Stringy surprises

Abstract

There are many conceivable possibilities of embedding the MSSM in string theory. These proceedings describe an approach which is based on grand unification in higher dimensions. This allows one to obtain global string-derived models with the exact MSSM spectrum and built-in gauge coupling unification. It turns out that these models exhibit various appealing features such as (i) see-saw suppressed neutrino masses, (ii) an order one top Yukawa coupling and potentially realistic flavor structures, (iii) non-Abelian discrete flavor symmetries relaxing the supersymmetric flavor problem, (iv) a hidden sector whose scale of strong dynamics is consistent with TeV-scale soft masses, and (v) a solution to the mu-problem. The crucial and unexpected property of these features is that they are not put in by hand nor explicitly searched for but happen to occur automatically, and might thus be viewed as "stringy surprises".