Non-perturbative vacua in heterotic M-theory

We present a class of N = 1 supersymmetric 'standard' models of particle physics, derived directly from heterotic M-theory, that contain three families of chiral quarks and leptons coupled to the gauge group SU(3)(C) x SU(2)(L) x U(1)(Y). These models are a fundamental form of 'brane world' theories, with an observable and hidden sector each confined, after compactification on a Calabi-Yau 3-fold, to a BPS 3-brane separated by a higher-dimensional bulk space with size of the order of the intermediate scale. The requirement of three families, coupled to the fundamental conditions of anomaly freedom and supersymmetry, constrains these models to contain additional 5-branes located in the hulk space and wrapped around holomorphic curves in the Calabi-Yau 3-fold.