Loop-corrected compactifications of the heterotic string with line bundles

We consider the E8 x E8 heterotic string theory compactified on Calabi-Yaumanifolds with bundles containing abelian factors in their structure group.Generic low energy consequences such as the generalised Green-Schwarz mechanismfor the multiple anomalous abelian gauge groups are studied. We also computethe holomorphic gauge couplings and induced Fayet-Iliopoulos terms up toone-loop order, where the latter are interpreted as stringy one-loopcorrections to the Donaldson-Uhlenbeck-Yau condition. Such models genericallyhave frozen combinations of Kaehler and dilaton moduli. We study concretebundles with structure group SU(N) x U(1)^M yielding quasi-realistic gaugegroups with chiral matter given by certain bundle cohomology classes. We alsoprovide a number of explicit tadpole free examples of bundles defined by exactsequences of sums of line bundles over complete intersection Calabi-Yau spaces.This includes one example with precisely the Standard Model gauge symmetry.Comment: 47 pages, 6 figures, LaTeX, v2: stability discussion in sect. 2.1 slightly extended, refs. added, v3: normalization of Green-Schwarz term correcte