Six Open String Disk Amplitude in Pure Spinor Superspace

TL;DR

This paper computes the six-point open string amplitude in pure spinor superspace, revealing new BRST structures and deriving extended BCJ relations from monodromy properties, advancing understanding of supersymmetric string interactions.

Contribution

It introduces a compact formulation of the six-point amplitude using pure spinor cohomology and derives extended BCJ relations from monodromy properties.

Findings

Full supersymmetric six-point amplitude expressed in compact form

Identification of BRST structures in pure spinor superspace

Extended BCJ relations verified for supersymmetric numerators

Abstract

The tree-level amplitude of six massless open strings is computed using the pure spinor formalism. The OPE poles among integrated and unintegrated vertices can be efficiently organized according to the cohomology of pure spinor superspace. The identification and use of these BRST structures and their interplay with the system of equations fulfilled by the generalized Euler integrals allow the full supersymmetric six-point amplitude to be written in compact form. Furthermore, the complete set of extended Bern-Carrasco-Johansson relations are derived from the monodromy properties of the disk world-sheet and explicitly verified for the supersymmetric numerator factors.