Off-Shell Interactions for Closed-String Tachyons

TL;DR

This paper investigates off-shell interactions of localized closed-string tachyons in C/Z_N backgrounds, deriving cubic interactions, analyzing their properties, and discussing implications for the tachyon potential and condensation.

Contribution

It provides explicit calculations of cubic interactions for nearly-massless tachyons and examines the structure of higher-order interactions in superstring backgrounds.

Findings

Cubic interactions between different-charged tachyons vanish.

Quartic contact interactions are negligible at leading order in N.

Massless exchanges fully account for the four-point scattering amplitude.

Abstract

Off-shell interactions for localized closed-string tachyons in C/Z_N superstring backgrounds are analyzed and a conjecture for the effective height of the tachyon potential is elaborated. At large N, some of the relevant tachyons are nearly massless and their interactions can be deduced from the S-matrix. The cubic interactions between these tachyons and the massless fields are computed in a closed form using orbifold CFT techniques. The cubic interaction between nearly-massless tachyons with different charges is shown to vanish and thus condensation of one tachyon does not source the others. It is shown that to leading order in N, the quartic contact interaction vanishes and the massless exchanges completely account for the four point scattering amplitude. This indicates that it is necessary to go beyond quartic interactions or to include other fields to test the conjecture for the height of the tachyon potential.