Chiral Closed strings: Four massless states scattering amplitude

TL;DR

This paper calculates four-point scattering amplitudes for massless states in chiral closed strings, revealing their relation to field theory amplitudes and highlighting differences between bosonic and superstring cases.

Contribution

It provides explicit computations of scattering amplitudes for chiral closed strings using KLT factorization, clarifying their spectrum and pole structure.

Findings

Bosonic chiral string amplitude matches a specific field theory amplitude.

Superstring amplitude contains only massless gravitational poles.

Extension to heterotic superstrings is briefly discussed.

Abstract

We compute the scattering amplitudes of four massless states for chiral (closed) bosonic and type II superstrings using the Kawai-Lewellen-Tye ($KLT$) factorization method. The amplitude in the chiral bosonic case is identical to a field theory amplitude corresponding to the spin-$2$ tachyon, massless gravitational sector and massive spin-2 tardyon states of the spectrum. Chiral type II superstrings amplitude only possess poles associated with the massless gravitational sector. We briefly discuss the extension of the calculation to heterotic superstrings.