Higgs doublets, split multiplets and heterotic SU(3)C×SU(2)L×U(1)Y spectra

A methodology for computing the massless spectrum of heterotic vacua with Wilson lines is presented. This is applied to a specific class of vacua with holomorphic SU(5)-bundles over torus-fibered Calabi-Yau threefolds with fundamental group Z2. These vacua lead to low-energy theories with the standard model gauge group SU(3)C×SU(2)L×U(1)Y and three families of quark/leptons. The massless spectrum is computed, including the multiplicity of Higgs doublets.