Two-point tree-level string amplitudes as AdS transition amplitudes

TL;DR

This paper computes two-point string amplitudes at tree level and reveals their structural similarity to AdS boundary transition amplitudes, highlighting potential geometric aspects of open/closed string duality.

Contribution

It demonstrates that open and closed string two-point amplitudes at tree level resemble AdS transition amplitudes, suggesting a geometric interpretation of open/closed string duality.

Findings

Amplitudes are structurally analogous to AdS scalar transition amplitudes.

Different worldsheet curvatures define the 't Hooft couplings for open and closed strings.

Open/closed string duality may have a geometric interpretation.

Abstract

We compute the two-point open string and closed string amplitudes at tree level and show that, in a 't Hooft-like limit, they take a form structurally analogous to boundary-to-boundary transition amplitudes of a scalar field in Euclidean AdS space. Interestingly, while both amplitudes yield equivalent expressions, the associated 't Hooft couplings are defined by different worldsheet curvatures-geodesic for the disk and Gaussian for the sphere-suggesting a possible geometric aspect of open/closed string duality.