BRST properties of spin fields

TL;DR

This paper investigates the BRST properties of spin fields in four-dimensional superstring theory, providing explicit operator product expansions, BRST picture changing, and analyzing gauge symmetry and modular invariance.

Contribution

It introduces a covariant notation for spin state decomposition and computes the most general BRST picture changing for spin fields in four dimensions.

Findings

Explicit operator product expansions consistent with BRST invariance

Covariant spin decomposition notation developed

Analysis of gauge symmetry and modular invariance in 4D models

Abstract

For the closed superstring, spin fields and bi-spinor states are defined directly in four spacetime dimensions. Explicit operator product expansions are given, including those for the internal superconformal field theory, which are consistent with locality and BRST invariance for the string vertices. The most general BRST picture changing for these fields is computed. A covariant notation for the spin decomposition of these states is developed in which non-vanishing polarizations are selected automatically. The kinematics of the three-gluon dual model amplitude in both the Neveu-Schwarz and Ramond sectors in the Lorentz gauges is calculated and contrasted. Modular invariance and enhanced gauge symmetry of four-dimensional models incorporating these states is described.