Heterotic Standard Model Moduli
  In previous papers, we introduced a heterotic standard model and discussed its basic properties. The Calabi-Yau threefold has, generically, three Kahler and three complex structure moduli. The observable sector of this vacuum has the spectrum of the MSSM with one additional pair of Higgs-Higgs conjugate fields. The hidden sector has no charged matter in the strongly coupled string and only minimal matter for weak coupling. Additionally, the spectrum of both sectors will contain vector bundle moduli. The exact number of such moduli was conjectured to be small, but was not explicitly computed. In this paper, we rectify this and present a formalism for computing the number of vector bundle moduli. Using this formalism, the number of moduli in both the observable and strongly coupled hidden sectors is explicitly calculated. 
Volker Braun, Yang-Hui He, Burt A. Ovrut, and Tony Pantev