## Friday, December 16, 2005 ... //

### 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.

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. ;-)

#### snail feedback (1) :

hmm, assuming that reality is just the representation of the particles and such. how about the interactions and everything else?

a high school physics book describes reality better.

there's no such thing as the probablity a theory describes reality. how about the probablity of that you are actually yourself? it either describes or not, yes or no.

a theory of reality is not a photograph of reality either. the standard model is more appealing at this level.

if there's nothing at the level of insights out of this theory, we might just treat it as amusing entertainment, which many people are I guess.

don't throw too much tomatos and eggs, please.

merry christmas