The ten-dimensional effective action of strongly coupled heterotic string theory Original Research Article

We derive the ten-dimensional effective action of the strongly coupled heterotic string as the low-energy limit of M-theory on S1/Z2. In contrast to a conventional dimensional reduction, it is necessary to integrate out non-trivial heavy modes which arise from the sources located on the orbifold fixed hyperplanes. This procedure, characteristic of theories with dynamical boundaries, is illustrated by a simple example. Using this method, we determine a complete set of R4, F2 R2, and F4 terms and the corresponding Chern-Simons and Green-Schwarz terms in ten dimensions. As required by anomaly cancellation and supersymmetry, these terms are found to exactly coincide with their weakly coupled one-loop counterparts.