A note on two-loop effects in the DMSSM Original Research Article

We investigate the proposed “D-brane alternative” to the MSSM model (DMSSM) which is a type-IIB string orientifold model with N=1 supersymmetry, three generations and a SU(3)×SU(2)R×SU(2)L×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 1012 GeV and the necessary conditions to achieve this are addressed.