The Paths of Unification In The GUST With The G x G Gauge Groups of E(8)   x E(8)
  In the framework of the four dimensional heterotic superstring with free fermions we discuss the rank eight and/or sixteen Grand Unified String Theories (GUST) which contain the SU(3)_H - gauge family symmetry. We explicitly investigate the paths of the unification in the GUST with gauge symmetry G x G = [SU(5) x U(1) x (SU(3) x U(1))_H]^2. We show that the GUSTs with the G x G gauge group allow to make the scale of unification to be consistent with the string scale M_SU = g_{string} * 5 * 10^17 GeV. 
A. Maslikov (2), I. Naumov (2), G. Volkov (1,2) ((1) INFN Sezione di   Padova and Dipartimento di Fisica Universit\`a di Pad...