The cosmological constant in Calabi–Yau 3-fold compactifications of the Horava–Witten theory

Brane world scenarios offer a way of setting the cosmological constant to zero after supersymmetry breaking provided there is a sufficient number of adjustable integration constants/parameters. In the case of the Horava–Witten theory compactified on a Calabi–Yau three-fold, we argue that it is difficult to find enough freedom to get a zero (or small) cosmological constant after supersymmetry breaking.