A note on two-loop effects in the DMSSM

We investigate the proposed ``D-brane alternative'' to the MSSM model (DMSSM) which is a type II B string orientifold model with N=1 supersymmetry, three generations and a $SU(3)\times SU(2)_R\times SU(2)_L \times U(1)_{B-L}$ gauge group. An accurate analysis at two-loop level is performed to show that unification constraints predict a ``left-right'' symmetry breaking scale in the TeV region. The exact value of this scale is the result of the competing effects of the two loop terms against the low energy supersymmetric threshold effects. The model accommodates logarithmic unification of the gauge couplings at an intermediate scale of $10^{12}$ GeV and the necessary conditions to achieve this are addressed.