Pure heterotic MSSM

As announced in October here, Braun, He, Ovrut, and Pantev have finally found an exact MSSM constructed from heterotic string theory on a specific Calabi-Yau.

• Exact MSSM

The model has the Standard Model group plus the U(1)_B-L, three generations of quarks and leptons including the right-handed neutrino, and exactly one pair of Higgs doublets which is the right matter content to obtain gauge coupling unification.

By choosing a better gauge bundle - with some novel tricks involving the ideal sheaves - they got rid of the second Higgs doublet. While they use the same Calabi-Yau space with h¹¹=h¹²=3 i.e. with 6 complex geometric moduli, they now only have 13 (instead of 19) complex bundle moduli.

The probability that this model describes reality is roughly 10⁴⁵⁰ times bigger than the probability for a generic flux vacuum, for example the vacua that Prof. Susskind uses in his anthropic interview in New Scientist. ;-)