A Note on String Excitations and the Higuchi Bound

Understand

In this brief note we consider the interaction between high spin excitations in string theory along the Regge trajectory and the Higuchi bound in de Sitter space.

• There is always a point along the Regge trajectory where the Higuchi bound is violated.
• However, this point precisely coincides with a string whose length is of order the de Sitter Hubble scale.
• String theory therefore manifests no immediate inconsistency as long as the string scale $M_s$ is above the Hubble scale $H$.