Gauge Unification from Split Supersymmetric String Models
  We discuss the unification of gauge coupling constants in non-supersymmetric open string vacua that possess the properties of Split Supersymmetry, namely the Standard Model with Higgsinos at low energies and where the Standard model spectrum is always accompanied by right handed neutrinos. These vacua achieve partial unification of two out of three (namely SU(3)$_c$, SU(2), U(1)) running gauge couplings, possess massive gauginos and light Higgsinos at low energies and also satisfy $sin^2\theta_w (M_s) = 3/8$. These vacua are based on four dimensional orbifold $Z_3 \times Z_3$ compactifications of string IIA orientifolds with D6-branes intersecting at angles, where the (four dimensional) chiral fermions of the Standard Model appear as opens strings streching between the intersections of seven dimensional objects the so called D6-branes. 
Christos Kokorelis
hep-ph hep-th