been misleadingly viewed as an infinite tension string. One evidence for this fact comes from
the tree level 3-point graviton amplitude, which we show to contain the usual Einstein term
plus a higher curvature contribution. After reintroducing a dimensionful parameter ℓ in the
theory, we demonstrate that the heterotic model is in fact two-fold, depending on the choice
of the supersymmetric sector, and that the spectrum also contains one massive (open string …