULATION

I present a new three generation superstring standard-like model in the free fermionic formulation with the following properties. The complete massless spectrum is derived and shown to be anomaly free apart from a single anomalous U(1). The Dine-Seiberg-Witten mechanism is applied to cancel the anomaly, leaving a supersymmetric vacuum. I show that the resulting observable gauge symmetry is SU(3) x SU(2) x U(1)n where n = 1 or 2. All trilinear superpotential couplings have been calculated. I show that of the standard model quarks and leptons, only + 2/3 charged quarks obtain a non vanishing trilevel coupling, which suggests a possible explanation for the heaviness of the top quark relative to the lighter quarks and leptons. The additional, generation independent, U(1) symmetry may remain unbroken down to low energies and prevents fast proton decay.